Lecture 1: Introductory Toxicology Flashcards
________ is the study of the
adverse effects of chemical, physical or biological
agents on living organisms and ecosystems,
including the prevention and amelioration of such
adverse effects.
Toxicology
this is an example of a new(er) definition of toxicology!
what is the simpler definition of toxicology?
Toxicology is the study of the
harmful interactions between chemicals and biological systems.
T/F: ~80,000 chemicals registered in the USA alone
true!
around how many new chemicals are introduced each year?
~2000
why do we mainly study toxicology?
its super important for human health, and environmental health, which affects human health
T/F: Toxicology may very well be the oldest science
true! been around for thousands of years!
think medicinal plants and journals about poisons/toxicants!
T/F: We can detect many natural toxins by taste and smell
true!
plant alkaloid toxins taste “bitter”, so we stop eating those plants
what are two examples of ways we took toxicology and tried to make our lives better? (spoiler alert: one of them didn’t lol)
pesticides and flame retardants!
______: Formulated views that remain part of modern toxicology, pharmacology, and therapeutics
* Considered treating disease with chemicals
Figured out that dose is everything!
Paracelsus
(a.k.a. Philippus Aureolus Theophrastus Bombastus von Hohenheim, 1493-1591)
* German physician-alchemist
what are the four Paracelsus’ principles?
- One should make distinctions between therapeutic and toxic properties of chemicals
- Those properties are sometimes but not always distinguishable except by dose
- Experimentation is essential in the examination of responses to chemicals
- One can ascertain a degree of specificity of chemicals and their therapeutic or toxic effects
Paracelsus’ principles led to the notion of ______ relationships in toxicology
dose-response
when was the rise of the chemical industry?
20th century
The number of chemicals produced by industry exploded and many were
used without toxicity testing or environmental impact assessments (because these regulations were not always around…)
______: A synthetic insecticide developed in the 1940’s
DDT
what was DDT first developed to be used for? what was it widely used for afterwards
First used to prevent insect-borne human diseases (e.g., malaria)
* Then widely used to treat livestock, crops, gardens and in cities (e.g., mosquitoes in Winnipeg)
what two categories does DDT fall under since its so persistent in the environment?
Persistent Organic Pollutant (POPs)
Legacy Pollutant
DDT has long range transport in the upper atmosphere… why?
its super stable, so it gets deposited in the atmosphere… meaning everyone is exposed
Rachel Carson (1907-1964) is widely regarded as the inspiration of the environmental movement in the _______
1960s
who wrote Silent Spring? (1962)
One of the most important contributions to ecotoxicology, on the dangers of pesticides
Rachel Carson
what did Rachel Carson discuss in Silent Spring?
Discussed link between egg-shell thinning in
birds from industrially synthesized pesticides
what systematically chnaged because of Rachel Carson’s “Silent Spring”, on the dangers of pesticides
Spurred a national policy on pesticides in the
US and later led to ban on DDT (in 1972) and
other organochloride pesticides
T/F: Many industries used to simply dump waste chemicals into waterways
true! unfortunately
what is it called when companies dump chemical waste into waterways?
economic “externality”
(a cost or burden of production that is not paid for by the company, often paid by society)
The Cuyahoga River in ______ caught fire (for the 13th
time!) in 1969. This sparked national outrage, and helped lead to environmental legislation.
Cleveland, Ohio
what are Endocrine Disrupting Compounds (EDCs)?
Chemicals that can mimic or disrupt hormone
function (e.g., testosterone, estrogens, thyroid
hormones)
T/F: Vast majority of EDCs mimic estrogen in the body
* e.g., Bisphenol A (BPA) and Bisphenol S (BPS)
true
why are we so concerned about BPA’s and BPS’
Concern about the feminization of wildlife (e.g., fish, alligators) and possible links to sex-specific cancers
in humans (e.g., breast cancer)
what are the three categories that have received significant research since the 2000s
nanoparticles
pharmaceuticals and personal care products
microplastics
T/F: most of the knowledge of toxicology has become known only in the past 4-5 decades
TRUE!! often when looking into how to deal with one problem, several others are discovered within our research
______: a substance capable of producing a
toxic effect when in contact with a living organism
at a sufficiently high concentration
Toxicant
________: Substance that pollutes, spoils or poisons something, in the environment
contaminant
_____: a toxicant produced by a living organism (microbe, plant, or animal)
i.e a naturally produced toxicant
Toxin
_____: substance capable of causing malformation during the development of the fetus
Teratogen
e.g., Thalidomide in the late 50’s early 60’s
what was thalidomide prescribed as? what did it cause, since its a teratogen
was prescribed to pregnant women for morning sickness.
found to be a teratogen that causes phocomelia (limbs close to the trunk
or severely underdeveloped)
Dr. Frances Kelsey, a Canadian physician working
for the USA Food and Drug Agency (FDA),
prevented the licencing of thalidomide in the USA, what country authorized this drug based on the same info that the American authorities found to be insufficient?
