tox 2 finals Flashcards
what is food toxicology
Food toxicology is the study of the nature, properties, effects, and detection of toxic substances in food, and their disease manifestation in humans
safety concerns should focus on….
safety concerns should focus on both the nature of the substance and its intended conditions of use
Tox studies focus on what portion the most
- focus on digestion and metabolism occurring in the GI tract
-The reason for this focus is that in most cases it is not the ingested substance that is absorbed through the GI tract; it is products of its digestion that are absorbed.
the two major problems in regulation are
Two major problems
Toxic colors and preservatives “
Patent “quack” medicines
What is GRAS
Generally regarded as safe
Scientific experts determine whether a substance that is to be added to a food is GRAS.
In addition to GRAS the FD&C Act provides a class of substances that are regulated as food additives, which are not generally recognized to be safe.
Hence there is a legal distinction between GRAS and Food additives
what is poison squad
first regulatory agency that looked after certain meals
what was the upton sinclair jungle 1906
Novel about meat processing industry
Unsanitary conditions and practices for workers
Rats in meat plants
what was he federal meat inspection act
Mandatory inspection of livestock before slaughter
Mandatory postmortem inspection of every carcass Sanitary standards established for slaughterhouses and meat processing plants
Authorized U.S. Department of Agriculture ongoing monitoring and inspection of slaughter and processing operations.
what was the pure food and drug act
First comprehensive federal food law
Considerable opposition from industry
Many legal cases pointed out strengths and weakness in law
Many good things
Needed work
problems:
Food adulteration still common
Few purity food standards
Food color, water, grass seed, pectin = fruit jam
Limited analytical techniques
Weak on food & drug safety
Burden of proof on FDA
what was elixir of sulfanilamide
raspberry flavored death
medicine that was taken
children died
Food drug and cosmetic act
Included cosmetics, therapeutic devices
Pre-market safety testing of drugs
Toxic substances prohibited in foods unless unavoidable or required in processing Authority for factory inspections
Proof of fraud no longer required to stop false claims
-Previously only the maker had to believe efficacy
Safe tolerances were authorized for pesticide residues
Standards were developed for many foods
what was the delaney clause
No chemical can be added to food or animal feed that has been shown to be a carcinogen by appropriate tests (animal studies)
Zero tolerance/zero risk
Dilemma for cumulative and non-cumulative pesticides - Sections 408 and 409
Food Quality Protection Act 1996
Abolished Delaney Clause for pesticides
Negligible risk (1 in a million ) for carcinogens, de minimus No residue in edible portion
10x safety factor for children
Risk cup
what are tolerances
A food may be declared unfit if it contains unavoidable contaminant that may render the food injurious.
But, an unavoidable contaminant in food, need only pose a risk to be found unfit and subject to FDA action.
At times, foods containing unavoidable contaminants cannot be banned.
Under provisions of Sec 406 of the FD&C Act, the quantity of the unavoidable contaminant in food may be limited by regulation.
Ex: Action levels for Aflatoxin in peanuts, grain, and milk.
what are food additives
A substance which may, by its intended use, become a component of food, either directly or indirectly, or which may otherwise affect the characteristics of food.
Includes any substance intended for use in producing, manufacturing, processing, preparing, treating, packaging, transporting or holding food, and any source of radiation intended for such use
what are the rules for exempt chemicals
GRAS (Generally Recognized as Safe)
From scientific studies or wide usage
Salt, vitamins, etc.
GRAS - qualified experts determined safe
May not be FDA decision (GRAS)
Company can self-proclaim (GRAS)
“Prior Sanctioned” before 1958
Prior sanctioned – approved by FDA/USDA prior to 1958
Sodium nitrite, etc.
what are regulated food additives
Food additives that are not color, or GRAS, or prior sanctioned
Require FDA approval
-Scientific data that no harm will occur
“Redbook” guidelines
Must justify function
32 categories (C&D)
food addtives have to go through FDA approval
what are color additives
Same testing as food additives
Not eligible as GRAS
Tested at all FDA concern levels
-Two types
=Certified - by FDA chemists for purity
=Exempt - mostly naturally occurring
what are certified color additives
Prefix of FD&C
Two exemptions: Orange C, Citrus Red 2
Every batch must be FDA certified
Aromatic amines, aromatic azos
Unusually nontoxic for these compounds
what are exempt color additives
Usually naturally occurring
Dried algae, beet powder, grape skin extract, fruit juice, caramel, etc.
