Food Toxicology

2nd SEMESTER, 2018/2019 SESSION Lecturer: Prof Monia Perugini

E-mail mperugini@unite.it Phone: 0861266988

W E L C O M E !

Course requirements

CFU = 4 (total 32h of course)

Number of units: 4 units

Lecture period: 4 hours /week (32 hours/total)

One Practical period 12 or 16 hours/total

Grading

Final Examination 100%

Course Learning

Objectives

Upon successful completion of the course students should:

Have broad base knowledge about sources, nature and control of toxic substances in human food system

Acquire critical thinking and analytical skills in risk assessment

Have a high level of understanding and interpretative capacity in food science and toxicology interface.

General program

1. Definitions of terms; concepts of

toxicology, acute and chronic toxicity food

and safety

2. Pesticide residues

3. Naturally occuring toxins (Mycotoxins,

Glycoalkaloids, Marine biotoxins)

4. Food additives

(Antioxidants,Preservatives,Colourants,E

mulsifiers and Stabilisers, Sweetners)

FOOD

TOXICOLOGY

Toxicological Risks

Health Risks Food Intake

Microbiological Risks

Infection Intoxication

What is food safety?

Potential health risks from food

consumption

microbiological, viral and parasitic concerns

hormone residues (growth promoters)

animal drugs (antibiotics)

chemical residues (pesticides)

preservatives

genetically modified foods (GE)

Food Safety is everyone’s

responsibility

Food safety— What needs to be regulated?

• Food additives

• Food labeling

• Dietary supplements

• Novel and GE foods

• Food security and protection of food supplies

Food Safety Systems—Institutions

• OECD: Organization for Economic

Cooperation and Development

– Promotes policies for highest sustainable

economic development in member states

– Establishes guidelines for chemical testing,

toxic chemicals, pesticides, and

biotechnology

• Food and Agriculture Organization

(FAO) of the United Nations

– Leads international efforts to ensure

sufficient nutrition for all

• World Health Organization (WHO)

of the United Nations

– Provides scientific advice on matters related

to food safety through its Food Safety

Department

The Evolution of Food Safety Systems

The Codex Alimentarius Commission has issued (since 1963)

237 Food standards for commodities

41 Codes/Hygiene or technological practice

25 Guidelines for contaminants

185 Evaluations on pesticides

1,005 Evaluations on food additives

54 Evaluations on veterinary drugs

3,504 Documents/Limits pesticide residues

Acidity regulators – 17

Glazing agents – 5

Flavoring agents – 3

Emulsifiers – 8

Antioxidants – 6

Colors – 2

Sweeteners – 11

Bulking agent – 1

Processing aid – 1

Hexane

Flammable

Delayed target organ effect

Peripheral nervous system

Kidney

Testes-tumors

Reproductive effects

Potentially carcinogenic

1 mg/kg

Butylate Hydroxyanisole

Chronic exposure – gall bladder, endocrine,

lungs, thorax respiration tumors

Mutagen – DNA inhibition, unscheduled

DNA synthesis, DNA damage

Chronic exposure – reproductive damage

Prolonged repeated exposure can

cause allergies in sensitized individuals

200 mg/kg

Concept

Food X: Chocolate

What Exactly We Ingest When We Eat Food: An example: Common Food X

In order to achieve the general objective of a high level of protection of human health, EU feed/food legislation shall be based on risk analysis (process consisting of three interconnected components: risk assessment-risk management-risk communication) except where this is not appropriate to the circumstances or the nature of the measure

Risk assessment shall be based on the available scientific evidence and undertaken in an independent, objective and transparent manner

FDA states that – Safety can not be proved absolutely but….

General Principles of Risk Analysis

Second Step: Hazard Characterization

– Quantitative and qualitative assessment of the nature of the hazard

– Dose-response relationship

– Usually animals are administered 3 doses: very small to doses that exceed multiple orders of what would be expected to determine NOAEL=(No Observed Adverse Effect Level)

– Margin of safety determination:

– To account for interspecies and intra-species variation, NOAEL is divided by 100 (uncertainty factor)

Risk is associated with hazard & exposure First Step: Hazard Identification

– Formaldehyde causes cancer

– Cholera toxin causes severe diarrhea

A hazard is something that can cause harm, e.g.

electricity, chemicals, stress, etc.

