Chlorine and Food Safety White Paper

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Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Impacts of Foodborne Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Trends in Foodborne Disease Outbreak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Chlorination Protects Public Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

The Micro-Culprits of Foodborne Illness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Studies Indicate Contaminated Foods May Cause More Than Gastrointestinal Illness . . . . . . . .9

Human Infection with Foodborne Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Combating Foodborne Disease with Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Chlorine in Food Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

On the Farm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

In Food Processing Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Meat and Poultry Industries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Dairy Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Egg Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Fish and Seafood Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Fresh Produce Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Chlorine in Food Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Chlorine in Food Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Foodborne Disease Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Table of

Contents

1

“…illness due to contaminated food is perhaps the most widespread health problem in the contemporary world and an important cause of reduced economic productivity.”

—Expert Committee on Food Safety convened by the World Health Organization and the Food andAgriculture Organization of the United Nations, 1983

This paper explores the role chlorine plays inthe efforts of industry, public health officials

and consumers to maintain the safety of theglobal food supply. Chlorine and chlorine-containing compounds are critical factors in foodsafety all along the path leading from the farm tothe consumer’s plate.

Preface

2

3

Executive

Chlorine plays a vital role in the safeproduction, processing, transport and

preparation of foods of all varieties. “To date, noother sanitizing agent has appeared whichcompetes with chlorine in all the areas needed forsafe food production” (McLaren, 2000). On thefarm, chlorinated water is used for irrigation andlivestock watering to lower the risk ofcontamination of crops and livestock. Chlorinesolutions are used industrially to wash and sortfruits and vegetables. The dairy, poultry, egg andmeat industries use the chemical in numerousways to prevent contamination that could lead tofoodborne illness. Chlorine is used extensively infood processing and transport to disinfect surfacesof all types (e.g., work surfaces, instruments,machinery, containers) that contact edibleproducts. In the effort to increasefood safety, researchers continueto find innovative uses forchlorine as food travels from “thefarm to the fork.”

The challenges of safe foodproduction and delivery in the21st century are unique in humanhistory. Opportunities for foodcontamination are many. Some ofthese opportunities arise fromhuman negligence or ignorance of hygiene. Inother cases they are a consequence of modernagricultural practices, food handling techniques,changing patterns of food distribution orchanging consumer preferences anddemographics.

In this era of global trade, paths from the farm tothe fork have lengthened. Modern consumersdemand year-round fresh fruits and vegetables of a

wide variety, with fewer preservatives (Zink,1997). This demand fuels the importation ofproduce from countries with variable food safetystandards. It is true that, “in a globalized world,we all swim in a single microbial sea”(Brundtland, 2001).

As a result of changing demographics (e.g., theaging “Baby Boomers”) and better health care, theelderly population is growing. Advances inmedicine are also prolonging the lives of theimmunocompromised. These populations arestatistically more vulnerable to foodborne illness.

In addition, increasing numbersof US residents eat restaurant-prepared foods, renderingthemselves dependent on thefood handling and preparationprocedures followed by theseestablishments.

The US Food and DrugAdministration recentlyannounced a program designedto establish a national baselineon the occurrence of foodborne

disease risk factors within the retail segment of thefood industry. Risk factors outlined are: food fromunsafe sources; inadequate cooking; improperholding temperature; contaminated equipmentand poor personal hygiene (US FDA, 2000).Combating foodborne diseases requires theconstant vigilance of many segments of societyand their awareness of the changing nature of thechallenge. In response to recent concerns about

Summary

Foodborne

illnesses affect

millions in the

United States

annually.

4

potential terrorist threats, US officials are callingfor a stronger public health infrastructure torespond effectively to public health emergencies ofall types, including those related to contaminationof the food supply. This effort may provide betterlinks among local, state, regional and nationalpublic health offices, and improve notificationand response regarding foodborne diseaseoutbreaks.

Although the US food supply is among the safestin the world, foodborne illnesses affect millions inthe United States annually, causing thousands todie. Accompanying the many conveniences ofmodern life is an unfortunate sense ofcomplacency about food safety on the part ofmany consumers. Opportunities for foodcontamination and cross-contamination aboundin home kitchens when consumers fail to practicesafe food preparation and handling.

In the developing world, foodborne disease is amajor cause of infant and childhood mortality.According to the World Health Organization,children under the age of five suffer approximately1.5 billion cases of diarrhea annually, resulting inover 3 million deaths (WHO, 1997). Asignificant proportion of diarrheal diseases are offoodborne origin. (Untreated or inadequatelydisinfected drinking water also accounts for alarge proportion of diarrheal diseases.) Two tothree percent of non-fatal foodborne diseases indeveloping countries result in long-term healthconsequences. The economic costs of foodbornediseases are huge and include treatment and case

investigation costs, work absence and lost humanpotential. Chlorine is a highly effective yetinexpensive weapon available to controlfoodborne disease all over the world.