Canadian Gov.
victims of thalidomide were compensated in May 2015
______: physical or chemical agents that change the genetic material,
usually DNA, of an organism and thus increases the frequency of mutations
above the natural background level
Mutagens
usually UV and radioactive substances
Benzopyrene is in tobacco smoke and can bind to DNA and form a _____. When repaired by the cell, a
different nucleotide base (mutation) can be
accidentally be inserted while trying to fix the DNA strand… making benzopyrene a mutagen!
DNA adduct
which is a segment of DNA that has been chemically modified by the covalent attachment of a substance, typically a carcinogenic or mutagenic chemical
A ______ is any substance, radionuclide, or
radiation that is an agent directly involved in causing
cancer
carcinogen
T/F: all mutagens are carcinogens
false! mutagens aren’t necessarily carcinogens, and
carcinogens aren’t necessarily mutagens!!!
______ (water loving): Dissolve in water, polar. Can
interact through hydrogen bonds with water molecules.
Hydrophilic
_______ (water hating): Do not dissolve in water, non-
polar. If ingested, will be stored in fat tissue, often called lipophilic.
Hydrophobic
T/F: toxicants are different sizes
true! they can be single atoms, small molecules, or even whole proteins!
Because these have vastly different properties due to their various size and chemical compositions, the way we have to detect and quantify toxicants can vary greatly!
______: substances foreign to life, Human-made substances that did not exist in nature
before being synthesized in the laboratory
Xenobiotics
what are the five types of common xenobiotics?
arenes
biphenyls
brominated fire retardants
persistent organic pollutants
legacy pollutants
T/F: arenes can be natural
true!
what is the simplest form of an arene?
benzene
More than 1 benzene ring together are called….
polycyclic aromatic hydrocarbons (PAHs)
what is the simplest form of a PAH
naphthalene
_____: three pairs of doubly bonded atoms (usually carbon) bonded together in a planar (flat) hexagon
arenes
_____: 2 benzene rings attached
biphenyls
When chlorines are attached to biphenyls you get…
polychlorinated biphenyls (PCBs)
When bromines are attached to biphenyls you get…
polybrominated biphenyls (PBBs)
______: are in things like plastics, textiles, electronic castings, circuitry… and have now been banned
polybrominated diphenyl ethers (PBDEs)
______: Extremely stable in the environment
* Often lipophilic
* May still be in use today
persistent organic pollutants (POPs)
_____: Very persistent in the environment, but their use has been banned.
* Still show up in nature and in wild animals
legacy pollutants
Toxicologists and environmental chemists (in North America…) often use the _______ system for measurement
‘parts per’
what is the measurement of “ppm”
1 mg/L
most common measurement
what is the measurement of “ppb”
1ug/L
1 g of substance in 1,000,000 L of water
what is the measurement of “ppt”
1 ng/L
1 g of substance in 1,000,000,000 L of water
T/F: Because of technology improvements, we can
measure compounds at trace concentrations.
* Even picograms (1 trillionth of a g) of a substance!
true!
what is mechanistic toxicology?
Focuses on understanding specific physiological,
biochemical and molecular mechanisms by which toxicants have their effects
what does an adverse outcome pathway describe?
if something will be dangerous to humans
what is descriptive toxicology?
Focuses on the toxicity testing of chemicals
Provides information for safety evaluation and regulatory requirements by using LC50s, bioassays/biomarkers, and animal testing
what is clinical toxicology?
Focuses on effects
(usually in humans)
caused by or uniquely
associated with toxicants
Usually a specialization of
medical doctors
what is forensic toxicology?
Focuses on the medical and
legal aspects of toxicants on
humans and animals, why did they die?
what is reproductive toxicology?
Studies the occurrence of adverse effects of
toxicant exposure on the male or female
reproductive system
T/F: Global amphibian populations are in decline. In part, due to xenobiotic toxicants affecting their reproduction
true
T/F: Over an 18 year span, the average sperm counts dropped by a third
in 26,000 human males
true!
what is developmental toxicology?
Studies life-long adverse effects of toxicants arising from exposures before conception, during prenatal development, and postnatal to puberty
what is occupational toxicology?
Focuses on toxicological hazards occurring in workplace, with
objective of preventing adverse effects in workers
In the 1770s, Percival Potts made the first occupational toxicology observation: what was it?
chimney sweeps had
higher incidences of cancer from exposure to soot
what is environmental toxicology?
Focuses on detecting compounds
and impacts in the natural
environment
what is ecotoxicology?
Impacts on animals and
populations in a natural ecosystem
what is the difference between environmental toxicology and ecotoxicology?
environmental: largely focuses on the compound
eco: largely focuses on the organismal response
what is regulatory toxicology?
Work focuses on the risk
decision-making based on data from mechanistic and descriptive toxicology
they set standards for “safe” exposure!
