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Improving the Safety and Quality of Fresh Fruits and Vegetables: A Training Manual for Trainers

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Table of Contents

IntroductionTable of Contents ......................................................................................iIntroduction .................................................................................................v

About This Manual .....................................................................................v

Acronyms......................................................................................................ix

Principles

SECTION I. THE IMPORTANCE OF TRAINING FOR IMPROVING THE SAFETY ANDQUALITY OF FRESH FRUITS AND VEGETABLESModule 1. Safety Hazards In Fresh Produce –

Biological, Chemical and Physical........................................I-2Module 2. Fresh Produce Safety and Consumer Health ...................I-13Module 3. Impact of Produce Safety on Trade ......................................I-18References..................................................................................................I-22

SECTION II. GOOD AGRICULTURAL PRACTICES

Module 1. Soil and Water .........................................................................II-3Module 2. Organic and Inorganic Fertilizers .........................................II-16

Module 3. Animal Exclusion and Pest Control .....................................II-27Module 4. Worker Health and Safety ......................................................II-39Module 5. Harvesting and Cooling .........................................................II-50

References .................................................................................................II-63

SECTION III. GOOD MANUFACTURING PRACTICES FOR HANDLING, PACKING, STORAGE AND TRANSPORTATION OF FRESH PRODUCE

Module 1. Produce Cleaning and Treatment .......................................III-2Module 2. Packing, Storage and Transportation .................................III-15Module 3. Equipment Cleaning and Sanitation ...................................III-25References .................................................................................................III-33

IMPROVING THE SAFETY AND QUALITYOF FRESH FRUIT AND VEGETABLES:

A TRAINING MANUAL FOR TRAINERS


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SECTION IV. FOOD LAWS AND REGULATIONSModule 1. The U.S. Food Safety System................................................IV-2Module 2. Investigating Foodborne Disease Outbreaks....................IV-9

Module 3. International Food Laws and Regulations..........................IV-16References .................................................................................................VI-23

SECTION V. FOOD SAFETY AND QUALITY ASSURANCE ISSUESModule 1. Safety and Quality Assurance ...............................................V-2Module 2. Quality Attributes, Grades and Standards ..........................V-10Module 3. Quality Attributes and Spoilage ............................................V-18References .................................................................................................V-25

SECTION VI. DEVELOPING AN EFFECTIVE TRAINING COURSE Module 1. Planning for Effective Training: Identifying Needs

and Setting Objectives ............................................................VI-2 Module 2. Preparing and Organizing the Training Content ...............VI-9Module 3. Conducting and Evaluating the Course ..............................VI-18References .................................................................................................VI-25

Practical

Introduction ........................................................................................................................P-3Experiments/Demonstrations

• Water as a Contamination Agent ............................................................P-4• Product Integrity and Produce Contamination .....................................P-6

• Handwashing ............................................................................................P-8• Chlorine Concentration and Water Quality Management ..................P-10• Fruit Spoilage .............................................................................................P-13• Experiments Using Artificial “Germs”:

Handwashing .................................................................................P-15How Germs are Spread - I............................................................P-16How Germs are Spread – II .........................................................P-16Germs and Produce ......................................................................P-16

• Fresh Produce Quality ..............................................................................P-18Discussion Questions .....................................................................................................P-19Problem Solving Exercises

Traceback Investigation.............................................................................P-20Planning for an Effective Training Course on GAPs: 3 Scenarios ….

............................................................................................................P-22Field Site Visit Guide ........................................................................................................P-24


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Introduction

The health benefits associated with regular consumption of fresh fruits and vegetables

have been clearly demonstrated and encouraged by national and international nutritionand health authorities. However, increased consumption of these products has beenassociated with a increased proportion of reported outbreaks of foodborne illness thatcan be traced to fresh produce. Recent outbreaks of foodborne illness, such as thosein the U.S. involving E. coli O157:H7 in lettuce and Salmonella in cantaloupe, and thefact that most fresh produce is not processed, a step which generally reduces or eliminates pathogens, have raised concerns regarding the potential safety of freshfruits and vegetables.

Background

In 1998, the U.S. Food and Drug Administration (FDA) and U.S. Department of Agriculture (USDA) issued the document "Guidance for Industry -- Guide to MinimizeMicrobial Food Safety Hazards for Fresh Fruits and Vegetables." This document,referred to as the Guide, addressed microbial food safety hazards and good agriculturaland manufacturing practices (GAPs and GMPs) common to the growing, harvesting,cleaning/washing, sorting, packing, and transporting of most fruits and vegetables soldto consumers in an unprocessed or minimally processed (raw) form. This voluntary,science-based guidance was designed to be used by both domestic and foreign freshfruit and vegetable producers to help ensure the safety of their produce. The voluntaryguidance is consistent with U.S. trade rights and obligations and does not imposeunnecessary or unequal restrictions or barriers on either domestic or foreign

producers.

That same year, the Food and Agriculture Organization of the United Nations (FAO) inconjunction with the Institute of Food Science and Engineering, University of Arkansas(IFSE/UA) initiated plans to develop a regional training course for Mexico and Central

America on quality assurance and safety of fresh produce. The Government of Guatemala hosted a planning Workshop for this training in Guatemala City inDecember 1998. The 10-day FAO Regional Training Course took place in June 1999 atthe School of Tropical and Humid Agriculture (EARTH) and was hosted by theGovernment of Costa Rica. The participants at both the planning workshop and thetraining course indicated a critical need for more training opportunities and greater

availability of training materials on safety and quality of fresh fruits and vegetables.

About This Manual

The objective of this manual is to provide uniform, broad-based scientific and practicalinformation on the safe production, handling, storage, and transport of fresh produce.This manual will:


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As training needs vary by country, the time frame for training and the extent of trainingwill also vary. It is anticipated that the length of time to present the Principles andPractical information will be 5-7 days with the inclusion of a field site visit. The

backgrounds and needs of the course participants will determine how much timeshould be spent on each of the training modules. Logistics, budget, and schedulesmay dictate shorter or split sessions and the number of Practical activities that areincluded. Since interactive sessions with discussions, lab demonstrations, field visits,and case studies are an important part of the training process, the number of participants needs to be limited to a manageable level for trainers and facilities.

Included throughout the Principles section are suggestions for information that may behighlighted as visuals. These are intended as suggestions for visuals, not as actualvisual masters. Depending on the amount of material to be presented, the type of visualaids to be used, and the size of the training group, the trainer may choose to present

each as a single visual or as multiple slides, overheads, charts, or posters.

The Practical section of the manual includes activities to involve participants in thetraining. Use of these activities will enhance training of trainers by complementinglecture material and by providing the participants with ideas for activities to enrich their own training efforts. Suggestions for activities related to training topics are included atthe beginning of each of the training modules. Trainers of trainers are encouraged touse as many of these as time and resources will allow.

In Volume II, the commodity specific case studies allow participants to apply therecommended GAPs and GMPs in examples relevant to Latin America and the

Caribbean. These case studies have been developed with direct input from producersin the region to ensure that topics and presentation are appropriate. They are intendedto build understanding and awareness of practices that may be presented to individualgrowers, packers, and shippers for consideration and incorporation into their ownoperations.

Users of the Guide are reminded of several important considerations in applying itsrecommendations. These considerations also are important for those using thismanual:

1) The manual focuses on microbial hazards for fresh produce. It addresses in only

the broadest terms other areas of concern to the food supply or the environment(such as pesticide residues or chemical contaminants). When providingrecommendations to growers, packers, and shippers it is important toencourage them to apply the techniques that are most appropriate for reducinghazards in their individual operations. They should also strive to establishpractices that do not inadvertently increase other risks to the food supply or theenvironment (e.g., excessive packaging or improper use and disposal of


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antimicrobial chemicals).

2) This training manual focuses on risk reduction not risk elimination. Currenttechnologies cannot eliminate all potential food safety hazards associated with

fresh produce that will be eaten raw.3) This training manual provides broad, scientifically-based principles. Trainers

should encourage operators to use the information to help assessmicrobiological hazards within the context of the specific conditions (climatic,geographical, cultural, economic) that apply to their own operation andimplement appropriate and cost effective risk reduction strategies.