There are common foodborne pathogens, but thefoodborne “enemy” is not static. Microorganismsharbored in foods evolve and new ones emerge.These may spread rapidly over great distances byfood transportation mechanisms. Surveillance offoodborne pathogens by government and publichealth monitoring of outbreaks, once a relativelysimple task, is now highly complex as peopletravel widely and food is shipped globally.Nevertheless, new technologies afford sensitivetracking techniques and rapid global electronicreporting.

5

Impacts of Foodborne DiseaseThe US food supply is among the safest in theworld. The overall high quality of life enjoyed byAmericans can be attributed, in part, to anabundant, nutritious and relatively risk-free foodsupply. Nevertheless, every year an estimated 76million people in the United States become sick,300,000 are hospitalized and approximately 5,000die as a result of the basic human activity of eating(US Centers for Disease Control, 2001a). Theannual economic cost of foodborne diseases to theUS economy is estimated to be several billiondollars (Satcher, 1996).

Ingestion of foods contaminated with bacteria,viruses and parasites is a major world publichealth issue, especially in developing countries.Particularly susceptible are infants, youngchildren, the elderly, pregnant women andimmunocompromised individuals. According tothe World Health Organization (WHO),foodborne diarrhea is one of the most commonillnesses of children and one of the major causesof infant and childhood mortality in developingcountries. The WHO estimates that children agefive and younger suffer 1.5 billion episodes ofdiarrhea annually from consumption of bothunsanitary drinking water and tainted foods,resulting in over 3 million premature deaths.Repeated childhood bouts of diarrhea have direlong-term consequences including malnutrition,increased vulnerability to many diseases andstunted physical and mental development. TheWHO estimates that approximately 2–3% ofcases of foodborne disease outbreak lead to long-term ill health (WHO, 1999).

Economically, foodborne diseases exact a hugeprice in treatment, case investigation, work

absence and lost human potential due to long-term damaging effects (WHO, 1999). Further,developing nations, which experience the highestrates of foodborne disease, can least afford toaddress the problem effectively. Although thesafety of the US food supply is generally not asubject of concern, complacency is a dangerousattitude. Combating foodborne diseases requiresthe constant vigilance of many segments of societyand their awareness of the changing nature of thechallenge.

Safe practices are critical at every stage of foodproduction and handling, all along the pathleading to, and including, the consumer’s kitchen.Opportunities for food contamination and cross-contamination abound in home kitchens.Consumer awareness of safe food preparation andstorage practices helps guard against foodborneillness originating in the home.

Trends in Foodborne DiseaseOutbreakThe majority of foodborne illness cases arise fromthe consumption of foods of animal origin. Foodstraditionally implicated in outbreaks includeundercooked meat and poultry, seafood andunpasteurized milk. More recently, scientists havediscovered pathogens in foods once believedincapable of supporting their growth. Such foodsinclude eggs, juices, tomatoes, apple cider andlettuce (Prier and Solnick, 2000). While scientistsand health experts work to understand, preventand combat food contamination, their efforts

Introduction

have not kept pace with certain moderndevelopments that exacerbate the health problem.Foodborne illness originating from eatingcontaminated fruits and vegetables, alreadyprevalent in developing countries, is becomingincreasingly common in developed countries(WHO, 1998). There are several possible reasonsfor this. The increasing globalization of food trademeans that contaminated fruits and vegetablesmay be widely distributed. The susceptibility offoods to infection increases with lengtheningtransit times.

Further, as the elderly population increases, theaverage resistance to foodborne disease decreases,resulting in a greater portion of the populationsuccumbing to illness from tainted foods. Notonly is the elderly population increasing, but also,by virtue of rapidly paced medical advances, manymore immunocompromised individuals aresurviving. These include people with chronicrheumatological disease, cancer, solid-organtransplantation and AIDS (WHO, 1998). Suchindividuals’ compromised immune systems makethem more vulnerable to foodborne illness.

Changes in eating habits also may contribute toincreasing numbers of cases of foodborne illnessstemming from contaminated produce. Many areheeding the advice of health experts to increasetheir consumption of fresh fruits and vegetables.The modern consumer demands a wide variety ofthese products year-round, and with fewerpreservatives (Zink, 1997). This demand fuels theimportation of produce from countries with

variable food safety standards. It is believed thatthe number of foreign food items sold in the USincreased by 50%, from 2.7 million items in 1997to 4.1 million in 2000 (Winter, 2001). Finally,according to Collins (1997), the typical Americanover the age of eight is eating four restaurantmeals every week. Increased consumption ofrestaurant-prepared meals increases the potentialfor sickness resulting from improper foodhandling in restaurant kitchens.

