Food Toxicology
2nd SEMESTER, 2018/2019 SESSION Lecturer: Prof Monia Perugini E-mail [email protected] 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 Food Intake Health Risks
Microbiological Risks Toxicological 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 What Exactly We Ingest When We Eat Food: Glazing agents – 5 Flavoring agents – 3 An example: Common Food X Emulsifiers – 8 Antioxidants – 6 Colors – 2 Butylate Hydroxyanisole Sweeteners – 11 Chronic exposure – gall bladder, endocrine, Bulking agent – 1 lungs, thorax respiration tumors Mutagen – DNA inhibition, unscheduled Processing aid – 1 DNA synthesis, DNA damage Chronic exposure – reproductive damage Prolonged repeated exposure can cause allergies in sensitized individuals Food X: Chocolate 200 mg/kg
Concept
Hexane Flammable Delayed target organ effect Peripheral nervous system Kidney Testes-tumors Reproductive effects Potentially carcinogenic 1 mg/kg
FDA states that – Safety can not be proved absolutely but….
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
General Principles of Risk Analysis Risk is associated with hazard & exposure First Step: Hazard Identification – Formaldehyde causes cancer – Cholera toxin causes severe diarrhea 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) 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. Toxicology and Risk Analysis
• 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. 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 2. Half-life
- Biological half-life: this is the period of time required
for the concentrations or amount of drug Compond Half-life in the body to be reduced by one half. DDT 15 years Lindane 2 years Parathion 130days Malathion 11 days
Non dobbiamo dimenticare che …… . . . “Tutte le sostanze sono dei veleni; non ne esiste una che non sia un veleno. La giusta dose differenzia un veleno da un rimedio” “E’ la dose che fa il veleno” - Paracelsus 1493-1541
SOME DEFINITIONS
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 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)
Maximum Efficacy B 100 A
% Maximum Response 50
0 0 X DRUG DOSE
B has greater max efficacy than A ~ Potency B 100 A
% Maximum Response 50
0 0 X DRUG DOSE
A is more potent than B ~ 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?
How Toxicity Is Assessed ?
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
55 Toxicity can be
Acute Toxicity: a toxic Chronic Toxicity: a response ,often toxic effect that immediate, induced requires some time to by single exposure. develop. The acute toxicity of a Testing for chronic substance is defined toxicity involve
by its LD50 / lethal continuous feeding of dose that will kill 50% the test substance to of a group of exposed animals for long time animals (50% of animal life)
Chronic Toxicity 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.
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. NOEL Toxicological ADI = Safety Factor
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. 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 NOEL(ug/kg bw/day) = ADI (ug/kg bw/day) safety factor
ADI x 60 kg = Safe Concentration consumption factor (Provide total drug residues allowed in each edible tissue) 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 Enrofloxacin– Determination of a Toxicological ADI Summary of Toxicology Studies Conducted to Establish the ADI
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
NOEL 3 mg/kg bw/day Toxicological ADI 0.003 mg/kg/day Safety Factor 1000 Determination of the Final ADI
Toxicological ADI = 0.003 mg/kg bw/day (or 3 µg/kg/day) Final ADI = 0.003 mg/kg bw/day Calculation of Safe Concentrations
ADIHuman Weight Safe Concentration (SC) Food Consumption Value 3 µg/kg bw/day 60 kg Food Consumption Value (g)
Edible Tissue Food Consumption (g) Calculated SC (ppm) Muscle 300 0.6 Liver 100 1.8 Kidney 50 3.6 Fat 50 3.6 Question is:Is it acceptable for an individual to exceed the ADI on any given day?
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
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 Texas -30 Cormorano dalla Wisconsin -30 doppia cresta Falco pellegrino California -26 Pellicano bianco British Columbia -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
Absorption Ingestion Inhalation (lung) Skin (dermal)
Home Exposure Occupational Exposure Other Exposure
Farms & Farm worker Dietary exposure Accidental ingestion • Pesticide Pesticide applicator Lawn and garden use residues on Manufacture Insect control crops Mixing and handling Food supply Community exposure Landscapers • Airborne drift Water supply Many more …… Contaminated drinking water • Leaching from soils to ground water Mechanism of Action
Oganochlorines & Pyrethroids - Enzymes, axonal membranes (Na+, K+, Ca++, Cl-)
Organophosphates & Carbamates Organochlorines bind - excess acetylcholine 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 Skin Effects of Organochlorines
DDT Chloracne Lindane Irritant reactions Negative in patch test series
101 Skin Effects of Organochlorines Dienochlor
Patch test develops hyperpigmentation in 15- 20% of subjects tested with dienochlor - resembles reaction to Balsam of Peru Cl Cl Cl Cl
Cl Cl Cl Cl Dienochlor
102 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.
103 Photo courtesy of California Poison Control System Poison Control ofPhoto courtesy California Organochlorines in food Organochlorines in food
Insecticide Illness:
Occupational and environmental exposure Toxicity varies by chemical class Specific therapy limited Prevent illness by reducing use
Source: USDA Source:
107 Dioxins and furans 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)
109 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 110 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
111
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)
113 Dioxins in the environment
E.g., USA dietary intake of dioxins 114 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)
115 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 costs116 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
117
Legislation