4) Users of the manual should constantly be alert for new information andtechnological advances that expand the understanding of those factorsassociated with identifying and reducing microbial food safety hazards.

Awareness of these advances will allow updating the recommendations and

information contained in this manual as appropriate to keep training contentcurrent.


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ACRONYMS

The following acronyms are used in this manual. Each is identified when first

introduced in the text but are also listed here for easy reference.

APHIS – Animal and Plant Health Inspection Service/U.S. Department of Agriculture

CAC- Codex Alimentarius Commission

CCP – Critical Control Point

CDC – U.S. Centers for Disease Control and Prevention

CFR – Code of Federal Regulations

CFSAN – Center for Food Safety and Applied Nutrition/U.S. Food and Drug Administration

CODEX ALIMENTARIUS – a code of food standards for all nations

CSREES – Cooperative State Research, Education and Extension Service/U.S.Department of Agriculture

EPA – U.S. Environmental Protection Agency

FAO – Food and Agriculture Organization of the United Nations

FDA – U.S. Food and Drug Administration

GAPs - Good Agricultural Practices

GATT- General Agreement on Tariff and Trade

GDP- Gross Domestic Product

GMPs - Good Manufacturing Practices

HACCP - Hazard Analysis Critical Control Point

IFSE – Institute of Food Science and Engineering/University of Arkansas


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IPM – Integrated Pest Management

JIFSAN – Joint Institute of Food Safety and Applied Nutrition/University of Maryland

MAQ – Minimum Acceptable Quality

PAHO – Pan American Health Organization

OSHA – Occupational Safety and Health Administration

SOPs – Standard Operating Procedures

SPS – Agreement on Sanitary and Phytosanitary Measures

SSOPs – Sanitation Standard Operating Procedures

TBT – Agreement on Technical Barriers to Trade

USDA – U.S. Department of Agriculture

USDA-AMS – USDA’s Agricultural Marketing Service

WHO – World Health Organization of the United Nations

WTO – World Trade Organization of the United Nations


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SECTION ITHE IMPORTANCE OF TRAINING FOR

IMPROVING THE S AFETY AND QUALITY OFFRESH FRUITS AND VEGETABLES

Copyright © 2002 University of Maryland. This work may be reproduced andredistributed, in whole or in part, without alteration and without prior writtenpermission , for nonprofit administrative or educational purposes provided allcopies contain the following statement: “© 2002 University of Maryland. This

work is reproduced and distributed with the permission of the University of Maryland. No other use is permitted without the express prior written permissionof the University of Maryland. For permission, contact JIFSAN, University of Maryland, Symons Hall, College Park, MD 20742


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Visual I.1-1

A hazard is something that could cause harm to the consumer. There are threemain types of hazards associated with fresh produce:• Biological hazards• Chemical hazards

• Physical hazards

Biological Hazards

Foodborne microorganisms such as bacteria, viruses and parasites are oftenreferred to as biological hazards (FAO, 1998). Some fungi are able to producetoxins and also are included in this group of hazards.

Visual I.1-2

Microorganisms are small organisms that can only be observed through amicroscope. Many of these organisms consist of a single cell. They can be foundeverywhere in the environment. Some have the ability to take up nutrients andmetabolize them into a large number of end products. Microorganisms often havethe ability to react to changes in their environment and some have been known toadapt to new environments.

Hazard - something that could cause harm to the consumer.

There are three main types of hazards associated with fresh produce:

• Biological hazards• Chemical hazards• Physical hazards

Microorganisms

Microorganisms are small organisms that can be observed through a microscope.

In order to facilitate the study of microorganisms they are divided into five major classifications:

• Bacteria• Yeasts• Molds• Parasites• Viruses


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Many microorganisms are beneficial to humans. Some are involved in theproduction of fermented foods such as bread, cheese, wine, beer, andsauerkraut. Other microorganisms are used by industry in the production of suchproducts as some enzymes, antibiotics, and glycerol. Additional microbial

functions such as degradation of organic matter and enrichment of soils alsobenefit mankind. However, some microorganisms have the potential for causingfoodborne illnesses.

Microorganisms able to cause human disease may be found on raw produce.Sometimes they are part of the fruit or vegetable microflora as incidentalcontaminants from the soil, dust and surroundings. In other instances they getintroduced onto the food through poor production and handling practices such asthe application of untreated manure, the use of contaminated irrigation water or unsanitary handling practices.

Bacterial Hazards

Because bacterial pathogens are part of the environment, they can easilycontaminate fruit and vegetables when these commodities are not properlyhandled prior to consumption. A list of bacterial pathogens that have beenisolated from raw produce can be found in Table 1 in the Additional Resourcessection. A thorough discussion of the pathogenic microorganisms associated withfood may be found in the FDA/CFSAN Bad Bug Book (FDA, 2001).

Visual I.1-3

A large number of bacterial pathogens have been implicated in foodborneoutbreaks associated with the consumption of fresh fruits and vegetables(Beuchat, 1998). Table 2 in the Additional Resources section provides a list of many of these outbreaks and the organisms associated with them.

Bacteria such as Clostridium botulinum, Bacillus cereus and Listeriamonocytogenes can be found in the soil and can easily contaminate produce.

Pathogenic bacteria associated with fruits and vegetables include:• Salmonella• Shigella• Escherichia coli (pathogenic)• Campylobacter species• Yersinia enterocolitica• Listeria monocytogenes• Staphylococcus aureus• Clostridium species• Bacillus cereus• Vibrio species


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Other bacteria such as Salmonella, Shigella, pathogenic Escherichia coli andCampylobacter reside in the intestinal tract of animals and/or humans. They cancontaminate fruit and vegetables through infiltration of sewage waters into fields,irrigation with contaminated water, presence of animals in the field or inappropriate composting. Contamination also can take place during handling at

harvest and packaging and in other steps in the distribution and marketing chain.

The number of bacteria that must be present to cause human illness varies withorganism type and age and condition of the host. In some instances it isnecessary to have over a million pathogenic bacteria per gram or cm2 of foodsurface before any illness occurs. However some pathogens are able to causedisease at much lower numbers. For example, Shigella spp. are highly infectiousagents with an infective dose of as few as 10 cells.

Because some bacteria have such low infective doses, prevention of bacterialcontamination is the most important control factor to enhance produce safety. It

is also important to take steps to assure that pathogens present cannotreproduce to hazardous levels.

Visual I.1-4

In order to reproduce bacteria require adequate nutrients and appropriateenvironmental conditions such as humidity, oxygen and temperature (FDA,1998). Each type of bacterium has specific requirements to achieve optimumdevelopment, but bacteria can multiply and cause disease outside of theseoptimum conditions. For example, for most rapid growth, E. coli requires atemperature of 37°C (98.6 °F). It can, however, multiply in a range of 10o to 46°C(50o to 114.8 °F). Bacillus cereus has an optimal growth temperature of 30°C, butcan grow in the temperature range of 10o to 49°C (50o to 120.2 °F) (Frazier andWesthoff, 1991).

To prevent pathogen reproduction in produce, control:• Nutrient availability• Humidity• Acidity• Temperature• Oxygen


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Visual I.1-5

Bacteria reproduce through a mechanism referred to as binary fission. Duringthis process, each cell divides in two. These two cells then divide in two and soon. When conditions are appropriate, a bacterial population can grow rapidly in avery short time.

Visual I.1-6

Time (hrs) # of bacteria

0 11 82 323 2564 2,0485 16,3846 131,0727 1,048,5768 16,777,2169 134,217,728

10 1,073,741,824

The time needed for a cell to divide (or a population to duplicate) is known asgeneration time. Generation times vary for different types of bacteria. Bacterialgeneration times depend to a large extent on nutrient availability andenvironmental conditions such as humidity, oxygen availability, acidity andtemperature. Consider E. coli which has a generation time that ranges between15 and 20 minutes. Under optimum conditions, in 10 hours a single cell couldproduce over a million cells.

When conditions for reproduction are favorable, bacterial cells start their

multiplication process. This process usually takes place in a series of steps or phases. In general, the bacterial reproduction process for a given population of cells follows a pattern similar to that illustrated in Visual I.1-7.