Chlorination Protects PublicHealthHistorically, chlorine is one of mankind’s mosttrusted weapons in the war against infectiouswaterborne diseases. Drinking water chlorination,first introduced in Great Britain in the early1900’s and shortly afterwards in the US,immediately improved the quality of life whereverit was employed. Chlorination and filtration ofraw water are responsible for the virtualelimination of serious waterborne diseases such ascholera, typhoid, dysentery and hepatitis A(White, 1986). LIFE magazine, in rating the 100most important historical events of the pastmillennium, called drinking water chlorinationand filtration “…probably the most significantpublic health advance of the millennium”(Anonymous, 1997).

While chlorine’s role in protecting againstwaterborne disease is widely recognized, chlorinealso plays a vital role in the safe production of awide variety of foods.

6

7

Bacteria and viruses are the most commoncauses of foodborne illacness; protozoa may

also cause sickness. Among bacteria,Campylobacter, Salmonella, E. coli 0157:H7 andVibrio cause the majority of foodborne sicknesscases. The Norwalk viruses (also known ascaliciviruses), are common culprits in foodborneillness, but are rarely diagnosed due to theunavailability of the diagnostic laboratory test.

Hepatitis A is a virus that infects the liver andcauses the disease hepatitis A. Toxoplasma gondiiand Cryptosporidium parvum are commonparasitic protozoa that cause foodborne illness.Table 1 lists pertinent information on each ofthese common microorganisms.

Foodborne IllnessThe Micro-Culprits of

Table 1: Common Foodborne Pathogens1

Pathogen Infection Symptoms in Humans Pathogen Reservoir Cause of Infection

Bacteria

Campylobacter Fever, diarrhea, abdominal Intestines of healthy Eating undercookedcramps, nausea, vomiting; birds; Raw poultry chicken or foodsMost commonly identified cause meat, cattle and contaminated with juicesof diarrheal illness in the world; sometimes swine. from undercooked May cause Guillain-Barre chicken;syndrome. In developing countries:

unchlorinated drinkingwater supplies, e.g.,wells, contaminatedwith poultry feces.

Salmonella Fever, diarrhea, abdominal Intestines of birds, Spread to humans by acramps, headache. reptiles and mammals. variety of foods of

animal origin, e.g., undercooked poultry,contaminated eggs (eaten raw) and raw milk;May invade thebloodstream in personsof poor health orweakened immunesystems, causing life-threatening infections.

8

1 Adapted from US CDC (2001b), US FDA on-line “Bad Bug Book” (as viewed 8-16-01), and personal communication with Dr. Fred Reiff (10-4-01).

Table 1: Common Foodborne Pathogens1 (Continued)

Pathogen Infection Symptoms in Humans Pathogen Reservoir Cause of Infection

E. coli O157:H7 Severe, bloody diarrhea, painful Cattle and similar Consuming food or abdominal cramps; not much animals; also resides in water that has beenfever; humans. contaminated withMay cause acute kidney failure, microscopic amounts ofhemolytic uremic syndrome, cow feces;in children. Contaminated raw milk.

Vibrio Watery diarrhea, abdominal pain. Estuarine and marine Consuming raw,parahaemolyticus environment and fish improperly cooked, or

and seafood from cooked, recontaminatedthose environments. fish and shellfish.

Viruses

Norwalk-like Acute gastrointestinal illness, Infected persons for up Contact with infectedvirus usually with more vomiting to 2 days after diarrhea persons/food handlers.

than diarrhea; stops.Headache, myalgia and low-grade fever.

Hepatitis A Infects the liver and causes Feces of infected people; Person-to-personhepatitis A virus: fever, malaise, Poor sanitation and fecal-oral route bynausea, abdominal discomfort, crowding facilitate infected food handlers.dark urine and jaundice. transmission.

Protozoa

Toxoplasma No symptoms but possible Found in virtually all Consuming raw or gondii diarrhea; animal foods. undercooked meat or

Infected pregnant women may contact with cats that pass the disease to their fetuses, shed cysts in their fecesresulting in death of the fetus or during acute infection.severe health effects, such as mental retardation.

Cryptosporidium Profuse watery diarrhea; Waterborne or foundparvum Life-threatening among the in animal manures.

immunocompromised.

work surfaces and utensils. Fabrics and spongesused to wipe surfaces also may transfer pathogens.Cross-contamination is the “…transfer of harmfulsubstances or disease-causing microorganisms tofood by hands, food-contact surfaces, sponges,cloth towels and utensils that touch raw food, arenot cleaned, and then touch ready-to-eat foods.Cross-contamination can also occur when rawfood touches or drips onto cooked or ready-to-eatfoods” (Partnership for Food Safety EducationOn-Line Glossary).

