Module 6

Question 1

What is an environmental toxicant?

Answer 1

A chemical released into the environment that produces adverse health effects in living organisms.

Question 2

Types of environmental toxicants?

Answer 2

Natural (volcanoes, mercury in fish) & Anthropogenic/man-made (industry, vehicles, pesticides).

Question 3

Acute vs Chronic toxicity difference?

Answer 3

Acute = one large exposure (chemical spill) → immediate harm.
Chronic = repeated small exposure over time → long-term damage (cancer).

Question 4

Why is Aflatoxin B1 important?

Answer 4

Shows acute toxicity (liver necrosis) vs chronic toxicity (liver cancer) → chronic ≠ severe acute.

Question 5

What are the 3 major environmental toxicants?

Answer 5

Air pollution, tobacco smoke, pesticides.

Question 6

Main types of air pollutants?

Answer 6

Particulate matter & gaseous pollutants (CO, CO₂, NOx, ozone, SOx).

Question 7

Major sources of air pollution?

Answer 7

Natural (volcanoes, forest fires) & anthropogenic (fossil fuel power, cars, industry).

Question 8

Main health effect of air pollution?

Answer 8

Respiratory tract irritation & inflammation.

Question 9

Who is most vulnerable to air pollution?

Answer 9

Children, elderly, asthma/heart disease patients.

Question 10

What is secondhand smoke made of?

Answer 10

Mainstream (exhaled) + sidestream (burning cigarette).

Question 11

WHO conclusion about secondhand smoke in 2002?

Answer 11

causes lung cancer & risk similar to direct smoking.

Question 12

Two main classes of pesticides?

Answer 12

Insecticides & herbicides.

Question 13

Organochlorines mechanism & example?

Answer 13

↑ neuronal sensitivity → CNS stimulation (convulsions). Example: DDT.

Question 14

Why was DDT banned?

Answer 14

Bioaccumulation, environmental persistence, insect resistance, wildlife decline.

Question 15

Organophosphorus insecticides mechanism example?

Answer 15

Irreversible AChE inhibition → ↑ ACh → overstimulation. Example: Malathion.

Question 16

What is Agent Orange contaminated with?

Answer 16

TCDD

Question 17

Organophosphate poisoning symptoms?

Answer 17

Low HR, incontinence, respiratory failure (cause of death).

Question 18

Effects of TCDD?

Answer 18

Chloracne, liver/CNS damage, ↑ some cancers.

Question 19

Paraquat toxicity?

Answer 19

Ingesting → burns, lung fibrosis, 2 tsp can kill.

Question 20

Sources of lead exposure?

Answer 20

Old paint, batteries, historical gasoline.

Question 21

Why are children more vulnerable to lead?

Answer 21

Absorb more lead than adults.

Question 22

Effects of lead?

Answer 22

CNS damage (kids), kidney damage, anemia, fatigue, irritability.

Question 23

Major exposure form of mercury?

Answer 23

Methylmercury from contaminated fish.

Question 23

Lead treatment?

Answer 23

Chelating agents.

Question 24

Difference between mercury forms?

Answer 24

Mercuric (inhaled → kidney damage), Methylmercury (fat-soluble, most toxic → brain damage)

Question 24

Minamata disease cause?

Answer 24

Methylmercury in wastewater.

Question 25

What is BPA used for & concern?

Answer 25

Plastics/linings; estrogen-like activity.

Question 26

Is BPA safe for the general population?

Answer 26

Yes at normal levels (but banned in baby bottles).

Question 26

Where are pharmaceuticals found now?

Answer 26

Water, soil, animals.

Question 27

How do pharmaceuticals enter environment?

Answer 27

Agriculture, improper disposal, aquaculture, human excretion, factories.

Question 28

Major risk of anticancer drugs in water?

Answer 28

Toxic even at low doses.

Question 28

Main classes of pharmaceuticals in environment?

Answer 28

Neuroactives, steroid hormones, antibiotics, antihypertensives, analgesics.

Question 28

Environmental effect of neuroactive drugs?

Answer 28

Affect fish reproduction (low human risk).

Question 29

Concern with steroid hormones?

Answer 29

Endocrine disruption in aquatic species.

Question 30

Why are antibiotics concerning environmentally?

Answer 30

Antibiotic resistance.

Question 31

Prevention strategies for pharmaceutical pollution?

Answer 31

Take-back programs, better sewage treatment, regulation, toxicity testing.

Question 32

What % of Canadians get cancer?

Answer 32

45% men, 43% women.

Question 33

Key properties of cancer cells?

Answer 33

Unlimited division, invasion, metastasis.

Question 34

Risk-increasing diet factors?

Answer 34

Red meat & high salt.

Question 34

Most common cancers?

Answer 34

Lung, breast, colorectal, prostate.

Question 35

Two causes of cancer?

Answer 35

Genetic + environmental.

Question 36

Top preventable cause of cancer?

Answer 36

Tobacco

Question 37

Protective diet components?

Answer 37

Fruits & vegetables.

Question 38

Examples of occupational carcinogens?

Answer 38

Asbestos, benzene, formaldehyde, radiation.

Question 39

Infection-linked cancers?

Answer 39

HPV→cervical, Hep B/C→liver, H.pylori→stomach.

Question 39

Cancer prevention strategies?

Answer 39

No smoking, sunscreen, reduce alcohol, good diet, exercise, vaccines.

Question 40

Goal of chemotherapy?

Answer 40

Target and kill rapidly dividing cells.

Question 41

4 classes of chemotherapeutic drugs?

Answer 41

Alkylating agents (DNA damage) Mitotic inhibitors (block division) Hormones (block hormone-sensitive tumours) Biologics (block cytokines/signals)

Question 42

Side effects arise because...?

Answer 42

Healthy fast-dividing cells also harmed (GI, hair, bone marrow).

Question 43

Why use combination therapy?

Answer 43

Prevent resistance + reduce toxicity per drug.