In 7 hours one bacteria cell cangenerate over a million bacteriacells

Bacterial reproductionscheme:Each bacterial cell

divides into two whenconditions areappropriate for itsgrowth


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Visual I.1-7

Knowledge of the population growth process provides insight into opportunitiesfor prevention and control of bacterial growth. In order to keep bacterial numbersfrom reaching levels that can be a threat to human health, it is necessary to keepthe initial numbers low and to assure that organisms that reach the product arenot allowed to grow beyond the lag phase.

Some of the control strategies that will be discussed in this course are preventiveand attempt to maintain low initial numbers of microorganisms. These includeGood Agricultural Practices like controlling microbial hazards from water, proper use of manure and biosolids, appropriate worker hygiene and provision of worker sanitation facilities, and proper sanitation during product handling andtransportation. Other recommendations such as temperature control and some of the more novel technologies are used to slow bacterial growth.

A processing step which can lower initial bacterial numbers is washing, providedwash water is of good quality and is not allowed to accumulate dirt andcontaminants. The surface of a well-washed tomato may have less than 1000microorganisms per square centimeter, while an unwashed one may have aseveral thousand. Before washing, the number of microorganisms on theexternal tissue of cabbage could be as high as one or two million per gram.Washing decreases this number to the range of 200,000 to 500,000 (Frazier andWesthoff, 1991).

(4) Stationary Phase

(2) Positive Growth Phase

(1) Lag or Latent Phase

Time

Number of bacteria

(5) Death Phase

(3) Logarithmic or ExponentialGrowth Phase


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Viral Hazards

Visual I.1-10

Viruses are very small and unable to reproduce outside of a living cell. Thereforethey do not grow in or on foods. However, raw fruits and vegetables may becomecontaminated by exposure to contaminated water or during handling by infectedpeople. The viruses infect susceptible persons consuming the raw produce.Since an infective dose of most viruses is extremely small, sometimes as few as

10 virus particles, prevention of produce contamination is critical to controllingviral disease.

Sources of Biological Hazards

Characteristics of some of the microorganisms causing disease in humans aredescribed in Table 1 in the Additional Resources section. Also presented areexamples of sources of contamination and symptoms associated with theillnesses they cause. Diagnosis of these illnesses requires clinical testing,however, recognizing the symptoms associated with various forms of contamination can aid in preventing contamination by providing a means of

identifying potentially infected handlers so that their contact with fresh producecan be avoided.

Many of the diseases caused by pathogenic bacteria, parasites, and viruses thathave been linked to fruits and vegetables can be transmitted when human fecescontaminate the produce. It is important that individuals handling produce atevery stage, from field to table have a good understanding of proper hygienepractices to prevent contamination. Training of workers at every level of theproduction chain and education of consumers have been identified as keyelements to reduce foodborne illnesses associated with fresh fruits andvegetables (Beuchat, 1998).

Chemical Hazards

Chemical contaminants in raw fruits and vegetables may be naturally occurringor may be added during agricultural production, post-harvest handling and other unit operations (FAO, 1998). Harmful chemicals at high levels have beenassociated with acute toxic responses and with chronic illnesses.

Viruses that have been reported as transmitted by foods include:• Hepatitis A• Norwalk virus and Norwalk-like virus• Rotaviruses, astroviruses, enteroviruses (polioviruses, echoviruses and

coxsackie viruses), parvoviruses, adenoviruses and coronaviruses.


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Visual I.1-11

Visual I.1-12

Data collected by the WHO Food Contamination Monitoring and AssessmentProgram (GEMS/Food) indicate that, in many countries, chemical contaminationlevels are tending to decline. This is due, in large part, to increased restriction onthe use of toxic chemicals and pesticides that persist in the environment and to

improved control of environmental pollution.

Physical Hazards

Physical hazards may be introduced into fresh fruit and vegetable products atnumerous points in the production chain.

Added Chemical Hazards

Polychlorinated biphenyls (PCBs) Contaminants Agricul tural chemicals § Lubricants§ Pesticides § Cleaners§ Fertilizers § Sanitizers§ Antibiotics § Coatings

Prohibited substances § Paints§ Direct § Refrigerants§ Indirect § Water or steam treatment

chemicals

Toxic elements and compounds § Pest control chemicals§ Lead From packaging materials§ Zinc § Plasticizers§ Cadmium § Vinyl chloride§ Mercury § Painting/coding inks§ Arsenic § Adhesives§ Cyanide § Lead

§ Tin

Some Naturally OccurringChemicals Hazards

• Allergens (e.g. weeds)• Mycotoxins (e.g. aflatoxin)• Mushroom toxins• Phytohaemagglutinin• Alkaloids


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Visual I.1-13

Illness and serious injuries can result from foreign material in produce. Thesephysical hazards can result from poor practices during harvesting, washing,sorting and packaging operations (FAO, 1998). Filth and foreign matter in fruitand vegetables are listed, in many instances, among the main barriers for international trade.

Summary

1. A hazard is something that could cause harm to the consumer. There arethree main types of hazards associated with fresh produce:• Biological hazards• Chemical hazards• Physical hazards

2. Foodborne microorganisms such as bacteria, viruses and parasites are oftenreferred to as biological hazards. Some fungi are able to produce toxins andalso cause a hazard.

3. Microorganisms able to cause human disease may be found on raw produce.Sometimes they are part of the fruit or vegetable microflora as incidental

Material Injury potential SourcesGlass Cuts, bleeding; may require

surgery to find or remove

Bottles, jars, light,

fixtures, utensils,gauge, covers, etc.

Wood Cuts, infection, choking; mayrequire surgery to remove

Field sources, pallets,boxes, buildingmaterials

Stones Choking, broken teeth Fields, buildings

Insulation Choking long-term if asbestos

Building materials

Plastic Choking, cuts, infection; mayrequire surgery to remove

Packaging, pallets,equipment

Personaleffects, i.e.

jewelry, hair clips, pens

Choking, cuts, broken teeth;may require surgery toremove

Employees


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contaminants from the soil, dust and surroundings. In other instances they getintroduced into the food through poor production and handling practices suchas the application of untreated manure, the use of contaminated irrigationwater or unsanitary handling practices.

4. Fresh fruits and vegetables may be vehicles for the transmission of parasitesand viruses.

5. Training of workers at every level of the production chain and education of consumers have been identified as key elements to reduce microbial hazardsassociated with fresh fruits and vegetables.

6. Chemical contaminants in raw fruits and vegetables may be naturallyoccurring or may be added during agricultural production, post-harvesthandling and other unit operations.

7. Illness and serious injuries can result from foreign material in produce. Thesephysical hazards can result from poor practices during harvesting, washing,sorting and packaging operations.


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Module 2Fresh Produce Safety and Consumer Health *

Learning Outcome

Ø Participants will gain greater awareness of the consequences of foodbornedisease.

Practical

Ø Discussion Question 2

In 1983, the Expert Committee on Food Safety convened jointly by the World

Health Organization (WHO) and Food and Agricultural Organization (FAO) of theU.N. concluded that illness due to contaminated food is “the most widespreadhealth problem in the contemporary world” (FAO/WHO, 1984).

Despite efforts to reduce foodborne illnesses, there are still significant healthhazards associated with food.

Visual I.2-1

The relative importance of these hazards can be determined by studying diseasesurveillance data. Data from Latin America and the Caribbean reveal that almosthalf of all foodborne diseases with identifiable sources were caused by microbialsources and bacterial pathogens represented the largest single share of allknown sources (PAHO/WHO, 1998). In the U.S during 1993-1997, a total of

* Prepared by: Pamela Brady, Ph.D., IFSE, University of Arkansas

Sources of Foodborne Disease Outbreaks in Latin America and theCaribbean – 1995-1997

Agent % Cases

Bacteria 46.3Viruses 1.8Parasites 1.8Total Microbial 49.9

Marine Toxins 44.2Plant Toxins 0.4Chemicals 5.4


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2,751 outbreaks of foodborne disease (two or more cases of a similar illnessresulting from the ingestion of a common food) were reported (Olsen et al.,2000). These outbreaks caused a reported 86,058 persons to become ill. Amongoutbreaks for which the cause was determined, the largest percentage of bothoutbreaks (75%) and cases (86%) were caused by bacterial pathogens.