Studies Indicate ContaminatedFoods May Cause More ThanGastrointestinal IllnessBesides the expected gastrointestinal upset, otherchronic diseases may result from foodborneinfections. The US Centers for Disease Controland Prevention (CDC) (2001a) reports that in thepast fifteen years, several important diseases ofpreviously unknown cause have been determinedto be complications of foodborne infections.Examples are Guillain-Barre syndrome, which canbe caused by Camplyobacter infection, andhemolytic uremic syndrome (acute kidney failurein children), caused by E. coli O157:H7. Inaddition, Salmonella infection may producereactive arthritis and serious infections, whileListeria can cause meningitis and stillbirths. In thefuture, further associations between diseases andfood contamination may be uncovered.

Human Infection with FoodbornePathogensHow are harmful microorganisms transmitted topeople? Healthy animals raised for food host avariety of microbes, especially in their intestines.These microbes can transfer to meat and poultryduring animal slaughter. Fruits and vegetablesmay be contaminated if they are irrigated orwashed with waters contaminated with animalmanure or human sewage. Filter feeding shellfishconcentrate bacteria, such as Vibrio, that arenaturally present in sea water, or other microbesoriginating in human sewage disposed of inmarine waters. During food processing, infectedhuman food handlers may contaminate foods byintroducing microbes by hand contact.Alternatively, food may be contaminated bycontact with contaminated surfaces, including

9

10

Chlorine is a highly effective yet inexpensiveweapon used in the battle to control

foodborne disease. Chlorine generally is applied tocontaminated surfaces in the form of elementalchlorine (chlorine gas) or a bleach solution madefrom either liquid sodium hypochlorite orgranular calcium hypochlorite. These three formsof chlorine have been approved for use by the USEnvironmental Protection Agency and byindividual states. General statements aboutchlorine in this document refer to these threecommonly used chemical forms. The inhibitoryor lethal activity depends on the amount of freeavailable chlorine in the solution (in the form ofhypochlorous acid, HOCl, present in bleach andchlorine solutions) that comes in contact withmicrobial cells. Free chlorine disinfects bychemically disrupting bacterial cell walls andmembranes through oxidation of a chemicalgroup known as the thiol group (WHO, 1998).Many viruses and protozoa are also inactivated bychlorine. Thus, chlorine is a powerful weaponused to inactivate harmful microorganisms andhelp prevent the spread of disease.

To minimize chlorine waste and optimize itsefficient use, chlorine concentrations in sanitizingsolutions should be monitored. The concentrationof the fast-acting, antimicrobial hypochlorousacid, the chemical species providing free availablechlorine to disinfectant solutions, is a function ofpH. Between pH 6.5 and 7.0, HOCl exists as 95-80% of the free chlorine concentration. At pHgreater than 8, the free chlorine concentration is

less than 20%. To complicate matters, the papertest strips and colorimetric kits used to monitorchlorine do not distinguish between the presenceof HOCl and a far less active chemical species,hypochlorite (OCl-). Therefore, to maintain agiven free chlorine concentration, it is necessary tomonitor and adjust the pH of disinfectantsolutions (Suslow, 2000). Efficient use of chlorinefor various food industry disinfection purposescan reduce costs (especially by minimizingmachinery and equipment corrosion) and thenegative environmental impact of wastingchlorine (Denny, 2000).

Combating Foodborne Disease with Chlorine

11

On the FarmIn the production of safe, nutritious foods,chlorine’s first role is on the farm. Chlorinatedwater, used for irrigation and livestock watering,lowers the risk of waterborne contamination tocrops and farm animals. Chlorine also preventsthe formation of bacterial slime and biofilms onirrigation equipment used to deliver water tocrops (Suslow, 2000).

Recently, scientists at the Agricultural ResearchService in College Station, Texas, reported thatthe chlorine-containing compound sodiumchlorate, fed in low doses to cows and pigs priorto slaughter, selectively kills Salmonellatyphimurium and Escherichia coli 0157:H7. TheCDC estimates about 1.4 million cases ofsalmonellosis and 73,000 cases ofdiarrheal illness are caused bythese two pathogens annually(USDA, 2001).

Routine seed disinfection isachieved by soaking seeds inchlorinated water, often withheating, to reduce the potentialfor viral, bacterial and fungaldisease epidemics (Suslow, 2000).Recent outbreaks of E. coli andSalmonella in raw alfalfa and clover sprouts in theUS and Japan prompted a review of industrypractices by the US Food and DrugAdministration and the California Department ofHealth Services. A series of safety measures wereintroduced in the US in 1999, including treatingsprout seeds with chlorine dilutions and regulartesting of irrigation water. Sprouts, consideredready-to-eat foods, are finished in warm, wet, darkconditions that are ideal for microbial growth

Chlorine in

Food Production

(Green, 2001). Researchers have found thatpresoaking contaminated sprout seeds in a 20,000mg/liter calcium hypochlorite solution reducesthe risk of infection (Brooks et al., 2001).

