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PHP 1700 Lecture 2

PHP 1700 Lecture 2

memorize.aimemorize.ai (lvl 286)
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29 cards
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Section 1

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Chemical Hazards

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Last updated

7 years ago

Date created

Mar 1, 2020

Cards (29)

Section 1

(29 cards)

Chemical Hazards

Front

TSCA (Toxic Substances Control Act) of 1976- assess new chemicals before enter marketplace and review chemicals on market (EPA) - some many have already sneaked by Lautenberg Chem Safety Act (2010- mentioned earlier for chlorine) - conduct reviews of chemical commerce- must condeuct a risk based interview before allowing hcemings enter the market

Back

Dose-Response Relationship

Front

type of correlative relationship betw. characterisitics of exposure to chemcial and spectrum of effects caused by chemical

Back

important end pts in risk assessments

Front

NOAEL: no observed adverse effect level LOAEL- lowest observed adverse effect level

Back

How Measure toxicity

Front

LD 50 - lethat dose that kills 50% of study population - dosage measured in weight of toxicant per body weight of subject- mg/kg of body weight Drug Action by ED 50 -- effective dose that produces desired effect on 50% of population

Back

Fungicide

Front

Back

Dose- Response Curve

Front

type of graph - used to describe the effect of exposure to chem or toxic substance upon organism as an environmental animal 2 types- one for indiv and one for population Note that from bottom slight effect to death- difference betw. linear and threshold Variation betw. 2 diff species - time course of dose adminstration

Back

Animal Study

Front

exposure to dose- severity spikes then decrease Problem- not simulate real world, specific ex, gives some idea for future studies, high dose needed to extrapolate

Back

Chemical Production

Front

increase over the yrs- 15 fold 3% increase China and EU contribute most China fully in selling Xenobiotics (foreign chemicals) - most "other" chemicals 70,000

Back

Insecticide

Front

Che-Inhibitors - basically stops acetylcholine esterase from working/inhibiting signal from Ach at synapse on muscle or neuron so keep stimulating Treatment: atropine- antagonize effect of Ach on receptors - used as treamtnet for OP and carbamate

Back

Acute Toxicity

Front

from single exposure ot toxicant- posioning, usually life threatening, diagnosed and treatments or antidotes

Back

Xenobiotics

Front

chemical substances foreign to bio system (incl. natural occuring subs, drugs, etc.)

Back

Toxicology

Front

study of adverse effects of chemical, physical, biological agents on living organisms, ecosystem, including prevention of amelioration of such effects Goal: understand causal relationshup betw. toxicant exposure and adverse human health effect Experimental Methods- highly controlled experiments usually in lab setting- typically using animals Epidemiological Methods- observations on uncontrolled populations, usually in environment setting

Back

Pesticide

Front

substance/mix with intent of preventing/destroying any pest-- also used for plant regulation, defoliant, or desicant six categories Insecticide Herbicide Fungicide Nematodicide Rodenticide Fumigant Organophosphates -organic esters of phosphoric acid Carbamates- salts or esters of carbamic acid Organochlorines - chlorinated hydrocarbon-based Herbicides/Defoliants - mixed structure; often hormone derived

Back

Subacute/Chronic Toxicity-

Front

prolonged exposure to toxicant - no immediate effect but could be life-threatening organ system effects/cancer - usually diff to diagnose and treat difficult to distinguish effects from other influences

Back

Risk Assessment Paradigm

Front

Hazard assessment- animal studies exposure assessment- field studies risk assessment- hazard x exposure- extrapolation to humans, safety factors risk management- depends on contect, risk-benefit analysis

Back

Herbicides and Defoliants

Front

Agent Orange (dioxins) Paraquat- dipyridyl compounds - GI edema, ulcers, acute tubular necrosis Atrazine Distinctly different compounds with different mechanisms and poorly described chronic toxicity- multiple modes of action either through cell division, biosynthesis, lipid synthesis Glyphosate (Roundup, Glyfonox) Very irritating to mucous membranes Low toxicity orally Not well absorbed dermally Works by inhibiting 5-enolpyruyl shikimate-3-phosphate synthesis (EPSPS), inhibiting amino acid production. EPSPS is not found in humans/animals. Triazines (atrazine, simazine) Most are irritating Low acute toxicity May be associated with some cancers, endocrine disruption

Back

Acute pOsioning

Front

25 mill

Back

Organochlorines

Front

DTT, lindane, cyclodienes alter ion permeabilities of nerve membranes nerve cells of insects hold open the molecule channels for sodium ions uncontrolled firing of the nerves kill the insects side effect- build up of DDT in birds cause disruption of Ca++ channels

Back

Routes of Absorption, Sistribution, Excretion

Front

Ingestion--GI (liver and bio)-- feces Inhalation-- Lung - then to GI- Intravenous/Dermal -- Blood Lymph-- Urine and expired Air

Back

Dioxin

Front

two benzene rings low solubility in H2O Very low vapor pressure Highly soluble in oils/fats Bind tightly to soil Very high chemical stability Very high biological stability Half-life is ~7 years in human body Therefore, dioxins are persistent organic pollutants that bioaccumulate and biomagnify in the food chain

Back

Joint Interaction of Chemical Mixtures

Front

most difficult yet bc all sorts of things in mix - antagonism- response less than expected - additivity- response as expected - dose (exposure) -repsonse (effect) - synergism- response greater than expected -- cosynergism- two agents enhance toxicity of each other -- potentiation- only one agent affects toxicity of other with no toxicity itself -- Coalitive- two agents with no observable toxicity cause a toxic effect Ways to use understanding of toxicity- phsyiological antagonims, chemical antagonism (chelating) , disposition antagonism, receptor antagonism Graph on agonist with competitive antagonist- going to left and agonist with irreversible antagonist- going down summation vs. synergism

Back

Toxicant

Front

toxic substances that are made!

Back

Toxin

Front

toxic substance made by living organism

Back

Polcychlorinated biphenyls

Front

PCB is an abbreviation for polychlorinated biphenyls. They are mixtures of up to 209 individual chlorinated compounds known as congeners. These compounds have no odor and range from colorless to light yellow. Some PCBs can exist as a vapor in air. PCBs can enter the air, water and soil during their manufacture, use and disposal as well as from accidental leaks and spills during their transport. carcinogens- biomagnify suppressed immune response reproductive effects - decreased birth weight neurological and endocrine effects

Back

Exposure-Disease Paradigm

Front

exposure--internal dose- target tissue dose- early bio effects-- altered structure fxn-- disease

Back

Insecticide: pyrethrins and pyrethoids

Front

Pyrethrins Natural insecticidal extract (keeps sodium channels open) Unstable - seizure, asthma, skin Pyrethroids Synthetic derivatives Used with piperonyl butoxide (microsomal enzyme inhibitor) - increased use- flea control

Back

Epi Study

Front

Observed- looking to see cause Problems- hard to prove cause, need good exposure info, health info, hard to learn about mechanism

Back

Chemical Hazards

Front

1. PPE use 2. admin contros 3. engineering controls 4. chem substitutions, 5. elimination (most preferred)

Back

Carbamates

Front

from calabar bean in WEst africa- derive fro mcarbamic acids- derivs of phsophoric acid - one of most popular in insecticide

Back