Environmental Toxicology

Question 1

Acute vs Chronic Toxicity

Answer 1

single and often large dose of chemical vs. repeated exposure of small doses of a chemical over a long period of time

Question 2

Particulate matter (air pollutant)

Answer 2

mixture of tiny solid or liquid particles (e.g. biological matter)

Question 3

Gaseous air pollutant

Answer 3

CO and CO2, NO and SO, HS, O3

Question 4

Organochlorine Insecticides (DDT)

Answer 4

work by increasing the sensitivity of neurons, resulting in increased CNS stimulation that manifests as tremors and convulsions (and leads to death); have been largely phased out

Question 5

Organophosphorus Insecticides

Answer 5

initially developed as chemical warfare agent; requires metabolic activation to work in insects and break down in the environment so have a small impact on it; inhibits acetylcholinesterase causing Ach buildup

Question 6

Agent Orange (herbicide)

Answer 6

mimics plant growth hormones and causes uncontrolled and unsustainable growth leading to death; TCDD binds to aryl hydrocarbon receptor that results in chloracne, impairment of liver and CNS and some cancers and birth defects

Question 7

Lead exposure sources

Answer 7

old paint, lead-acid car battery, industries, jet fuel

Question 8

Effects of lead toxicity

Answer 8

CNS- decreased appetite, fatigue, irritability and can lead to encephalopathy, degradation of motor nerves, kidney dysfunction, anemia; treated with chelating agent like EDTA

Question 9

Mercury Exposure sources

Answer 9

in chlorine and NaOH production (air as vapour), ingestion of fish from mercury contaminated water (bioaccumulation)

Question 10

Effects of mercury toxicity

Answer 10

15% of mercuric mercury from vapours gets absorbed and accumulates in the kidneys, 90% of methyl mercury in fish and bacteria in water gets absorbed and targets the CNS causing nerve cell death and results in irritability, tingling, numbness, tremor, paralysis, vision and hearing loss; can be treated w charcoal

Question 11

Bisphenol A (BPA)

Answer 11

minute quantities of BPA can leach out of containers and into water and food; has estrogen-like activity and can play a role in reproductive cancers and fertility issues; greater risk in infants

Question 12

How do pharmaceuticals enter the environment?

Answer 12

antibiotics used in agriculture, antibiotics to treat pets, inappropriate disposal of unused medications, antibiotics used in aquaculture, human prescription drugs as a portion of excreted drug remains unchanged, discharge from manufacturing plants

Question 13

Neuroactive Drugs (in environment)

Answer 13

antiepileptics, antidepressants and antipsychotics; not effectively removed from water and have minimal exposure for humans but can have deleterious effects on fish

Question 14

Steroid Hormones (in environment)

Answer 14

those of most concern are estrogens that are found in low concentrations but can cause endocrine disruption in humans and can affect the reproductive capacity and sexual maturation of aquatic animals

Question 15

Antibiotics (in environment)

Answer 15

use of antibiotics in agriculture an lead to development of resistant strains, and bioaccumulation in plants can animals can lead to low-level exposure in humans

Question 16

Antihypertensive Drugs (in environment)

Answer 16

found in surface water and found in seafood but unknown whether bioaccumulation occurs

Question 17

Analgesics and Anti-inflammatories (in environment)

Answer 17

those found in drinking water do not pose a risk to human health and toxicities in aquatic species is minimal

Question 18

Initiation of carcinogenesis

Answer 18

procarcinogen activated by drug metabolizing enzymes and become ultimate carcinogens that damage DNA and can become cancerous if DNA is not repaired properly and a mutation occurs

Question 19

Promotion of carcinogenesis

Answer 19

proliferation of initiated cells mediated by tumour promoters

Question 20

Progression of carcinogenesis

Answer 20

rapid growth of tumours once established, increasing the malignancy of the tumour

Question 21

Cancer Prevention

Answer 21

avoid excess sunlight exposure, moderate alcohol intake, eliminate tobacco products, eat healthy, improve exercise habits, get vaccinated

Question 22

Goals of Cancer Treatment

Answer 22

prevent the cancer, cure the cancer (Hodgkin’s and childhood leukemia), control the cancer, relieve symptoms

Question 23

Alkylating Agents (Chemotherapeutic)

Answer 23

bind to and interfere w DNA replication

Question 24

Mitotic Inhibitors (Chemotherapeutic)

Answer 24

affect microtubule and spindle formation that prevents cell division

Question 25

Hormones and Hormone Antagonists (Chemotherapeutic)

Answer 25

treats hormone sensitive tumours by suppressing cell division

Question 26

Biologicals (Chemotherapeutic)

Answer 26

inhibit cell replication by blocking cytokines that normally control cell growth