Chlorine is an effective, inexpensive agent used tohelp manage post-harvest diseases affecting fruitand vegetable crops. Many fruits and vegetablesare treated in flumes, water dump tanks, spraywashers or hydrocoolers to which chlorine isadded (Suslow, 2000). Up to 30% of harvestedcrops, especially highly perishable items such astomatoes, squash and peaches, may be lost to

post-harvest disease, according tothe North Carolina CooperativeExtension Service. Investmentsmade to save harvested crops areusually less costly and lessenvironmentally damaging thanefforts to increase production.Currently, chlorination is one ofthe few chemical optionsavailable to combat post-harvestdisease. Various fungicides andbactericides that had been used

alone or in combination with chlorine in the pasthave been removed from the market due toeconomic, environmental or health concerns.

Effective chlorination of harvested crops dependsupon frequent monitoring of the chlorinesolution and an understanding of the variousfactors involved. According to the North CarolinaExtension Service, these factors include the pH ofthe solution, chlorine concentration, water

Up to 30% of

harvested crops

may be lost to

post-harvest

disease.

12

temperature, amount of organic matter present,exposure time and the growth stage of thepathogens present.

In Food Processing FacilitiesThe usefulness of chlorine is abundantly evidentin food processing facilities where it is usedextensively to prevent food contamination. Foodprocessing facilities rely heavily on chlorine todisinfect various food and food-contact surfaces.Chlorine also is used frequently as a whiteningagent to remove stains on equipment andwalkways.

Chlorine quickly kills microorganisms on foodsurfaces, producing a lethal effect in the first fewseconds of treatment. Unlike the chlorination of aliquid medium, such as raw water in whichchlorine is effectively and uniformly dispersed,chlorine disinfection of solid surfaces generallypresents a more difficult challenge. Physical andchemical characteristics of surfaces involved infood production vary greatly. Food surfacesthemselves vary in geometric area, texture, pHand temperature. These surface propertiesinfluence the efficiency of chlorine disinfection.For example, the convoluted surface of acantaloupe harbors microorganisms moreefficiently than the smooth surface of awatermelon. (In June, 2001, in fact, there weretwo deaths and many cases of food poisoningacross 14 US states attributed to Salmonella-infected cantaloupes grown in Mexico. Salmonellaare believed to be transferred from the infected

cantaloupe rind to the interior fruit via cuttingknives.) Similarly, food-processing machinery withnumerous interconnecting parts of various shapes,sizes and materials can be extremely difficult todecontaminate. Even a stainless steel table surfacemay present a disinfection challenge, given theability of bacteria to colonize microscopic crevices(see photomicrograph below).

Photomicrograph of L. monocytogenes bacteria colonizing crevice instainless steel food preparation surface. ©Amy C. Lee Wong, Food Research Institute, University ofWisconsin, Madison, author, licensed for use, ASM MicrobeLibrary(http://www.microbelibrary.org).

The relative temperatures of food tissue anddisinfectant help determine the effectiveness ofdisinfection. The temperature of wash watershould be at least 10ºC higher than that of thefruits or vegetables to achieve a positivetemperature differential, and to minimize theuptake of wash water through stem tissues oropen areas in skin or leaves (Bartz and Showalter,1981; Zhuang et al., 1995).

In addition to the consideration of surfaceproperties and temperature, the particularvarieties of microorganism(s) infecting the hostsurface help determine the effectiveness ofdisinfection. It is known, for example, that amongbacteria, Salmonella, Escherichia coli and Shigellaare less resistant than Listeria monocytogenes.

Researchers have developed a method to allowresidual chlorine to remain in water after it is usedto wash foods. The residual chlorine is an addedmeasure of disinfection protection. The methodhas become known as “in-plant chlorination”(Griffin, 1946). Fruits, vegetables, poultryproducts, eggs, fish, frog legs and nut meats arewashed with chlorinated water prior to being soldto the public or undergoing additional processing.In addition, flours are bleached with chlorine. Theadvantages of in-plant chlorination include odorand slime reduction, reduced clean-up time, lowerbacterial counts on finished products and noapparent corrosion of metal equipment withcontinuous contact (Ritchell, 1947).

Meat and Poultry IndustriesChlorine solutions areused in many facets ofmeat and poultryprocessing, includingworker hand, foot, shoeand boot sanitizing;equipment cleaning,

sanitizing and whitening; and meat and poultrydisinfection. Birds in poultry slaughteringfacilities are cooled in chillers to which a chemicaldisinfectant, usually chlorine, is added. Chlorinein the chiller water reduces microbial content ofthe poultry and prevents cross-contamination.Beef carcasses, on the other hand, are washed withplain tap water as the organic material associatedwith beef quickly deactivates chlorine (Brashears,2000).