Lack precise chemical identity
Fade readily, lack intensity and uniformity
Higher levels required
Used less (except caramel)
what is reference dose
An estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. Can be derived from a NOAEL, LOAEL, or benchmark dose, with uncertainty factors generally applied to reflect limitations of the data used.
what is ADI
Acceptable Daily Intake (ADI): The amount of a chemical a person can be exposed to on a daily basis over an extended period of time (usually a lifetime) without suffering deleterious effects
what are indirect food additives
not directyy added to food
may enter food through migration of packaging materials holding containers or processing surfaces
cans plastics
indirect food additives toxicity testing
Negligible migration (< 0.05ppm) and EDI < 0.15mg/person/day
Acute toxicity studies only
Migration 0.05-1.0ppm
Subchronic studies; 2 species
Migration > 1.0ppm
Chronic studies; 2 species
Carcinogenicity
Multigenerational reproduction
Teratology
what is DSHEA
The Dietary Supplements Health and Education Act (DSHEA) was established in 1994 to provide the legal framework specifically for dietary supplements
Under the DSHEA, no claim can be made for a dietary supplement to treat, cure or mitigate a disease.
However, a dietary supplement can make claims that it affects or maintain the structure or function of the body
FDA Carcinogenic Constituent Policy For Non-functional Carcinogenic Contaminants of Food Additives
Delaney is not invoked
Health effects may be negligible
RA model
Upper bound lifetime risk in humans < 1 in million above background
-Many conservative estimates made in model
-Possibly over estimates risk by million-fold
interpretation of delaney: Food additives
Risk Assessment cannot be used if food additive is carcinogenic
Zero tolerance policy
Very strict regulation
FDA requires clear, unequivocal, reproducible evidence for cancer
Few substances banned
Must be primary carcinogen
Secondary carcinogenesis not considered evidence
1959 Cranberrry incidecet
Aminothiazole residues detected in cranberry products (Delaney Clause) Recall of cranberry products during Thanksgiving - Public impact!
1959 Cranberrry incidecet
Aminothiazole residues detected in cranberry products (Delaney Clause) Recall of cranberry products during Thanksgiving - Public impact!
The delaney clause for food additves shwos
Applies to: Regulated food additives, color additives and drugs
Does not apply to: Unavoidable contaminants, GRAS substances, prior sanctioned ingredients or non-functional trace contaminants
what is secondary carcinogenesis
Nutritional, hormonal, physiological imbalances are secondary causes of cancer
Secondary carcinogens only contribute to increase (promote) effect
No evidence of direct genotoxicity
Example: BHA
=Chronic irritation = tissue damage = hyperplasia = cell proliferation = increased =chance for mutation and cancer
substances banned by delaney
Packaging materials - Flectol H, mercaptimidazoline
Food additives - safrole, cinnamyl anthranilate, thiourea, diethylpyrocarbonate (forms urethane) Primary carcinogens
what are adverse reactions to food
Definition: General term that can be applied to a clinically abnormal response attributed to an ingested food or food additive
Characteristics/Example: Any untoward pathological reaction resulting from ingestion of a food or food additive. May be immune mediated.
what are food allergy symptoms
Respiratory = asthma, wheezing, bronchiospasms, dyspnea (shortness of breath) Cutaneous = urticaria (hives), eczema, rash, pruritis
Gastrointestinal = vomiting, diarrhea, abdominal pain
Inflammation, vasoconstriction, hypotension, chest pain, nausea
Other = anaphylaxis
Mild and annoying to fatal
Depend on amount ingested and length of time from initial exposure Not all symptoms in all people
what is food intolerance
Definition: A general term describing an abnormal physiologic response to an ingested food or food additive; this reaction may be an immunologic, idiosyncratic, metabolic, pharmacologic, or toxic response
Characteristics: Any untoward pathologic reaction resulting from ingestion of a food or food additive. May be immune-mediated.