Chemical agents caused 17% of outbreaks and 1% of cases; viruses, 6% of outbreaks and 8% of cases; and parasites, 2% of outbreaks and 5% of cases.

According to the U.S. Centers for Disease Control and Prevention (CDC),produce-associated foodborne disease outbreaks are a relatively smallpercentage of all foodborne disease. However, the number of cases isincreasing. In 1973-1979, only 2% of U.S. foodborne disease outbreaks wereassociated with fresh produce. In 1990-1997, this had increased to 6%. Of theseproduce-related outbreaks, 50% were attributed to bacterial contamination, 7% toviruses, 6% to parasites, and 35 % to unidentified causes (Liang, 2000).

Visual I.2-2

Despite efforts to decrease the occurrence of these diseases, it is estimated that5 to 10% of the populations in developed countries suffer from foodborne illnesseach year and the numbers are even higher in less developed areas (Kaferstein,et al. 1997). Since many of these illnesses are not reported to public health

officials, it is difficult to get an exact count on actual numbers. However, statisticsfrom both developed and developing countries show a trend toward morefoodborne illnesses in recent years. In part, this trend may be due toimprovements in disease reporting systems in some countries. However, mostauthorities agree that there also is an increase in the actual number of cases.

Incidences of Foodborne Diseases in Venezuela


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Health Effects of Foodborne Disease

Visual I.2-3

For most adults in the industrialized world, incidents of foodborne disease areunpleasant but are generally mild and self-limiting (WHO, 1999a). Symptoms aregenerally restricted to gastroenteritis and are not usually life-threatening.

However, for susceptible individuals, such as the elderly, pregnant women, thevery young, and those with compromised immune systems, foodborne illnessmay lead to serious consequences including death.

In developing countries, diarrheal diseases, particularly infant diarrhea, are amajor public health problem. It has been estimated that annually over 1,500million children under the age of five years suffer from diarrhea and over 3 milliondie as a result (WHO, 1999a). Diarrhea may also lead to malnutrition that canmake children more susceptible to longer periods of diarrhea and to infections.These occurrences can lead to a downward spiral of poor health and, eventually,to premature death.

Not all foodborne disease results in intestinal illnesses (WHO, 1999a). The WHOestimated that 2-3% of the cases of foodborne illness lead to other conditions,which may result in chronic diseases having long-term effects on those afflictedand/or death. Clostridium botulinum causes a severe neuroparalytic disease thatis often fatal. Effects of Listeria monocytogenes can vary from mild flu-likesymptoms to meningitis and meningoencephalitis. This organism is especiallyserious for pregnant women since infection may result in abortion, stillbirth, or premature labor. For persons with compromised immune systems, infectionsmay result in serious illness and even death.

Some Effects of Foodborne Disease

• Vomiting• Gastroenteritis• Diarrheal disease• Non-intestinal disease, i.e. neurological conditions, pre-mature labor, and still-

births


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Costs of Foodborne Disease

Visual I.2-4

Although the difficulty in identifying the actual number of cases of foodborneillness makes it hard to estimate the cost of these diseases, no one can disputethat foodborne illness is very expensive. The economic impacts affect not onlythe individuals and families involved but also the communities, industries, andnations (Doores, 1999). The most obvious costs are those associated with healthcare for the afflicted individuals. Additional costs related to caring for those whoare ill, absenteeism from work and school, and travel costs to seek medical careadd to the financial burden. Costs to society include lost worker productivity, thecosts of investigating and controlling outbreaks, lost revenue due to businessclosure and product avoidance, legal costs for litigations related to the illnesses,and costs related to public services for those suffering from chronic disease.

One study estimated that, in the U.S., the cost of foodborne disease caused byseven common pathogens was US$ 5.6 to 9.4 billion (WHO, 1999b). Theestimated cost of salmonellosis in England and Wales in 1992 was placed atUS$560 to 800 million.

Fresh produce is a particular food safety concern since it is generally eatenwithout any processing to eliminate or reduce the number of microorganismspresent. In addition, since the 1980’s, several foodborne infectious agents havebeen either newly described or newly associated with fruits and vegetables(Tauxe, 1997). For example E. coli O157:H7 was first identified as a pathogenassociated with hamburger in 1982. In 1993, an outbreak of disease caused bythis organism in unpasteurized apple juice demonstrated that it could survive in alow acid environment.

Costs of Foodborne Disease

Costs for Individuals Cost to Society3 Medical costs 3 Loss of productivity3 Missed work and lost wages 3 Cost of disease investigation3 Travel to get care 3 Loss of revenue due to business

closure and product avoidance3 Expenses for care taker 3 Chronic disease3 Chronic disease


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Summary

1. A majority of foodborne illness for which causes have been identified havebeen associated with biological hazards.

2. Produce-associated foodborne disease outbreaks are a relatively smallpercentage of all foodborne disease however, the number of cases isincreasing.

3. For susceptible individuals, such as the elderly, pregnant women, the veryyoung, and those with compromised immune systems, foodborne illness maylead to serious consequences including death. It has been estimated thatannually over 1,500 million children under the age of five years suffer fromdiarrhea and over 3 million die as a result.

4. Costs related to foodborne illness include caring for those who are ill,

absenteeism from work and school, travel costs to seek medical care, lostworker productivity, the costs of investigating and controlling outbreaks, lostrevenue due to business closure and product avoidance, legal costs for litigations related to the illnesses, and public services for those suffering fromchronic disease.


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Module 3Impact of Produce Safety on Trade*

LEARNING OUTCOME

Ø Participants will increase their knowledge of the impact of produce safety on acountry’s economy.

PRACTICAL

Ø Discussion Question 1.

The effects of unsafe fruits and vegetables on health are important reasons for studying produce safety but they are only part of the cause for concern about the

safety of these products.

Visual I.3-1

Food and agricultural production plays an important role in the economy of manycountries, especially those of Latin America and the Caribbean. 1999 figuresindicated that, depending on the country, total agriculture (production of bothfood and non-food crops of plant and animal origin) contributed from as little as2% to over 34% of the gross domestic product (FAOSTAT, 2000). These figuresrepresented not only the value of products but also income generated by persons

* Prepared by: Pamela Brady, Ph.D., IFSE, University of Arkansas

Economic Impact of Agriculture

Country 1999 GDP*(billion$)

GDP -agriculture

Employmentin agriculture

Belize 0.74 22% 38%Brazil 1,057.00 14% 31%Chile 185.10 6% 14%Costa Rica 26.00 14% 20%Dominican Republic 43.70 14% 17%Guatemala 47.90 23% 50%Mexico 865.50 5% 24%Nicaragua 12.50 34% 42%Trinidad & Tobago 9.41 2% 10%

* GDP = Gross Domestic Product


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employed in the agricultural sector. For many countries in the region a significantproportion of the population is employed in agriculture.

Trade is an important part of the economy of most countries and agriculturalproducts make up a significant portion of this trade. According to the World Trade

Organization (WTO), total world trade in 1999 was valued at $5,473 billion withapproximately 10% of this total, or $544 billion, in agricultural products (WTO,2000).

Visual I.3-2

In 1999, exports of agricultural products from countries in Latin America and theCaribbean were valued at over $36 billion (WTO, 2000). For some countries,exports of fruits and vegetables made up close to half of the total agriculturalexports. Thus, assuring the acceptability of these products to importing countriesis a major economic consideration. In addition, it is important keep in mind thatfruits and vegetables are produced for domestic consumption as well as for export. Therefore, the production of safe products is important for the health andwelfare of the people within a country as well as for potential export revenue.

The safety of foods has a wide reaching effect on world trade. The World HealthOrganization estimated that in 1993, foodborne diseases produced worldwide

losses in international food trade of approximately US$380 million (PAHO/WHO,1998). In addition to the economic burden on those afflicted with disease,foodborne illness also led to economic effects on industry and healthcaresystems.