A risk is the chance, high or low, that any hazard will

actually cause somebody harm.

• Risk assessment

– Scientific evaluation of the probability of harm resulting from exposure

to toxic substances.

• Risk management

– Risk management is the decision-making process involving

considerations of political, social, economic and science/engineering

factors with relevant risk assessments relating to a potential hazard so

as to develop, analyze and compare options and to select the optimal

• Risk communication

– The science of communicating effectively in situations that are of high

concern, sensitive, or controversial. Risk communication principles

serve to create an appropriate level of outrage, behavior modification,

or mitigating response, that is in direct proportion to the level of risk or

Hazard.

Toxicology and Risk Analysis

Concern Level, Tolerance Levels

Are required for

Pesticide residues

Drugs used in food producing

animals

Heavy metals

Food-borne molds and mycotoxins

Bacterial toxins

Substances produced by cooking

SOME DEFINITIONS

Safety: is the absence of evidence of

toxicity

Toxicity: is ability to cause harm/adverse

effect

Toxin/poison: poisons are substances that

cause harm to organisms when sufficient

quantities are absorbed, inhaled or

ingested. A toxin is a poisonous substance

produced within living cells or organisms.

SOME DEFINITIONS

TOXICOLOGY: multi-disciplinary

application of scientific knowledge to the

study of toxins and their effects on people,

animals, wildlife and the environment.

FOOD ADDITIVES: Any

substance/mixture of substances other

than the basic component that is added to

food as a result of any aspect of

processing, storage and preservation.

Toxicology is the most diversified of all

scientific disciplines, so toxicologists

usually specialize in some aspect of

toxicology

Medical Toxicology/ Clinical Toxicology:

diagnosis and treatment of human diseaeses

caused by poisons

Veterinary Toxicology: diagnosis and treatment

of diseases of domesticated and wildlife caused

by poisons

Food Toxicology: is the study of the nature,

properties, effects and detection of toxic

substances in food and their disease

manifestation in humans

Forensic Toxicology: deals with the legal

and medical aspects of poisons in people

and animals;

Environmental Toxicology: deals with effects

of pollutants on the environment and wildlife.

Regulatory toxicology:use scientific data to

decide how to protect humans and animals

from excessive risk.

SOME DEFINITIONS

Contaminant or pollutant?

Natural sources Antropogenic sources

Food contaminants are compounds

included unintentionally in foods.

Some are harmless and others are

hazardous because of the

toxicological risks from their intake to

the consumers.

Sea = Pollutants

How can we

measure the

chemicals in food?

1. Concentrations units

ppm = 1 part per million = 1 mg/Kg or 1µg/g or 1mg/L

ppb = 1 part per billion = 1 ug/Kg or 1 ng/g or 1 ug/L

ppt = 1 part per trillion = 1 ng/Kg or 1 pg/g or 1 ng/L

- Biological half-life: this is the period of time required

for the concentrations or amount of drug

in the body to be reduced by one half.

2. Half-life

Compond Half-life

DDT 15 years

Lindane 2 years

Parathion 130days

Malathion 11 days

Non dobbiamo dimenticare che

…… . . .

“E’ la dose che fa il veleno” - Paracelsus 1493-1541

“Tutte le sostanze sono dei veleni; non ne esiste una che non sia un veleno. La giusta dose differenzia un veleno da un rimedio”

Safety is relative and there is no absolute safety

Thus there are toxic and non toxic doses for any substance

Frequency-response curve: a plot of the % of individual with specific response as a function of dose

SOME DEFINITIONS

Dose amount of drug per body

weight expressed as mg/kg

Dosage total amount of a drug

administered to an organism.