Example: Celiac disease (intolerance to wheat, rye, barley, oats)
what is Food Toxicity (Poisoning)
Definition: A term used to imply an adverse effect caused by the direct action of a food or food additive on the host recipient without involvement of immune mechanisms. This type of reaction may involve non immune release of chemical mediators. Toxins may be contained within food or released by microorganisms or parasites containing food products
Characteristics/examples: Not immune mediated. May be caused by bacterial endo- or exotoxin, fungal toxin, tetrodotoxin from pufferfish, domoic acid from mollusks, histamine poisoning from fish, nitrate poisoning from processed meat
what is food idiosyncrasy
Definition: A quantitatively abnormal response to a food substance or additive; this reaction differs from its physiologic or pharmacological effect and resembles hypersensitivity but does not involve immune mechanisms. Food idiosyncratic reactions include those which occur in specific groups of individuals who may be genetically predisposed.
Characteristics/examples: Not immune-mediated, Favism (hemolytic anemia related to deficiency of erythrocytic glucose-6-phosphate dehydrogenase), fish odor syndrome, lactose intolerance, asparagus urine, red wine intolerance
Anaphylactoid Reaction to a Food
Definition: An anaphylaxis-like reaction to a food or food additive as a result of non-immune release of chemical mediators. This reaction mimics the symptoms of food hypersensitivity (allergy)
Characteristics/examples: Not immune mediated. Scombroid poisoning, sulfite poisoning, red wine sensitivity
what is pharmalogical food reaction
Definition: An adverse reaction to a food or food additive as a result of a naturally derived or added chemical that produces a drug-like or pharmacologic effect in the host
Characteristics/Examples: Not immune mediated. Tyramine in patients treated with MOA inhibitors, fermented food in disulfiram treated patients
what is metabolic food reaction
Definition: Toxic effects of a food when eaten in excess or improperly prepared
Examples: Glycyrrhizism, vitamin A toxicity, goitrogens
what is risk assessment
The systematic scientific characterization of potential adverse health effects resulting from human exposures to hazardous agents or situations
what are risk assessments requirements
Qualitative information about the strength of the evidence and the nature of the outcomes
Quantitative assessment of the exposures
Host susceptibility factors
Potential magnitude of the risk
Description of the uncertainties in the estimates and conclusions
Describe Characterization of Risk
Risk assessment often results in an overly precise risk estimate
Frequent ignorance of:
Crucial information about mechanism of toxicity
Species variability
Inconsistent findings across studies
Multiple variable health effects
Means of avoiding or reversing the effects of exposures
What is the risk assessment paradigm
Risk Characterization
Estimates the incidence of a health effect under the various conditions of exposure described in exposure assessment
Performed by combining the hazard identification, exposure assessment, and dose-response assessment
Describes the summary effects of the uncertainties in the preceding steps
Qualitative risk characterization
-Narrative; semi-quantitative terms such as “negligible”, “minimal”, “moderate”, “severe”, and “acceptable”
-Comparisons to common hazards and risks: “less than”, “equal to”, or “greater than”
Quantitative risk characterization expresses hazard and risk in numerical terms; amount of hazard per unit dose or exposure of an agent, e.g., percent change in response for each mg/kg of toxic agent
4 key steps in risk assessment
Hazard identification, dose response assessment, exposure assessment and risk chrachterization
what is risk management
Process by which policy actions are chosen to control hazards identified in risk assessment
Risk managers consider the following:
Scientific evidence
Engineering, economic, social, and political factors
Risk Management framework 6 stages
1Formulating the problem in a broad public health context
2Analyzing the risks
3Defining the options
4Making risk-reduction decisions
5Implementing those actions
6Evaluating the effectiveness of the actions taken
What is risk communication
Challenging process of making risk assessment information comprehensible to the community (lawyers, elected officials, workforce, environmentalists)
what is the national research council
Risk Assessment in the Federal Government: Managing the Process (“The Red Book”)
Detailed steps of hazard identification, dose-response assessment, exposure analysis, and characterization of risks
Provides consistent framework for risk assessment across agencies
-Research feeds into risk assessments
-Crucial data uncertainty drives research
-New research findings modify risk assessment
Often, extrapolations must go beyond observations of actual effects and reflect different tolerances for risks – this generates controversy!
what are SARS
structure and activity relationships
life time rodent bioassays can be expensive and long
SARs can provide an alternative
Can be used for complex mixtures
Difficult to predict activity across chemical classes and multiple toxic endpoints
Often computerized programs which utilize databases of known toxicological effects
what are in vitro and short term tests
bacterial mutaiton assay
Transgenic knockout mice
- the ability of a substnace to hinder the growth of bacteria
- If the growth is present in the bacteria treated with itm it maens something is altering DNA, which is a possible cancer risk