Dairy IndustryThe dairy industry wasthe first of the foodindustries to exploit thegermicidal and deodorantproperties of chlorine.Cheese plants are thelargest users of chlorine in

the dairy industry (Vavak, 2000). The Grade “A”Pasteurized Milk Ordinance (US FDA, 1995),issued by the US Department of Health andHuman Services, specifies the officially approvedmethods of sanitation for dairy plants. Chlorinecompounds used for dairy sanitation includecalcium and sodium hypochlorite and certainorganic chlorine compounds.

13

14

Egg IndustryChlorine, combined withanionic detergents,effectively removesprotein residues, and to alesser extent, carbohydrateresidues from egg shellsurfaces. The chemical

also reduces bacteria levels on egg shells. Due tothe high pH and organic load of egg wash water,chlorine serves more as a cleaning compound thana sanitizer in these solutions (McKee, 2000).

Fish and Seafood Industry

Chlorine, in the form ofsodium and calciumhypochlorite, is used inseafood processingsanitation applications.Scientists have found thatthe human pathogen

Aeromonas hydrophila, commonly isolated fromseafoods, forms biofilms on stainless steel within athree-minute contact time (Bal’a et al.,1999).Furthermore, they found the complexity ofbiofilms to increase with time at roomtemperature. Chlorine applied to infected stainlesssteel inactivates the biofilms. The effectiveness ofchlorine on such biofilms is greatest when it isapplied soon after infection.

Fresh Produce IndustryChlorine is usedextensively as adisinfectant in wash, sprayand flume waters in theraw fruit and vegetableindustry (WHO, 1998).The three forms of

agricultural chlorine commonly used for freshfruits and vegetables are chlorine gas, calciumhypochlorite and sodium hypochlorite.

Chlorine gas is generally restricted to use in verylarge operations and requires automatedcontrolled injections systems with in-line pHmonitoring. It is highly effective in situations inwhich soil, plant debris and decaying fruit orvegetables may enter early stages of washing andgrading. Calcium hypochlorite, available as agranulated powder or compressed tablet, is themost common source of chlorine used fordisinfection of produce and produce processwater. Sodium hypochlorite, a water-basedformulation, is the chlorine source frequently usedin small-scale operations (Suslow, 2000).

An increasingly popular broad-spectrumantimicrobial agent used on foods, especially freshproduce, is chlorine dioxide. Chlorine dioxide isefficacious against bacteria on a variety ofvegetables and fruits including carrots,mushrooms, asparagus, tomatoes, lettuce,cabbage, cherries, strawberries and apples.Reducing bacterial concentrations on produceincreases the shelf lives of these foods. Chlorinedioxide also controls the fungal disease known aslate blight and other secondary infections such assoft rot on stored potatoes (Khanna, 2002).

As foods are transported ever greater distancesfor processing and distribution, the potential

for food contamination rises. Chlorine is used tolower the risk of food contamination duringtransport.

Chlorine sanitization of storage containersprevents food contamination during transport. Tooptimize chlorine use efficiency, field bins, foodtotes, cartons and pallets should be sanitized afterpre-washing to remove soils and organic debris asthese materials quickly deplete free availablechlorine (Suslow, 2000). Beyond its disinfectionbenefits, calcium hypochlorite is reported toimprove the shelf life and disease resistance ofproduce by adding calcium to the cell walls offruits and vegetables (Suslow, 2000).

Unsanitary ice used to chill produce duringtransportation can transmit diseases to producethat may cause decay of the produce or illness tothe consumer. Ice made from potable, chlorinatedwater is an effective safeguard against externalcontamination during transport (Suslow, 2000).

15

Chlorine in

Food Transportation

16

Chlorine in

Food Preparation

2 A recent study by US Department of Agriculture food microbiologist D. Ukuku suggests that washing cantaloupes with diluted chlorine orhydrogen peroxide solutions may protect against Salmonella contamination (Beaudin, 2001). (The fruit exterior should be thoroughly rinsed withwater after washing and before cutting.) The Salmonella, living on the convoluted rind, contaminate cantaloupe interior fruit via cutting knives.Cantaloupe is a particularly difficult fruit to decontaminate due to its irregular exterior surface, with numerous crevices harboring soil and

Chlorine plays an essential role in the finaldestination of many fresh foods: restaurant andconsumer kitchens. Infectious germs can spreadquickly when food is not prepared and storedsafely, causing foodborne illness. As consumerscarry out the final stages of food preparation,dilute solutions of chlorine bleach (1-3tablespoons household chlorine bleach in onegallon of water) are recommended for use insanitizing cutting boards, countertops andcooking surfaces. (Separate cutting boards arerecommended for meat and produce.) Cloths andsponges, which contact raw foods, should besoaked frequently in a stronger disinfectingsolution of 3/4 cup bleach in one gallon of water.Washing raw foods with chlorine solutions is notgenerally advised2.