Countries importing product have strong economic reasons for demanding safeproduct. Unsafe imports may pose a threat to the health and safety of consumers. Detention and/or rejection of unsafe product and decreased

1999 Export Values from Selected Countries (1000$ U.S.)

ProduceCountry Total Agriculture Total %

Agriculture

Belize 108,299 59,007 54%Brazil 13,824,401 1,690,870 11%Chile 2,966,674 1,804,797 52%Costa Rica 1,802,773 927,902 51%Dominican Republic 332,094 66,155 20%Guatemala 1,431,210 276,827 19%Mexico 7,006,363 3,213,241 46%Nicaragua 312,854 34,109 11%Trinidad & Tobago 221,261 20,400 9%


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consumer confidence in a product or in a country’s ability to produce safe productcan lead to major losses of revenue for both exporting and importing countries.These lost markets and decreased revenues can translate to reduced communityservices, lower wages, and lost jobs. An example of this was seen with the 1996U.S. outbreak of Cyclospora. Preliminary investigation identified domestic

strawberries as the vehicle for this outbreak. Although further investigationproved the source of the outbreak was imported raspberries, the CaliforniaStrawberry Commission reported that decreased consumer confidence in productsafety resulted in over $40 million in lost revenue, 5,000 lost jobs, and a 10%reduction in crop acreage the following year (CDFA, 1997).

In the U.S., consumers are demanding year-round access to fresh fruits andvegetables. Produce from Latin America and the Caribbean helps meet thisdemand since much of it arrives when cold weather prevents the production of produce domestically (Zepp, et al., 1998). In 1998, U.S. fresh produce importsreached record levels with values totaling over $2.7 billion for fresh fruits and

$2.1 billion for fresh vegetables (FASonline, 1999). Countries in Latin Americaand the Caribbean supplied over 80 percent of the U.S. imported fruits and over 70 percent of the imported vegetables.

Visual I.3-3

Although the number of foodborne illness outbreaks associated with freshproduce is still relatively low, as produce consumption has increased, there hasbeen a greater incidence of foodborne illness outbreaks associated with freshfruits and vegetables (Guzewich and Salsbury, 2000). Some of these outbreakshave been associated with imported produce. However, the proportion of foodborne illness associated with imported produce is no greater than that fromproduce grown in the U.S.

Examples of Recent U.S. Multistate Foodborne Disease Outbreaks Associated wi th Fresh Produce

Year # of States

# of Cases

Pathogen Associated food

2001 6 >40 Salmonella Cantaloupe2000 8 86 Salmonella Tomatoes1998 3 >400 Shigella Parsley1997 14 864 Cyclospora Berries1997 3 305 Cyclospora Basil1996 2 49 E.coli O157:H7 Leaf lettuce1996 2 72 Shigella Scallions1996 20 1,500 Cyclospora Raspberries1993 3 84 Salmonella Tomatoes1991 23 400 Salmonella Cantaloupe


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When looking at the safety record of produce exported to the U.S., it is importantto consider that although disease outbreaks may have been associated withproduce from another country, the actual site of contamination may never bedetermined. This is because product contamination can occur anywhere in theproduction and marketing chain (Zepp et al., 1998). Furthermore, by the time an

outbreak is traced to a farm, packinghouse or other site, the actual source of contamination may no longer be there. An example of this problem was seen in a1991 Hepatitis A outbreak associated with frozen strawberries. The berries weregrown in Mexico and processed and distributed in the United States. Outbreakinvestigators were unable to determine if the contamination occurred before theberries entered the U.S. or during processing and distribution (See Table 2 in

Additional Resources section for a list of produce-related outbreaks in the U.S.).

Summary

1. Food and agricultural production plays an important role in the economy of many countries.

2. Exports of fruits and vegetables make up a large percentage of the exportincome of many countries in Latin America and the Caribbean.

3. Unsafe imports may pose a threat to the health of the people consuming themand result in significant economic loss for the exporting country.

4. Foodborne disease outbreaks in the U.S. have been associated with producefrom both domestic and imported sources. The proportion of foodborneillnesses associated with imported produce is no greater than that fromproduce grown in the U.S.


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REFERENCES

Beuchat, L.R. 1998. Surface decontamination of fruits and vegetables eaten raw:a review. World Health Organization. WHO/FSF/FOS/98.2. Available viathe Internet at http://www.who.int/fsf/fos982~1.pdf

CDFA. 1997. Secretary praises strawberry industry for establishing voluntaryquality assurance program. California Department of Food and AgriculturePress Release, 1/27/97.

Doores, S. 1999. Food Safety – Current Status and Future Needs. Amer. Academy of Microbiology Report. p. 21.

FAO. 1998. Food Quality and Safety System: A training manual on food hygieneand the Hazard Analysis and Critical Control Point (HACCP) system.Publishing Management Group, FAO Information Division, Rome.

FAO/WHO 1984. The role of food safety in health and development. Report of Joint FAO/WHO Expert Committee on Food Safety. WHO Tech. Rep:705.

FAOSTAT. 2000. Agriculture Data. FAO. http://apps.fao.org/page/collections?subset=agriculture

FASonline. 1999. Fruit and Vegetable Imports – Calendar Year 1998. USDA/FASHorticultural and Tropical Products Division. Available via the Internet atwww.fas.usda.gov /htp2/highlights/1999/99-04/fvimp98/fvimpCY98.html

FDA. 1998. Guide to minimize microbial food safety hazards for fresh fruits andvegetables. U.S. Food and Drug Administration. Available via the Internetat http://www.cfsan.fda.gov/~dms/prodguid.html

FDA. 2001. Foodborne Pathogenic Microorganisms and Natural ToxinsHandbook – The “Bad Bug Book.” U.S. Food and Drug Administration-Center for Food Safety and Applied Nutrition. Available via the Internet athttp://www.cfsan.fda.gov/~mow/intro.cfm

Frazier and Westhoff, 1991. Microbiología de los Alimentos. Tercera Edición.Editiorial Acribia, S.A. Zaragoza, Spain. pp. 439.

Guzewich, J.J. and Salsbury, P.A. 2000. FDA’s role in traceback investigationsfor produce. Food Safety Magazine. December, 2000/January, 2001.

Kaferstein, F. K., Motarjemi, Y., and Bettcher, D. W. 1997. Foodborne diseasecontrol: A transnational challenge. Emerging Infectious Diseases 3(4) 503.


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Liang, A.P. 2000. The epidemiology of produce-related outbreaks in the UnitedStates. Presentation at the IFT Food Safety Conference, Orlando, FL.

Murray, P., Drew, W., Kobayashi, G. and Thompson, J. 1995. MedicalMicrobiology. Mosby-Doyma Libros, S.A. Madrid, Spain. pp. 423.

Olsen, S.J., MacKinon, L.C., Goulding, J.S., Bean, N.H. and Slutsker, L. 2000.Surveillance for Foodborne Disease Outbreaks --United States, 1993-1997. Morbidity and Mortality Weekly Report Surveillance Summary49(SS01): 1.

PAHO/WHO. 1998. Health in the Americas. 1998 edition – Vol. 1. Pan AmericanHealth Organization/World Health Organization Scientific Publication No.569.

Tauxe, R.V. 1997. Emerging foodborne disease: An evolving public health

challenge. Emerg Infect Dis 3(4):425.

WHO. 1999a. Basic Food Safety for Health Workers. World Health Organization.WHO/SDE/PHE/FOS/99.1.

WHO. 1999b. Food Safety – An Essential Public Health Issue for the NewMillennium. Food Safety Program, Depart of Protection of the HumanEnvironment, World Health Organization, WHO/SDE/PHE/FOS/99.4.

WTO. 2000. International Trade Statistics 2000. World Trade Organization,Geneva, Switzerland. Available via the Internet atwww.wto.org/english/res_e/statis_e/stat_toc_e.htm

Zepp, G, Kucher, F. and Lucier, G. 1998. Food safety and fresh fruits andvegetables: Is there a difference between imported and domesticallyproduced products? Vegetables and Specialties, Economic ResearchService/USDA, VGS-274:23.


