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Introduction to toxicology and risk

assessment

Ivonne M.C.M. Rietjens

Ivonne.rietjens@wur.nl

(3) Food Toxicology

Compounds of concern in food toxicology

• additives • indirect additives (from packaging material) • animal drugs • pesticide residues • unavoidable contaminants • natural toxins • novel food ingredients • food supplements • substances from cooking/processing

Compounds of concern in food toxicology

• additives • indirect additives (from packaging material) • animal drugs • pesticide residues • unavoidable contaminants • natural toxins • novel food ingredients • food supplements • substances from cooking/processing

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Non genotoxic ADI = Acceptable daily intake for avoidable contaminants like additives, pesticides

TDI = Tolerable daily intake for unavoidable contaminants like dioxins, mycotoxins, heavy metals

= NOAEL or BMDL x 1/10 x 1/10 x other UFs

interspecies intraspecies quality of data type of exposure

Percentage of samples with measurable residues above the MRL- 2009

97.4% (64,810 samples) of the surveillance samples analysed (national and EU-coordinated multi-annual programme) were below or at the legal MRLs In 2.6% (1,740 samples) of the samples the legal limits were exceeded for one or more pesticides

Pesticide residues in food

Risk assessment pesticide residues

Acute exposure of the European population to carbendazim residues in table grapes, expressed as percent of the ARfD set for carbendazim

Acute exposure of the European population to carbendazim residues in peppers, expressed as percent of the ARfD set for carbendazim.

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Pesticides

EFSA concluded: - long-term exposure of consumers did not raise health concerns - short-term exposure: for 77 food samples analysed the acute reference dose (ARfD) might have been exceeded if the pertinent food was consumed in high amounts

Compounds of concern in food toxicology

• additives • indirect additives (from packaging material) • animal drugs • pesticide residues • nonfunctional/ unavoidable contaminants • natural toxins • novel food ingredients • food supplements • substances from cooking/ processing

Natural toxins

• mycotoxins (from fungi) • phytotoxins (from plants) • phycotoxins (from marine algae) • animal toxins • bacterial toxins

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Mycotoxins: food safety risk in a variety of cereal, fruit, nut and milk-based products

Mycotoxins of present concern 1) from Aspergillus and Penicillium spp aflatoxins (B,G,M), ochratoxin 2) from Fusarium spp trichothecenes, fumonisines

Aspergillus and Penicillium

Mycotoxins of major concern and their adverse effects upon chronic exposure aflatoxins carcinogenicity (liver) sterigmatocystin carcinogenicity (liver) ochratoxin A carcinogenicity (kidney)(BEN) citrinin carcinogenicity (liver, kidney) patulin carcinogenicity (liver, kidney)

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Fusarium

Mycotoxins of major concern and their adverse effects upon chronic exposure: • trichothecenes immunotoxicity growth retardation • fumonisins oesophagal cancer • zearalenone cancer reproductive organs

Aspergillus flavus In nuts, beer, wheat

Example: aflatoxine B1

mutation hotspots P53 tumor suppressor gene liver cancer

International Agency for research on Cancer (IARC) classification Group 1: carcinogenic to man; should be forbidden Group 2A: probably carcinogenic to man; should be forbidden Group 2B: possibly carcinogenic for man Group 3: compound cannot be classified because of lack of sufficient data Group 4: proven to be non-carcinogenic for man

based on scientific arguments and conservative

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Epidemiology aflatoxin: high incidence of liver tumors in India, Thailand, Mozambique, Swaziland, Transkei, Kenya related to aflatoxin exposure

Estimated daily intake US 18 ng AFB1 /person/day 44 ng AFM1/person/day Zimbabwe 1 mg AFB1 /person/day

Relation between aflatoxin and cancer in Kenya (major source: maize ao cereals)

Intake Cancer incidence ng/kg bw/day per 106/year 4.9 31 7.9 108 14.9 121

Epidemiology aflatoxin:

Epidemiology aflatoxin: high incidence of liver tumors in Qidong China related to aflatoxin exposure

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EFSA (2004)