In a comparison study of commercial andhomemade disinfectants, scientists found thatcommercial products, such as chlorine-basedhousehold sanitizers, kill more than 99.9% ofbacteria, including E. coli and Salmonella, whilenatural products such as vinegar and baking sodawere not nearly as effective (Rutala et al., 2000).In addition, as opposed to antibacterial sanitizingproducts that attack only bacteria, chlorineproducts kill both bacteria and viruses, both ofwhich can sicken people.

Experts estimate that washing hands often andthoroughly could eliminate nearly half the cases offoodborne illness. Futhermore, hot foods shouldbe kept hot (at temperatures greater than 140ºF)and cold foods cold (at temperatures less than40ºF). Microorganisms thrive in the range 40-140ºF, and toxins produced in that range may notbe destroyed by reheating foods. Foods should bethawed in the refrigerator or microwave oven, orin a sealed package in cold water that is changedevery half hour. Only pasteurized eggs should beused in recipes requiring uncooked eggs (Brody,2001). Food should be stored in clean, covered

17

1. WASH

WASH dishes, utensils, cookware, cutting boards, appliances and cooking surfaces with HOT, SOAPYWATER to remove visible soil. 2. RINSE

Thoroughly RINSE OFF soap and film.

containers. Consumers who heed food safetyadvice significantly increase their defenses againstfoodborne diseases.

Restaurant kitchens typically use sodiumhypochlorite solutions to disinfect kitchen worksurfaces and equipment. The Chlorine ChemistryCouncil, in concert with the Water Quality andHealth Council and the National Restaurant

Association, distributes food safety posters torestaurants listing detailed directions for sanitizingporous and nonporous food contact surfaces. Theposters are available in English, Spanish,Cantonese and Mandarin (see below).

Germs that cause foodborne illness can't be seen, which is why sanitarycleaning practices are so important in restaurants.

All Food Contact Surfaces Must Be Washed, Rinsed and Sanitized

18

FOR SURFACES THAT COME IN CONTACT WITH FOOD■ Nonporous Surfaces — Tile, Metal and Hard Plastics

Use 1 tablespoon liquid bleach per gallon of water (200 ppm‡). Leave wet for 2 minutes. Air dry.

■ Porous Surfaces — Wood, Rubber or Soft PlasticsUse 3 tablespoons liquid bleach per gallon ofwater (600 ppm‡). Leave wet for 2 minutes.Rinse and air dry.

WASH, RINSE and SANITIZE pots, pans, glasses, dishes and utensils.

WASH, RINSE and SANITIZE other food contact surfaces.

3. SANITIZE

REGULAR CHLORINE BLEACH* diluted inwater is an easy-to-use germ killer. Hereare two effective bleach and water cleaning solutions:

1 Tablespoon

3 Tablespoons

* Recommendations are for regular chlorine bleach (5.25% sodium hypochlorite);do not use scented or color safe bleaches

‡ parts per million

net.htm), state laboratories and the CDC cancompare strains of E. coli O157:H7 and anincreasing number of other pathogens to detectwidespread outbreaks.

The changing face of the enemy complicates thebattle against foodborne illness. New foodbornepathogens will continue to be identified and rarebut known pathogens may reemerge as publichealth threats. Improved surveillance allows abetter understanding of the impact of theseinfections and how to prevent them. The CDChas enhanced foodborne disease outbreak

investigation by applyingsophisticated epidemiologic andmicrobiologic techniques tofield investigations.Collaborative active surveillancesystems include the CDC’selectronic transmission system,the Public Health LaboratoryInformation System in statehealth departments andautomated reporting andoutbreak detection analysis

(Satcher, 1996). Nevertheless, public healthofficials should continue to improve food safetysurveillance and coordination among variouslevels of government. In response to recentconcerns about potential terrorist threats, USofficials are calling for a stronger public healthinfrastructure to respond effectively to publichealth emergencies of all types, including thoserelated to contamination of the food supply. This

Globalization of the food supply and changinglife styles have complicated greatly the work

of government public health officials in trackingthe sources of foodborne disease outbreaks. In thepast when food distribution networks were smalland easily mapped, outbreaks could be relativelyeasily traced. Food distribution in the US today ismuch more complex. The classic case of acongregation’s food poisoning from undercookedmeat at a church supper would entail considerablyless investigation than would infections ofnumerous widely dispersed individuals who mayhave consumed the same source of tainted foodover a variable period of time. For example, atainted airline meal could be served to some of thepassengers on each of several different flights overa period of 24 hours. Theconsumers of the tainted mealbecome widely dispersed due tothe fact the meal was served onseveral flights. Because of mealselection, not all those who ate in-flight meals become sick.