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SECTION IIGOOD AGRICULTURAL PRACTICES*

Copyright © 2002 University of Maryland. This work may be reproduced andredistributed, in whole or in part, without alteration and without prior writtenpermission, for nonprofit administrative or educational purposes provided allcopies contain the following statement: “© 2002 University of Maryland. Thiswork is reproduced and distributed with the permission of the University of Maryland. No other use is permitted without the express prior written permissionof the University of Maryland. For permission, contact JIFSAN, University of Maryland, Symons Hall, College Park, MD 20742

* Section prepared by: Carmen Hernandez-Brenes, Ph.D., ITESM-Campus Monterrey, Mexico


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Introduction*

Produce may become contaminated with pathogens anywhere in the farm-to-table chain. If produce becomes contaminated, there is no process other thanthorough cooking to ensure elimination of the pathogens. Since cooking is notappropriate for produce bound for fresh markets, prevention of contamination isimperative to assure a safe product.

The use of Good Agricultural Practices (GAPs) during growing, harvesting,

sorting, packaging, and storage operations for fresh fruits and vegetables is keyto preventing pathogen contamination. Key areas of concern when implementinga GAP program are prior land use, adjacent land use, water quality and usepractices, soil fertility management, wildlife, pest, and vermin control, worker hygiene and sanitary facilities, and harvesting and cooling practices.

The following modules provide a look at these operations and the GAPsassociated with each. The intent of this manual is not to cover every detail of each operation in the production and handling of fresh produce but rather toeducate on the importance of the topic and to use pertinent examples to illustratesome concerns. Because of the diversity of agricultural production practices and

commodities, procedures recommended to minimize microbial contamination willbe most effective when these general concepts are adapted to specificoperations.

* Section prepared by: Carmen Hernandez-Brenes, Ph.D., ITESM-Campus Monterrey, Mexico

SECTION II

Good Agricultural Practices


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Module 1Soil and Water

Learning Outcomes

Ø Participants should be able to identify the potential for produce contaminationresulting from current and prior uses of the soil.

Ø Participants should be able to recognize the potential for producecontamination associated with water quality and use practices.

Practical

Ø Laboratory Exercise: Water as a Contamination Agent

Addi tional Resources

Ø Part III – Disinfecting Contaminated Wells

In order to reduce risks associated with the production of fresh fruits andvegetables, it is necessary to first assess the potential hazards in the productionenvironment. Once the potential sources of produce contamination have beenidentified, practices should be implemented to reduce or eliminate them.

For example, human and animal feces are one of the most important sources of contamination of soil and water. This contamination can be easily spread to fresh

produce. When assessing the possible produce contamination associated with aproduction site, it is important to look at the potential for fecal contamination and,if it exists, to determine steps to eliminate this hazard source.

Soil

Agricultural land and land that has been used for activities other than agriculturecan be contaminated with pathogenic organisms or toxic chemical substances.Obtaining a history of the prior use of the land is important because it helpsidentify these potential hazards. In addition, the failure of prior users to followGood Agricultural Practices can offer risks of contamination to produce grown on

the soil.Visual II.1-1

Identification Of Hazards Associated With Soil History

As part of a Good Agricultural Practice (GAP) program it is necessary to identifypossible sources of microbial and chemical contamination associated with theprior use of land that it is being used for agricultural production.


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It is important to obtain information about the previous use of the land whereagricultural production is taking place. This can be done through interviews withprior owners, a review of municipal permits or from other sources. Thisbackground information can help in the identification of situations that can

increase the risk for fresh produce contamination (FDA, 1998).

Visual II.1-2

Prior use of the land for animal feeding or domestic animal production can greatlyincrease the risk of contamination of fruit and vegetables with pathogenscommonly found in the intestinal tract of animals. The potential for contaminationfrom this source is related to the time that has passed since the land was usedfor animal feeding or production. The risk of contamination will also be influencedby conditions such as atmospheric temperature, sunlight and relative humidity.

The presence of barns or farm animals a short distance from the cultivation siteincreases the risk of product contamination. Assessment of the location of the

animals and their facilities and evaluation of drainage systems and water currents flowing near these areas will help determine the potential for contamination. In some instances it may be necessary to create physical barriersor channels to divert water which may carry contamination from the animals.

When the land has been used for garbage disposal or as a waste managementsite, it may contain decomposing organic matter and, perhaps, fecal material.

Cultivated Land Information

Important information that needs to be obtained about the history of the landincludes if the land has been used:• For animal feeding• For domestic animal production• As a garbage or toxic waste disposal site• As a sanitary waste management site• For mining activities, oil or gas extraction• For the disposal of incinerated material, industrial waste or if mineral residues

exist on the site• For barns and/or if farm animals are being produced on land adjacent to or a

short distance from the cultivation site.

Other information that should be obtained include if the land has:• Experienced any serious flooding.• Been treated in an uncontrolled manner with organic or inorganic fertilizers

and/or pesticides.


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Depending on the garbage contents, soil microbial loads can be extremely highand the soil may also contain harmful chemicals or toxic contaminants.

Land that has been used for mining or petroleum extractions can becontaminated with heavy metals or hydrocarbons. Even if the contamination is

located on a small portion of the land, factors such as rainfall and subterraneouswater flow should be evaluated. Analysis of toxic substances in the soil and areview of the environmental compliance of the extraction operation arerecommended when the ground history indicates a high risk for chemicalhazards.

Heavy flooding also can increase the sources of contamination. Water run-off can introduce pathogens and chemical contaminants from further regions. Deadanimals and still water remaining after the floodwaters have receded can lead tosignificant bacterial hazards. Individual assessment of each flooding situation willbe needed along with a review of the time that has passed since the flood and

other conditions that can mitigate or reduce the risks. When there is concernabout the safety of the growing site, microbiolgical analyses after a contaminationhas occurred (e.g. flooding or run-off) may assist in identifying contamination.

Even if the investigation of the prior use of the land indicates that it has beenused solely for agricultural production, prior production practices should bereviewed. Improper use of organic fertilizers may result in microbiologicalcontamination of the soil while inorganic fertilizer and/or pesticides usedimproperly can cause serious chemical hazards. Chemical compounds shouldhave been used according to label recommendations and the products should beregistered for use on the specific crop.

Visual II.1-3

The land owner or operator should research both the present and prior use of adjacent lands to identify potential produce contamination and precautions thatneed to be taken to prevent contamination of fresh produce in the field.

Contamination from areas away from the actual growing area can reach producethrough a variety of means including water or wind flow, and workers, vehicles, or equipment moving from one area to another.

Current or Prior Use of Adjacent Land

• Information about the use of land adjacent to the production site is critical sincethis helps identify situations that can increase the risk of contamination of freshproduce with pathogenic bacteria or toxic substances.

• Contamination can reach produce through a variety of means including water or wind flow, workers, vehicles, or equipment.


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Water Resources and Irrigation Practices

Visual II.1-4

During agricultural production of fruits and vegetables, water is used for numerous activities in the field, including irrigation and pesticide and fertilizer application (FDA, 1998). Other water uses during produce handling includecooling, washing, waxing and transportation. In addition to activities where water comes in direct contact with produce, field and packing shed workers use water for drinking and hand washing.

Visual II.1-5

Poor quality water may be a direct source of contamination and also an importantvehicle for spreading microorganisms in the production field (Bern et al., 1999).Every time water comes in direct contact with fruits or vegetables, the possibilityof contaminating the produce with pathogens exists. This includes water used for

produce production, fresh produce washing, in packaging facilities and duringtransportation. The severity of the hazard resulting from poor quality water willdepend on the type and number of microorganisms in the water and their capacity to survive on the produce.

Water used in the production of fruits and vegetables can be a source of pathogencontamination and dissemination.

Water used in agricultural activities can be contaminated with pathogenic bacteriathat may cause severe health problems to consumers.

It can be a source of and vehicle for biological hazards such as:

Enterohemorrhagic and Salmonella spp.Enterovirulent Escherichia coli Shigella spp

Vibrio cholerae Gardia lambliaCryptosporidium parvum Toxisplasm gondii

Cyclospora cayetanensis Hepatitis A virusNorwalk virus

Such microorganisms are associated with gastrointestinal diseases that, in severecases, can cause death.