Important:

Characteristics of organism

Body weight

DOSE-RESPONSE CURVES The dose–response relationship,

or exposure–response relationship,

describes the change in effect on

an organism caused by differing levels of

exposure (or doses) to a stressor (usually

a chemical) after a certain exposure

time. This may apply to individuals (e.g.: a

small amount has no significant effect, a

large amount is fatal), or to populations (e.g.:

how many people or organisms are affected

at different levels of exposure).

Cumulative response-curve

(compounds A and B)

DRUG DOSE 0 X

Maximum Efficacy

B has greater max efficacy than A ~

A

B

% Maximum

Response

0

100

50

DRUG DOSE 0 X

Potency

A is more potent than B ~

A

B

% Maximum

Response

0

100

50

Dose – response curve for an

essential nutrient

Dose response curves

Dose response relationships describe the effect on an organism caused by differing levels of exposure (or dose)

Dose levels are usually expressed in mg/kg body weight of the test animal for solids and mg/m3 or parts per million for aerosols/vapours

The dose response curve is a valuable tool to understand the levels at which substances begin to exert adverse effects and the degree of harm expected at various levels

How the chemicals can enter in our body?

55

In vitro/animal studies Systemic toxicity studies (such as clinical signs and symptoms,

clinical pathology, histopathology)

Special functional tests (e.g., reproductive performance, immune

system function, neurological tests)

Human studies Epidemiological studies

Human clinical studies

Case reports

How Toxicity Is Assessed ?

Toxicity can be

Acute Toxicity: a toxic

response ,often

immediate, induced

by single exposure.

The acute toxicity of a

substance is defined

by its LD50 / lethal

dose that will kill 50%

of a group of exposed

animals

Chronic Toxicity: a

toxic effect that

requires some time to

develop.

Testing for chronic

toxicity involve

continuous feeding of

the test substance to

animals for long time

(50% of animal life)

Studies used to determine the safe Level of Exposure

Determine NOEL or LOAEL from dose-response curves

obtained from toxicology studies

Determine the uncertainty factors to extrapolate the

results from animal studies to humans.

Chronic Toxicity

The dose-response curve LD50 = 50% of species

exposed to dose die (Oral

route)

measured in mg/Kg

LC50 = 50% of species

exposed to concentration

die (Inhalation route)

measured in ppm or mg/m3

NOAEL – Highest dose at

which there is No Observed

Adverse Effect Level. Some

dose response curves may

not have a threshold,

starting at zero.

Lowest observed adverse

effect level (LOAEL)

NOAEL/NOEL

The appropriate NOEL is divided by a

“safety factor” to obtain an “acceptable

daily intake” (ADI), which is the amount of

drug residue per kilogram body weight per

day that can be consumed daily over the

lifetime of a human without harmful effect.

ADI serves to protect the health of consumers. Generally, as

a result of toxicology assessment, a human ADI for total drug

residues is established and the safe concentration for each

edible tissue is calculated.

FactorSafety

NOELToxicological ADI =

Safety Factors

Variability between humans 10X

Interspecies extrapolation 10-100X

Subchronic extrapolation 10X

Total possible 0-10,000X

Firstly, the NOAEL is determined in animals, not humans. It is therefore

prudent to adjust for possible differences by assuming that man is more

sensitive than the most sensitive test animal.

Secondly, the reliability of toxicity tests is limited by the number of animals

tested. Such tests cannot represent the diversity of the human

population, subgroups of which may show different sensitivities (e.g.

children, the old and the infirm). Again, it is prudent to adjust for these

differences.

Safe Concentration for

Total Chemical Residues

ADI (ug/kg bw/day) NOEL(ug/kg bw/day) = safety factor

Safe Concentration ADI x 60 kg = consumption factor

Edible Tissue/Product Food Consumption

(per person per day)

Muscle 300 g

Liver 100 g

Kidney 50 g

Fat/skin 50 g

Eggs 100 g

Milk 1.5 L

(Provide total drug residues allowed in each edible tissue)

mg/kg/day 003.01000

bw/daymg/kg3

FactorSafety

NOELADI calToxicologi

Study Type NOEL (mg/kg

bw/day)