According to the CDC (2001a),since many sick people do notseek medical attention, and sincemany who do are not tested,numerous cases of foodborneillness go undiagnosed. The CDC estimates that38 cases of salmonellosis occur for every case thatis diagnosed and reported to public healthauthorities. The CDC uses a DNA“fingerprinting” technology to more easily detectfoodborne disease outbreaks across the UnitedStates. Using the new molecular subtypingnetwork, PulseNet(http://www.cdc.gov/ncidod/dbmd/pulsenet/pulse

19

“The way to be

safe is never

to be secure.”

Thomas Fuller,

1608-1661

Foodborne

Disease Surveillance

20

effort may provide better links among local, state,regional and national public health offices, andimprove notification and response regardingfoodborne disease outbreaks. The United NationsFood and Agriculture Organization of the WHOrecently called upon countries to upgrade theirdomestic food safety systems. The organizationnoted that developing countries, with no foodsafety systems in place, have an opportunity to“leap-forward,” and capitalize on the experiencesof industrialized countries, adopting modern foodsafety systems that work well (United NationsFood and Agriculture Organization, 2001).

21

Conclusions

Chlorine is a highly effective, inexpensivechemical disinfectant that is used to help

maintain the safety of the nation’s food supply.Chlorine has extensive critical uses all along thepath from the farm to the fork. Tried and trustedmethods of chlorine disinfection are welldocumented in numerous aspects of the foodproduction industry. Untold numbers of cases offoodborne disease are prevented by chlorinedisinfection of foods and food-contact surfaces.From the farm, to food handling, processing andtransportation facilities, to restaurant andconsumer kitchens, chlorine successfullyinactivates a wide variety of disease-causingmicroorganisms associated with foods.

American Society for Microbiology Microbe Library. [on-line]. Available:http://www.microbelibrary.org/ (as viewed 12-19-01).

Anonymous (1997, Nov. 3). Microorganisms that contaminate food. Scientific American. [on-line].Available: http://www.sciam.com/explorations/110397salmonella/foodtable.html (as viewed 10-3-01).

Anonymous (1997, Fall). The Millenium: The 100 Events Headline: No. 46; Water Purification. LifeMagazine Special Double Issue.

Bal’a, M.F.A, It, J.D. and Marshall, D.L. (1999). Moderate heat or chlorine destroys Aeromonashydrophila biofilms on stainless steel. Dairy, Food, and Environmental Sanitation, 19, pp. 29-34.

Bartz, J.A. and Showalter, R.K. (1981). Infiltration of tomatoes by bacteria in aqueous suspension.Phytopathology, 71, pp. 515-18.

Beaudin, M. (2001, August 23). Wash cantaloupes with chlorine: US. Montreal Gazette.

Brashears, M. (2000). Chlorine usage in meat and poultry processing facilities. In D.A. McLaren (Ed.),Use of chlorine-based sanitizers and disinfectants in the food manufacturing industry: Current andemerging technology approaches on waste minimization—Technology for efficient use of chlorine-basedmaterials. University of Nebraska Food Processing Center.

Brody, J.E. (2001, January 30). Clean cutting boards are not enough: New lessons in food safety. TheNew York Times, Personal Health.

Brooks, J.T., Rowe, S.Y., Shillam, P., Heltzel, D.M., Hunter, S.B., Slutsher, L., Hoekstra, R.M., andLuby, S.P. (2001). Salmonella typhimurium infections transmitted by chlorine-pretreated clover sproutseeds. American Journal of Epidemiology, 154, pp. 1020-28.

Brundtland, G.H. (2001). Address to the Codex Alimentarius Commission meeting, Geneva, July 2-7,2001.

Chlorine Chemistry Council, Water Quality and Health Council, and the National RestaurantAssociation Poster: Good Food Starts with a Clean Kitchen.

Collins, J.E. (1997). Impact of changing consumer lifestyles on the emergence/reemergence of foodbornepathogens. Emerging Infectious Diseases, 3, pp. 471-9.

Denny, C. (2000). Survey of current published literature. In D.A. McLaren (Ed.), Use of chlorine-basedsanitizers and disinfectants in the food manufacturing industry: Current and emerging technologyapproaches on waste minimization—Technology for efficient use of chlorine-based materials. University ofNebraska Food Processing Center.

Green, E. (2001, June 13). Raw sprouts: Health food or health risk 2000. Los Angeles Times.

Griffin, A.A. (1946). Break-point chlorination practices. Technical Publication No. 213, Wallace andTiernan.

22

References

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McKee, S. (2000). Chlorine usage in egg processing facilities. In D.A. McLaren (Ed.), Use of chlorine-based sanitizers and disinfectants in the food manufacturing industry: Current and emerging technologyapproaches on waste minimization—Technology for efficient use of chlorine-based materials. University ofNebraska Food Processing Center.

McLaren, D.A. (2000). Use of chlorine-based sanitizers and disinfectants in the food manufacturingindustry: Current and emerging technology approaches on waste minimization—Technology for efficientuse of chlorine-based materials. University of Nebraska Food Processing Center.

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