quiz 4 study materials
Quantitative Structure-Activity Relationship (QSAR)
software that assigns expected toxicity values to each part of a molecule to determine toxicity of the the whole molecule; does not account for interaction of chemicals
Synergism
the effect of a combination of toxins is greater than would be expected from the sum of the toxins individually; sum of parts is greater than the whole
antagonism
the effect of a combination of toxins is less than would be expected from the sum of the toxins individually
Routes of exposure for toxins
gastrointestinal absorption
dermal absorption
Respiratory inhalation
What can be gastrointestinally absorbed?
asprin, ibuprofen, naproxen
major route for the absorption of nutrients and water into the body
What can be dermally absorbed?
solvents, pesticides, biocides, cosmetology products, metals, pharmaceuticals
7 Classifications of toxins
respiratory toxins
general metabolic toxins
neurotoxins
endocrine system toxins
allergens
carcinogens
mutagens
teratogens
Sulfur dioxide
type: respiratory toxin
description: respiratory tract irritant, damages lung tissue, increased airway resistance
Risks: long-term exposure to low levels leads to increased risk of health problems
also toxic to plants (early insecticide)
nitrogen dioxide
type: respiratory toxin
description: causes inflammation of lung tissue
Risks: may have long-term effects on ability to fight lung infections
bronchiolitis fibrosa obliterans; silo-fillerâs disease
dangerous to humans at high concentrations
ozone
type: respiratory toxin
description: pungent bluish gas; coughing; shortness of breath; nose and throat irritation; lungs produce fluid
causes plants to be more susceptible to diseases
allotropes
from of an element that differs from other forms of same element in its molecular arrangement
particulates
type: respiratory toxin
description: result of indoor and outdoor air pollutions such as dust, combustion, and smoke
silicosis; asbestosis; brown lung (cotton); farmerâs lung (hay mold); black lung (coal dust)
general metabolic toxins
interfere with some essential biochemical process
includes toxins with multiple modes of action
effects can be massive and immediate or slow and cumulative
carbon monoxide
carbon monoxide
type: general metabolic toxin
description: disrupts hemoglobin carrying oxygen in blood
nitrate
type: general metabolic toxin
description: converted to nitrite ions in the body, oxidizes Fe^2+ in hemoglobin to form methemoglobin
blue-baby syndrome
heavy metals
type: general metabolic toxin
description: react with sulfhydryl groups which can deactivate enzymes
mercury: most toxic in compounds; vapor is toxic when oxidized in body; in light up shoes; vapor and mercury compounds such as fungicides for grain
lead: causes brain, liver, and kidney damage; treatment involves chelating agents; exposure to lead as well as its compounds is unsafe
Cadmium: can replace calcium in bones; severe abdominal ain, vomitting, and diarrhea; 30 year half-life in body
arsenic
type: general metabolic compound
description: inactivates enzymes by binding with sulfhydryl groups
symptoms: vomiting, diarrhea, abdominal pain, esophageal pain, vasodilation, heart-rate depression
pesticides
substances that kill or otherwise control unwanted organisms
insecticides
pesticide to kill insects
herbicides
pesticides to kill palnts
fungicides
pesticides to control growth of fungi
DDT
organochlorine pesticide (insecticide)
no apparent effect on humans
controls mosquito-borne diseases
various species developed resistance
caused soft shells in eagles
eventually banned in the US
PCBs (polychlorinated biphenyls)
developed in 1930s as transformer insulator
little acute toxicity in humans
chronic toxicity possible but not proven
chloracne is definite symptom but not fatal
Dioxins
variety of polychlorinated benzodioxins commonly formed as byproducts in reactions involving chlorinated hydrocarbons
similar structure to PCBs
no known use
Agent orange in Vietnam war
severely toxic in small animals
TCDD poisoned Ukrainian presidential candidate
Neurotoxins
disturb the chemical processes occurring at the synapse during nerve signal transmission
most effect cholinergic nerves (things you donât think about) that use acetylcholine as neurotransmitter
inhibit synthesis of acetylcholine; block the receptor; or permanently turn on nerve
interfere with the Acetylcholine cycle
acetylcholinesterase poisons
type: neurotoxin
inhibit enzyme cholinesterase that breaks down acetylcholine
many widely used insecticides (very environmentally important)
can be ingested or absorbed through the skin
parathion, malathion
nerve gas sarin in WWII
one drop can kill person
Endocrine hormones
hormones in an organism that are produced by endocrine glands into bloodstream
eventually attach to receptors on certain cells in the body to produce a response
environmental estrogens
type: endocrine toxin
synthetic chemicals that can mimic naturally occuring estrogens
greatest effects in wildlife like fish
PCBs dioxins, pesticides, BPA(?)
feminization of males, disruption of reproduction, effects on fetal development
phytoestrogens
endocrine disruptor
in plants
implicated in some problems
found in soy
Allergens
large class of compounds that activate and overstimulate the immune system
ex: formaldehyde
carcinogens
cause cancer
uncontrolled cell growth
cells lose functional identity and locational restriction
seem to require repeat exposure
benzo(a)pyrene; 2-naphthylamine
not all are synthetic chemicals
mutagens
chemicals that damage or alter the genetic information in cells
closely related to carcinogens
of great concern when interfering with reproductive cycle
difficult to determine causes
benzo(a)pyrene; ozone
teratogens
induce birth defects by causing direct damage to a developing embryo
Cannot be classified as mutagens because they DO NOT act by disturbing genetic material in cells
of most concern during embryonic stage of pregnancy when critical organs are formed
alcohol, acutane, arsenic, lead, mercury, PCBs, thalidomide
Diethylstilbestrol (DES)
type: tereatogen
synthetic estrogen-like molecule that could be ised as natural estrogen substitute
used to suppress lactation
was used to decrease likelihood of miscarriages until female children began to develop clear cell adenocarcinoma CCA
persistents
toxins that do not break down in the environment
3 ways chemicals in the environment break down
hydrolysis
ultraviolet light
mircoorganisms
bioaccumulation
the accumulation of toxins in the fat of an organism that results from the organism coming into contact with water containing toxins
in ONE organism
biomagnification
the increase in the concentration of fat-soluble toxins as one moves to higher levels of the food web
concentrations of some toxins increase going up the food chain
catalysts
substances that speed up a reaction without being used up in the reaction
The author of the ground-breaking book, Silent Spring, which sounded an alarm concerning risks to the environment, was
Rachel Carson