Subchronic oral toxicity study in dogs 3

Chronic toxicity and carcinogenicity study in mice 323

Chronic toxicity in rats 5.3

Two-generation reproductive toxicity study in rats 125

Embroyotoxicity/teratogenicity study in rabbits 25

Summary of Toxicology Studies Conducted to Establish the ADI

Enrofloxacin– Determination of a Toxicological

ADI

Toxicological ADI = 0.003 mg/kg bw/day

(or 3 µg/kg/day)

Final ADI = 0.003 mg/kg bw/day

Determination of the Final ADI

Calculation of Safe Concentrations

(g) ValuenConsumptioFood

kg 60bw/day µg/kg 3

ValuenConsumptioFood

WeightHumanADI(SC) ionConcentrat Safe

Edible Tissue Food Consumption (g) Calculated SC (ppm)

Muscle 300 0.6

Liver 100 1.8

Kidney 50 3.6

Fat 50 3.6

The consumption of an additive/drugs above its

ADI on a given day is not a cause for concern

because the ADI has a large built-in safety factor

and in practice, consumption above the ADI on

one day is more than accounted for by

consumption below the ADI on most other days.

ADI is not a reference value for a single

occasion but for long exposure situation

However, if the ADI may be regularly exceeded by

certain sectors of the population, it may be

necessary for the European Food Safety Authority

to advise a reduction of levels in foods consistent

with the amount needed to achieve its function, or

to reduce the range of foods in which the additive

is permitted for use.

Hg pregnant women

Question is:Is it acceptable for an individual to exceed the

ADI on any given day?

Drugs or contaminants?

Food Contamination and Safety

Persisten organic pollutants (POPs) Inorganic pollutants

Persistent Organic Pollutants

(POPs)

Organic compound

containing chlorine

Organochlorines

• 1945 control of mosquitoes

• Effective but very persistent

• Very soluble in fat

• Damaged bird eggs

Distribution

Shell variations in the eggs of the seabirds

Specie Località Variazione % dello spessore

Aquila calva

Cormorano dalla doppia cresta

Falco pellegrino

Pellicano bianco

Texas

Wisconsin

California

British Columbia

-30

-30

-26

-14

An extra link, on top of an already

long food chain

Environmental hazard

Environmental hazard of insecticides is

generally evaluated as a function of

persistence often compared to

effectiveness

High – Environmental persistence far greater

than period of effectiveness (> 5 months and

often > a year)

Intermediate – Persists beyond

effectiveness (3-5 month half-life)

Environmental hazard

Low – Persists about the period of effectiveness

(up to about 3 months) and then degrades

completely over several months

Very low – Persists for short periods (>45 days)

and degrades completely

Ingestion

Inhalation (lung)

Skin (dermal)

Absorption

Home Exposure Occupational Exposure Other Exposure

Dietary exposure

• Pesticide

residues on

crops

Community exposure

• Airborne drift

Contaminated drinking water

• Leaching from

soils to ground

water

Farms & Farm worker

Pesticide applicator

Manufacture

Mixing and handling

Landscapers

Many more ……

Accidental ingestion

Lawn and garden use

Insect control

Food supply

Water supply

Mechanism of Action

Oganochlorines & Pyrethroids

- Enzymes, axonal membranes

(Na+, K+, Ca++, Cl-)

Organophosphates &

Carbamates

- excess acetylcholine Organochlorines bind to sodium channels in

neurons increasing permeability to

sodium

Organochlorines

Most have been banned in the U.S.

DDT was banned from US use in the

1970s

Very few still available for our use

Endosulfan is sometimes used on

ornamentals and in seed orchards

Lindane is still registered for Southern Pine

Beetle control but no product is available in

the marketplace

Organochlorines

Toxicity Acute toxicity variable, CNS – convulsions,

coma

Organochlorines interact with endocrine

receptors which may affect reproductive

processes

CNS alterations as myoclonus and seizures

High organochlorine levels may cause

myocardial instability and arrythmias

Children are particularly vulnerable

Organochlorine Toxicity

CNS toxicity

Headache, dizziness, irritability, incoordination,

tremor, seizures, paresthesia (DDT),

Carcinogenicity

Hepatic tumors in rodents

Breast cancer (?)

