Environmental toxicology: Guest Lecturer Flashcards
Why are toxic metals useful in the industry?
-density
-malleable
-absorb vibration
resistent to corrosion
How is lead and cadmium absorbed in the body?
-little via skin
-some via inhalation
-majority via ingestion
What factors increase the absorption of toxic metals in the gut?
-young age
-empty stomach
-Ca, Zn or Fe deficiencies
What is the “acceptable” level of lead and cadmium in water?
5ug/L
How does lead/cadmium enter our food?
-mostly through the soil that is used to grow food
What is the estimated intake of lead of Canadians per day?
-100ng/kg/day
What does ALARA stand for?
as low as reasonably achievable
-means there is no known safe level of exposure
What is the purpose of the divalent metal transporter 1?
-increases absorption of lead/cadmium
-deficient ppl have an increased expression of it
What is the mechanism of lead/cadmium?
-enters cells via passive diffusion or metal transport proteins
-toxic metals compete with essential metals
What is the major reservoir of lead in the body? How is it released?
-bones
-gradual release can cause long term expxosure
-pregnancy, osteoporosis, hyperthyroidism can increase release
-can be transferred from mother to fetus and through breastfeeding
What is the half-life of bones?
15-25 years
What does lead target in the body?
-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
How does cadmium interfere with the body?
-stored in liver and kidney
-affects cell proliferation and apoptosis
-generates reactive O2 species
-interfere with DNA repair
-associated with cancer, osteoporosis, kidney disease
What is asbestos?
-naturally occurring fiber mineral
-previously used in construction as an insulator and fire resistance
-also found in cig filters, vinyl flooring etc.
Who can get metal toxicity treatment?
-only people who know they had exposure and the levels were enough to be a health issue
What are some types of asbestos?
-chrysotile
-amosite
-tremolite
How does asbestos affect our bodies?
-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
What are some characteristics of asbestosis?
-onset within 10-40 years after significant exposure
-may cause lung cancer, mesothelioma, heart disease
-only prevention is no exposure
When was asbestos declared a carcinogen and when did countries ban it?
-WHO declared carcinogen in 1987
-Canada banned in 2018
-US banned one type in 2024
What is mycosis?
-invasive mold infection
-superficial, subcutaneous, systemic
What are the toxins in mold?
-mycotoxins: metabolites produced by fungi
-produced by certain species (not including black moulds inside)
What is the route of exposure for mycotoxins?
-ingestion, inhalation, skin absorption
What is aflatoxin B1?
-heatocarcinogen
-introduces mutations at tumor suppressing genes
-found in peanuts, spices and corn
