Environmental toxicology: Guest Lecturer

Question 1

Why are toxic metals useful in the industry?

Answer 1

-density
-malleable
-absorb vibration
resistent to corrosion

Question 2

How is lead and cadmium absorbed in the body?

Answer 2

-little via skin
-some via inhalation
-majority via ingestion

Question 3

What factors increase the absorption of toxic metals in the gut?

Answer 3

-young age
-empty stomach
-Ca, Zn or Fe deficiencies

Question 4

What is the “acceptable” level of lead and cadmium in water?

Answer 4

5ug/L

Question 5

How does lead/cadmium enter our food?

Answer 5

-mostly through the soil that is used to grow food

Question 6

What is the estimated intake of lead of Canadians per day?

Answer 6

-100ng/kg/day

Question 7

What does ALARA stand for?

Answer 7

as low as reasonably achievable
-means there is no known safe level of exposure

Question 8

What is the purpose of the divalent metal transporter 1?

Answer 8

-increases absorption of lead/cadmium
-deficient ppl have an increased expression of it

Question 9

What is the mechanism of lead/cadmium?

Answer 9

-enters cells via passive diffusion or metal transport proteins
-toxic metals compete with essential metals

Question 10

What is the major reservoir of lead in the body? How is it released?

Answer 10

-bones
-gradual release can cause long term expxosure
-pregnancy, osteoporosis, hyperthyroidism can increase release
-can be transferred from mother to fetus and through breastfeeding

Question 11

What is the half-life of bones?

Answer 11

15-25 years

Question 12

What does lead target in the body?

Answer 12

-proteins that naturally bind calcium or zinc
-ex. Ca binds to syn 1 in brain = lead can bind to it and disrupt neurotransmission = cog impairment
-aminolevulinic acid dehydratase binds to zinc = lead can bind and prevent hemoglobin synth = anemia

Question 13

How does cadmium interfere with the body?

Answer 13

-stored in liver and kidney
-affects cell proliferation and apoptosis
-generates reactive O2 species
-interfere with DNA repair
-associated with cancer, osteoporosis, kidney disease

Question 14

What is asbestos?

Answer 14

-naturally occurring fiber mineral
-previously used in construction as an insulator and fire resistance
-also found in cig filters, vinyl flooring etc.

Question 15

Who can get metal toxicity treatment?

Answer 15

-only people who know they had exposure and the levels were enough to be a health issue

Question 16

What are some types of asbestos?

Answer 16

-chrysotile
-amosite
-tremolite

Question 17

How does asbestos affect our bodies?

Answer 17

-inhalation of fibers
-carried deep into the lungs
-can’t be broken down or cleared -> inflammation -> scar tissue = asbestosis
-scarring -> decr. gas exchange -> shortness of breath

Question 18

What are some characteristics of asbestosis?

Answer 18

-onset within 10-40 years after significant exposure
-may cause lung cancer, mesothelioma, heart disease
-only prevention is no exposure

Question 19

When was asbestos declared a carcinogen and when did countries ban it?

Answer 19

-WHO declared carcinogen in 1987
-Canada banned in 2018
-US banned one type in 2024

Question 20

What is mycosis?

Answer 20

-invasive mold infection
-superficial, subcutaneous, systemic

Question 21

What are the toxins in mold?

Answer 21

-mycotoxins: metabolites produced by fungi
-produced by certain species (not including black moulds inside)

Question 22

What is the route of exposure for mycotoxins?

Answer 22

-ingestion, inhalation, skin absorption

Question 23

What is aflatoxin B1?

Answer 23

-heatocarcinogen
-introduces mutations at tumor suppressing genes
-found in peanuts, spices and corn