Endocrine disruptors

101

Skin Effects of Organochlorines

DDT

Chloracne

Lindane

Irritant reactions

Negative in patch test series

102

Skin Effects of Organochlorines

Dienochlor

Patch test develops

hyperpigmentation in 15-

20% of subjects tested

with dienochlor -

resembles reaction to

Balsam of Peru

ClCl

Cl Cl

Cl

Cl Cl

Cl

Dienochlor

103

Case

Child With Seizures

9 year-old child with myoclonic seizures

witnessed by parents. No history of seizures,

head trauma, etc.

In ER, child sleepy, oriented; complaining of

abdominal cramping, throat burning. Exam

normal.

Photo

court

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Organochlorines in food

Organochlorines in food

107

Insecticide Illness:

Occupational and environmental exposure

Toxicity varies by chemical class

Specific therapy limited

Prevent illness by reducing use

So

urc

e: U

SD

A

Dioxins and furans

109

Dioxins

Dioxins: a family of compounds including PCDDs & PCDFs with Cl atoms at any of the 8 sites on the benzene rings.

→ 210 possible congeners

PCDD: Polychlorinated dibenzo-p-dioxin (75 congeners)

PCDF: Polychlorinated dibenzofurans (135 congeners)

110

Dioxins A particularly important dioxin is 2,3,7,8-tetrachlorodibenzo-p-

dioxin, or TCDD:

This compound is the most toxic chemical compound ever evaluated by the EPA!

TCDD half-life in the body is 7 years

In common with other POPs, dioxins have:

- low vapour pressures

- low solubility in water (hydrophobic)

- good solubility in organic solvents, oils, and fats (lipophilic)

→ bioconcentration

111

Sources of dioxins

Dioxins are produced when organic material is burned in presence of chlorine (from Cl- ion or an organochlorine compound)

Widely produced. Major sources are: - incineration of municipal & medical waste - coal-fired utilities - metal smelting - diesel trucks - burning treated wood - misapplication of sewage sludge - bleaching of paper fibres and textiles Dioxins are largely anthropogenic Most dioxins (>99%) are found in the topsoil

113

Dioxins in the environment Dioxins are widespread – all people exposed to a low

background concentrations of dioxins

Human exposure:

- > 90% of human intake is through food

- fish, meat, and dairy are most important sources

- concern about dioxin exposure in infants and breast-fed children owing to greatly elevated intake of dioxins

Besides background exposure, people may also be exposed to

dioxins through accidental exposure (e.g., the Seveso Disaster) or occupational exposure (e.g., in some chemical industries).

Mean intake: 50 – 200 pg/day for an adult (60 kg)

114

Dioxins in the environment

E.g., USA dietary intake of dioxins

115

Health effects of dioxins

Adverse health effects associated with dioxins include:

- cancer

- immune system damage

- birth defects

- diabetes

- endocrine disruption

- chloracne

Different congeners have different toxicities. Relate toxicities

using the Toxic Equivalence Factor (TEQ). This factor is

defined as 1 for TCDD.

Tolerable Daily Intake (TDI) = 10 pg / kg body weight (TCDD)

116

Dioxin poisoning (1) The Seveso Disaster (July 1976)

An industrial accident in the Italian town of Seveso, 25 km from

Milan, resulted in the highest exposure of residential

population to TCDD.

About 800 residents were exposed to high TCDD concentrations

Over 3000 animals died within days of the accident

Emergency slaughtering of tens of thousands of animals was

undertaken to prevent the introduction of dioxins into the food

chain

Complete evacuation of nearby area

- hundreds of cases of chloracne & skin lesions

Subsequent costs include compensation to victims & clean up costs

117

Dioxin poisoning (2) Victor Yushchenko (September 2004)

Ukrainian opposition leader, Victor Yushchenko,

became acutely ill during the 2004 Ukrainian

elections

Hospitalised in Vienna with “acute pancreatitus”

Dutch toxicologist suggested testing for dioxin

levels

Dioxin concentrations found to be 1000 times

higher than normal

Legislation