“In consideration of the carcinogenic properties of aflatoxin B1, human exposure should be reduced to levels as low as reasonable achievable” (ALARA) “maximum levels for aflatoxin M1 have been set for consumable milk at 0.05 μg/kg, and 0.025 μg/kg for infant formulae, respectively, aiming to reduce human exposure to the lowest achievable level”

for compounds that are both genotoxic and carcinogenic

MOE = BMDL10

EDI (human)

BMD BMDL

BMR

BMR = benchmark response (pe 10% effect above background) BMD = Bench Mark Dose; dose causing the BMR BMDL = lower confidence limit of the BMD

MOE > 10 000: low concern

Risk assessment: Margin of Exposure (MOE)

EFSA (2007) MOE assessment AFB1

Data on liver tumors in rats: BMDL10 of 0.17 μg/kg bw per day

Estimated daily intake: 0.352-1.934 ng/kg bw per day

MOE: 88-483

“The margins of exposure (MOEs) for all estimated intakes indicated a potential concern for human health.”

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Best approach to reduce aflatoxin exposure worldwide

• prevention based on good agricultural practice • possible decontamination • education of producer and consumer • combined with regulatory limits and monitoring programs

Example vomitoxin = DON = deoxynivalenol

O

O

OH

CH2OH

H

H

OHO

H

trichothecene from Fusarium spp on wheat in bread, and other wheat products

Immunotoxicity, growth retardation

DON: infection wheat

unavoidable - GR: undesired effect = growth retardation TDI: 0.5 mg/kg bw/day (requires MRL 100 mg/kg wheat = detection limit and 59-84 % of NL wheat abbandonned) - JECFA suggested TDI of 1 mg/kg bw/day (growth retardation

Netherlands: 1999 children 1-4 jr 50 % 1.3 mg/kg bw/day 5 % > 2.4 mg/kg bw/day

- GR: adverse effects nausea & immunotoxicity TDI at 2.5 mg/kg bw/day

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Risk assessment DON 26,613 analytical results collected by 21 European countries 2007 - 2012

DON was found in almost half the samples, the highest levels being observed in wheat, maize and oat grains and derived products

chronic exposure between 0.22 and 1.86 μg/kg b.w. per day. main contributor: bread and rolls exposure of consumers close to or above the TDI of 1 μg/kg b.w. per day is possible

Natural toxins

• mycotoxins (from fungi) • phytotoxins (from plants) • phycotoxins (from marine algae) • animal toxins • bacterial toxins

October 2001: Netherlands: 8 people ended up in hospital after drinking star mix tea

Phytotoxins example: Star Anise

Anisatin in Japanese

not Chinese star anise

GABA antagonist

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HCN: Cassave linamarin

Phytotoxins: cyanogenic glycosides

Konzo: tropical myelopathy spastic paralysis

• Belgium (1990s) botanical weight loss preparation • 70-100 patients kidney damage and cancer due to aristolochic acids • Aristolochia fangchi instead of

Stephania tetrandra (fangji) • NL warenwet (2001): ban on aristolochic acids • botanicals: no European regulations / legislations

Instead of

Phytotoxins: aristolochic acids

Phytotoxins

http://www.efsa.europa.eu/en/scdocs/scdoc/1249.htm

http://www.efsa.europa.eu/en/scdocs/scdoc/280r.htm

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“There is world-wide recognition of potential problems associated with botanicals and botanical products, not only in terms of safety, but also in terms of the claimed amounts and stability of the active ingredients.”

“As the market volume expands, so does the need for a better characterisation of botanicals and botanical preparations, and for harmonising the scientific assessment of risks from exposure of consumers to these products”

Phytotoxins: EFSA:

Natural toxins

• mycotoxins (from fungi) • phytotoxins (from plants) • phycotoxins (from marine algae) • animal toxins • bacterial toxins

mostly: dinoflagellata toxins accumulate in food chain (toxic mussels) bloom: red tide or red water

Phycotoxins

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paralytic shellfish poison (PSP)

diarrhetic shellfish poison (DSP)

neurotoxic shellfish poison (NSP)

amnesic shellfish poison (ASP)

ciguatera fish poison (CFP)

alexandrium sp. saxitoxin

dinophysis sp. dinophysis toxin

gymnodinium sp. brevetoxin

Pseudo-nitzschia sp. domoic acid

Gambierdiscus sp. ciguatera toxin

Phycotoxins

Natural toxins

• mycotoxins (from fungi) • phytotoxins (from plants) • phycotoxins (from marine algae) • animal toxins • bacterial toxins