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Visual II.1-6

In addition to the quality of the water other factors that can increase the risk of contamination of produce by water include the stage of development and type of crop, the time between the contact of the produce with the water and harvest,and other water and produce handling practices. Fruits and vegetables with largesurface areas, like leafy vegetables, or those where the surface structure allows

pathogens to adhere easily are at a greater risk of contamination from water.This risk can be further increased when the contact with contaminated water takes place near harvest time or during post harvest handling.

Potential Produce Contamination Associated with Water Sources

Visual II.1-7

Among the most common sources of agricultural water are surface rivers,streams, open canals, etc. Other sources include reservoirs such as swamps,lakes, tanks, ground water from wells (open or capped) and, occasionally, publicwater systems.

Surface and reservoir sources vary considerably in their microbial content.Microbial loads of surface water range from several thousand organisms per milliliter after a rainfall to a relatively low number after auto purification, anormally occurring process in smooth waters.

Surface waters can be exposed to temporary or intermittent contamination. Thiscontamination can come from raw human and animal wastes, sewage water discharges, and water coming from adjacent lots dedicated to animal productionor other contamination. Surface water generally flows some distances before itreaches the crop. It is important to identify upstream sources of contamination tothis flow. Elimination of this contamination may involve modification of the water’sroute or the introduction of intervention methods, such as filters.

The chances of contamination of fruits and vegetables with microorganismspresent in water can increase depending on factors such as:

• Product growth stage• Type of crop• Time between water application and harvest• Water and product handling practices

Usually, water for agricultural uses comes from:• Surface sources such as rivers, streams, and reservoirs• Ground water from wells (open or capped)• Public water s stems such as those rovided b towns or other munici alities


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Visual II.1-8

Water destined for agricultural production can easily become contaminated withhuman and/or animal feces. It is important to keep animals and children out of the fields and to provide field workers with properly constructed and maintainedrestrooms or mobile sanitary units. Water contamination with human fecal

material also can occur if wells and water systems are not properly developed, if septic systems fail or have deficiencies in their design, and from discharges thatcome from sewage treatment plants.

Wildlife, including insects, rodents, reptiles, and birds, can carry disease. Sincethese are found even in the most pristine environments, absolute protection of water is difficult and minimization of potential contamination by wildlife should bethe goal.

Visual II.1-9

It is generally believed that ground water is less likely than surface water to becontaminated with pathogens since ground water generally loses much of itsbacterial and organic compound content after filtration though rock and claylayers. (Buttler et al, 1993). The bacterial content of ground water may vary froma few to a few hundred organisms per milliliter. However, under certainconditions, such as with shallow, old, or improperly constructed wells, thepotential for contamination of ground water by surface water is a great risk.

Ground water may be contaminated by a variety of biological and chemicalhazards, which include:• Bacteria, viruses, parasites, and protozoans• Domestic waste• Nitrate nitrogen• Synthetic organic chemicals• Heavy metals• Petroleum residues• Combustion products from roadways

Water destined for agricultural production can easily become contaminated withhuman and/or animal feces.

To protect water sources:• Keep animals and children out of the fields;• Provide field workers with properly constructed and maintained restrooms or

sanitary mobile units;• Properly develop wells and water systems.


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Prevention of well contamination begins with proper placement of the well (Engelet al., 1998). The distance that the well must be from sources of contaminationdepends on many factors, such as geologic formations, depth of the aquifer,direction of groundwater flow, effects of well pumping on groundwater movement,and susceptibility of the site to flooding.

Both soil and slope characteristics make well location tricky. The followingstandards apply to the placement of wells (Engel et al., 1998):Ø The well should be located away from septic tanks, sewage disposal areas

(such as a drain field), and other sources of contamination such as feed lots,manure piles, chemical storage, chemical mixing areas, dumps or landfills,fuel storage tanks, storm sewers, privies, or refuse dumps. Separating thewell from a contamination source may reduce the chance of pollution, but itdoes not guarantee that it will be safe. Contaminants can come from greatdistances, depending on the depth of the aquifer and of the well.

Ø The well should be in an area free from flooding or extra precautions to

protect it must be planned. Floodwater can easily carry bacteria, oil products,and pesticides from one place to another.Ø Surface drainage should be planned to run water away from the well on all

sides. Up-slope drainage should be diverted away from hillside wells. A welldownhill from a barnyard, a leaking tank or a failing septic system runs agreater risk of contamination than a well on the uphill side of thesecontamination sources.

Ø The well should be located above (higher in grade) disposal areas if possible.Surface land slope does not always indicate the direction a pollutant mightflow once it gets into the ground. Groundwater often moves toward surfacestreams and lakes, but the aquifer supplying water to the well may be deepbelow the surface, and its slope may be different than the land surface.Finding out about groundwater movement on a farm may require specialmonitoring equipment.

Once the well site is selected and the well is in place, proper maintenance isimportant to assure the well water does not become contaminated. The well siteshould be kept clean and well casings, seals and caps should be maintained toprevent surface water and contaminants from entering the well. It is alsoimportant to consider that ground water is not inactive. Rain, snowmelt, or interchange with surface waters usually recharges a well. Because of this,human activities can lead to contamination of ground water.

Pesticide handling in the vicinity of wells may result in chemical contamination of ground water. The location of wells should be considered when mixing, applying,storing and disposing of pesticides. Vegetation or other barriers should beestablished as guard zones to help limit contact between the chemicals andwater sources (Nesheim, 1993).


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Visual II.1-10

Good agricultural practices also include the use of soil and water conservationpractices, such as channel construction, drain control structures, diversion tanks,vegetation barriers, etc., which act as physical barriers in the event of acontaminated water run off.

Hazards Introduced by Irrigation Practices

Visual II.1-11

Irrigation is the controlled application of water to the land or field with the purposeof providing the moisture levels required for the appropriate development of theplant. Irrigation plays a major role in achieving cultivable lands, especially in aridand semi-arid regions.

Visual II.1-12

Summary of GAPs to Prevent Contamination of Water Sources

• Identify the primary and secondary sources of water, and be conscious of sources for possible pathogen contamination.

• Identify sources of water shared with grass-lots, feed-lots and dairy farms.• Take necessary measures to prevent animal access to crop fields, water

sources and other related areas.• Be aware of uncontrollable wildlife vectors and treat water accordingly.• Identify if any adjacent fields are using untreated animal manure as fertilizer.• Avoid manure storage near the crop fields.• Identify topography of the landscape, its effect on water flow and the rainfall

pattern of the region.• Provide maintenance to water storage tanks.• Periodically verify water quality by submitting samples for microbiological

testing. Tests for standard indicators of fecal pollution, such as E.coli can be

performed but do not necessarily indicate the absence of protozoa and viruses.

Irrigation

Controlled application of water to the land or field with the purpose of providing themoisture levels required for the appropriate development of the plant.

Irrigation methods commonly used include:• Surface (furrow or flood)• Overhead (sprinklers)• Trickle (drip or buried)• Micro-s rinklers


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Irrigation methods commonly used include (Solomon, 1988; ERS, 2001):• Surface (furrow or flood) – where soil surface is used as a conduit for water

that is allowed to pond on the ground in furrows or throughout the field.• Overhead (sprinklers) – water is delivered through a pressurized pipe network

to sprinklers, nozzles or jets which spray the water into the air, to fall onto the

plants and soil in an artificial "rain".• Trickle irrigation - the slow, frequent application of water to the soil though

emitters placed at or near the root zone of the plants. The term trickleirrigation is general, and includes several more specific methods. Dripirrigation applies the water through small emitters to the soil surface, usuallyat or near the plant to be irrigated. Subsurface or buried irrigation is theapplication of water below the soil surface.

• Micro-sprinklers – are a cross between sprinkler and trickle irrigation. Thesesystems use low-volume sprinkler heads located about 1 foot above theground to spray water over a wide area when low volume overhead irrigationis desired. They are designed for areas where drippers are not practical, such

as large areas of ground cover or under trees. Their low-volume spray doesnot reach high into the air so plant material not growing close to the ground isnot directly exposed to the water.