Example: tetrodotoxin

from puffer fish blocks Na+ channels neurons paralysis

Japan: 75 deaths/year

N H

H N

H

H

OH H

H

H

OH

OH

OH

H

O

O

O-

CH2OH

H2N

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Natural toxins

• mycotoxins (from fungi) • phytotoxins (from plants) • phycotoxins (from marine algae) • animal toxins • bacterial toxins

botulism: Clostridium botulinum Type A : contaminated food (man) Type B : contaminated food (man) Type C : deadly for birds Type D : in cattle Type E : in fish, dangerous for man Type F : dangerous for man

Mechanism: botulinum toxin inhibits release of acetylcholine by presynaptic membrane of motor endplate

bacterial toxins (p.e. botulinum toxin)

LD50 0.0005 mg/kg

blocks Ach release

Example botulinum toxin

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Compounds of concern in food toxicology

• additives • indirect additives (from packaging material) • animal drugs • pesticide residues • nonfunctional/ unavoidable contaminants • natural toxins • novel food ingredients • food supplements • substances from cooking/ processing

Functional foods & food supplements

caffein improves cognitive performance calcium prevents osteoporosis luteolin improves the eyes PUFA lower cholesterol levels AOX are anti-carcinogenic, prevent artherosclerosis

but… more of a healthy ingredient does not always improve health

Paracelsus (1493-1541)

“Alle Ding sind Gifft … allein die Dosis macht dass ein Ding kein Gifft ist”

notion of dose

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Example: Beta-carotene epidemiologic studies reveal: carotenoid-rich diets: reduced risk on lung cancer, cardiovascular diseases, cataract carotenoid-deficient diets: increased risk on lung cancer

Randomized intervention studies

29.133 /18.314 smokers, male, 50-69 years old

20 / 30 mg b-carotene /day, 5-8 years follow-up

New Eng J Med 330 (1994) 1029-1035 ATBC study

New Eng J Med 334 (1996) 1150-1155 CARET study

Beta-carotene

Beta-carotene

4-5 times increase in plasma levels causes adverse effect

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Compounds of concern in food toxicology

• additives • indirect additives (from packaging material) • animal drugs • pesticide residues • nonfunctional/ unavoidable contaminants • natural toxins • novel food ingredients • food supplements • substances from cooking/ processing

substances from cooking/ processing

substances produced by cooking/ processing high temperature cooking/frying proteins: • HCAs: heterocyclic

amines (PhIP in hamburgers) • acrylamide • PAHs: Polycyclic Aromatic Hydrocarbons like benzo(a)pyrene

acrylamide in chips, french fries, bread

carcinogenic in animal studies IARC: group 2A “probably carcinogenic to humans” calculated cancer risk: at estimated daily intake in NL of 0.4 mg/kg bw /day: about 100 persons / year 500 x 10-6/ lifetime : action to be taken

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Acrylamide: actions taken?

C C

In 2007 some products higher levels

Acrylamide: risk assessment

AA and GA are genotoxic: no TDI

neurotoxicity (periferic neuronopathy in rats) BMDL10 = 0.43 mg/kg bw per day MOS values compared to EDI across the age groups 100-1000 so > 100: no risk for a thresholded endpoint Carcinogenicity: lowest BMDL10 = 0.17 mg/kg bw per day MOE values 40-400 << 10 000 Of concern! Risk management actions required

Future perspective

Quantitative Risk assessment DALY’s (Disability Adjusted Life Years) Risks expressed in the number of lost healthy life years in the population

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Example DALY’s: acrylamide in chips, french fries, bread

Caluclated cancer risk: At EDI in NL 0.4 mg/kg bw /day: 100 persons / year

Assumption: cancer: 5 year reduction in life expectancy 500 DALY’s healthy life years lost / year

DALY’s allow comparison of different health risks

Chemical risks food safety <1000 DALY’s Other health risks: • Food infections 1000 - 4000 DALY’s • coronairy heart diseases 350.000 DALY’s

DALY’s other risk factor:

Conclusions

food toxicology: • many existing but also newly emerging items • thanks to good regulation and control health risks are limited:

our food has never been safer

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© Wageningen UR

Thank you for your attention !