Irrigation methods are selected according to the environment, water source,climate, soil characteristics, type of crop, and cost. The type of irrigation systemchosen is important to product safety since this determines the amount of contactbetween the irrigation water and the produce. In general, the quality of water indirect contact with the edible portion of produce may need to be better than thatwith minimal product contact. Where water quality is unknown or cannot becontrolled, growers may want to consider irrigation practices that minimizecontact between water and the edible portion of the crop (FDA, 1998).

Visual II.1-13

The closer to harvest irrigation occurs, the greater the chance for survival of pathogens and for the presence of residual chemicals on the produce. Irrigationmethods, like drip system, where the contact between water and plant isminimized, are generally less likely to lead to fresh produce contamination,however, the use of good quality water is still important. Sprinklers offer a greater

Hazards associated with irrigation practices are influenced by:• Water source and quality• Amount of water applied• Irrigation program• Irrigation method - degree of contact with the edible portion of the fruit or

vegetable• Soil drainage properties•

Time to harvest date


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degree of contact between the edible portion of the fruit or vegetable and thewater. Therefore, a greater risk of produce contamination may occur. With thesesystems, the use of good quality water and the proper use and maintenance of the equipment is especially important.

Visual II.1-14

Water used for the application of pesticides and foliar fertilizers can be a sourceof microbial contamination. For this reason, the microbiological quality of thewater used for these activities should be considered.

In addition to biological hazards, water also can contain chemical contaminants.When chemigation systems are not properly designed, they can result in seriousground water contamination, increasing the risk of chemical contamination of fresh produce. Safety equipment is available that can prevent back-flow andsubsequent groundwater contamination (Olexa, 1991). This equipment isrelatively inexpensive and can prevent serious hazards.

Additional safeguards against contamination during chemigation include trainingand certification of applicators and water analysis at the source and at locationsnear the water source. In addition, it is important to identify the runoff direction, if runoff takes place. In the case of fertilizers, it important to know the plant toxicity

of the specific fertilizer and to pay close attention to calculated andrecommended dosage rates and schedules of application (Olexa, 1991).

Agricu ltural Water Microb iological Testing Procedures

Visual II.1-15

Microbiological determinations are time consuming so are used to track safetytrends, not for daily monitoring activities. They are generally used to verify thatthe appropriate preventive measures are in place. Microbiological analyses aregenerally performed as indicators of contamination, especially for the verification

Chemigation

Refers to the application of fertilizer or pesticides through irrigation systems.

• Microbiological testing is used to track safety, not for daily monitoringactivities.

• It is important to document the frequency and results of each water test for comparison purposes. Changes may help identify problems.

• These records would become very important in the event of a microbiologicaloutbreak investigation.


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of cleaning programs for tanks, wells, or when contamination from a specificsource or event is suspected.

Proper records of water microbiological quality are an important good agriculturalpractice. It is important to document the frequency and results of each water test

since changes in results may identify problems.

Testing for specific pathogenic bacteria in water may be inappropriate. Theycould be present in very small amounts and thus not detected. Furthermore,microbiological characteristics of water can vary considerably depending on suchfactors as the water source, season, and sampling time. Since waterbornedisease is usually the result of fecal contamination of water supplies, it is moreefficient to determine if fecal contamination is present than to actually look for thepresence of pathogens.

The fecal indicator bacteria are used to identify when fecal contamination of

water has occurred. The fecal indicator bacteria are natural inhabitants of thegastrointestinal tracts of humans and other warm-blooded animals. Thesebacteria are released into the environment with feces and, in general, cause noharm. However, relatively high numbers of fecal indicator bacteria in theenvironment, suggest an increased likelihood of pathogens being present aswell. In the United States, coliform bacteria serve as the indicator organisms for fecal contamination.

Visual II.1-16

To test if the water being used in agricultural production is contaminated withfecal material, the recommended laboratory tests should look for the presence of fecal coliform bacteria, specifically E. coli.

Visual II.1-17

Laboratory assays commonly performed to determine the quality of water for

agricultural usage include:

• Total and fecal coliform bacteria• Enumeration of Escherichia coli

MCL (Maximum contaminant level) for total coliforms in drinking water is Zero

An MCL does not exist for agricultural water, however growers are urged tominimize all hazards over which they have control.


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The maximum contaminant level (MCL) for drinking water for total coliform/E.coliis zero (U.S. EPA, 2001b). An MCL does not exist for agricultural water, however growers are urged to take a proactive part in minimizing sources of microbialcontamination over which they have control. If wells or water sources arecontaminated with these organisms, possible alleviation measures include

disinfecting with chlorine or another disinfectant or filtration of the water source.Part III in the Additional Resources section gives general procedures for disinfecting contaminated wells.

Visual II.1-18

The type of water source will determine the recommended frequency of testing(CSC, 1998). With closed, covered, or underground systems, wherecontamination is less likely to occur, annual testing is sufficient if the well isproperly developed. With open systems, like uncovered wells, open canals and

ponds, testing every three months is recommended to track the water’s safety. Additional testing should be considered after a significant event that might causewater contamination such as heavy rain or flooding.

Visual II.1-19

Source Possible Water Testing FrequencyClosed system, under theground or covered tank

One annual test at the beginning of season

Uncovered well, opencanal, water reservoir,

collection pond

Every three months during the season

Municipal/District water system

Keep records from the municipality/district water system (monthly, quarterly or annual report)

Water Sample Collection• Sterile sample containers should be obtained from the testing laboratory

because containers may be specially prepared for a specific contaminant.• Sampling and handling procedures will depend on the specific water quality

concern and should be followed carefully.• If water has been chlorinated, the presence of residual chlorine or other halogens can prevent the continuation of bacterial action. To prevent this

occurrence, sodium thiosulfate should be added to the collection tube.• If the water is collected from a tap, the water should be allowed to flow for 1-3

minutes before the sample is taken.• The sample should be analyzed as soon as possible and no more than 30 hrs

after its collection.• Samples should be kept cool (


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When testing water, care should be taken in collecting and handling the sampleto assure the integrity of the sample, to avoid contamination during the samplingprocess and to assure changes do not take place in the sample after it iscollected. Some water conditions and/or treatments can affect tests for

microorganisms so samples must receive special treatment if these conditionsexist. For example, if water has been chlorinated, the presence of residualchlorine or other halogens can prevent the continuation of bacterial action. Toprevent this occurrence, sodium thiosulfate should be added to the collectiontube. Basic considerations for the collection of water samples (U.S. EPA, 2000)are described in the visual above, however, precise procedures should beobtained from the testing laboratory being used to assure appropriate samples.

Summary

1. Agricultural land and land that has been used for activities other thanagriculture can be contaminated with pathogenic organisms or toxic chemicalsubstances.

2. As part of a Good Agricultural Practice (GAP) program it is necessary toidentify possible sources of microbial and chemical contamination associatedwith the prior use of land that it is being used for agricultural production. Useof adjacent land is also important and should be investigated.

3. Every time water comes in direct contact with fruits or vegetables, thepossibility of contaminating the produce with pathogens exists. This includeswater used for produce production activities like irrigation and chemicalapplication, fresh produce washing, in packaging facilities and duringtransportation. The quality of water used to produce ice for cooling and other produce handling operations is also important since this can be a source of contamination.

4. The severity of the hazard resulting from poor quality water will depend on thedegree of contact between the water and the produce, the type and amount of microorganisms in the water and their capacity to survive on the produce.

5. Water destined for agricultural production can easily get contaminated withhuman and/or animal feces. It is important to keep animals and children out of the fields and to provide field workers with properly constructed andmaintained restrooms or mobile sanitary units.

6. The maximum contaminant level (MCL) for drinking water for totalcoliform/E.coli is zero. If wells or water sources are contaminated with theseorganisms, possible alleviation measures include disinfecting with chlorine or another disinfectant or filtration of the water source.


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Module 2Organic and Inorganic Fertilizers

Learning Outcomes

Ø Participants should be able to identify potential produce contaminationassociated with the use of organic and inorganic fertilizers.

Ø Participants should be aware of recommended com

Maryland Manual

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