Topic 3: Part H

Question 1

Heavy Metals

Answer 1

1. lead
2. cadmium
3. selenium
4. arsenic
5. mercury

Question 2

environmental contaminants/pollutants

Answer 2

• this includes industrial pollutants, toxic metals and contaminants from packaging
• routine monitoring of chemical contaminants is carried out and a ban is imposed if levels are too high

Question 3

Mercury

Answer 3

• a naturally occurring element in soils and rocks, lakes, streams and oceans

Question 4

how is mercury released into the environment?

Answer 4

• human activities: pulp and paper processing, mining operations, and burning of garbage and fossil fuels

Question 5

is mercy dangerous

Answer 5

high amounts of mercury can damage the nervous system of people and animals

Question 6

Methylmercury

Answer 6

bacteria in water convert mercury into methyl mercury, which is a more toxic form
methyl mercury is water soluble and can remain within our body for extended periods of time
causes a lot of problems

Question 7

BBB and methylmercury

Answer 7

methyl mercury can cross the blood brain barrier, which makes it extra dangerous and contributes to diseases such as Alzheimer’s

Question 8

food chain and mercury

Answer 8

mercury tends to accumulate in the food chain so that predatory species have higher levels
this term is bioaccumulation or bioconcentration
- predators higher on the food chain have higher amounts of mercury in them

Question 9

CFIA guideline for mercury levels

Answer 9

the guideline for mercury is that 0.5-1 ppm in fish is NOT exceeded

Question 10

average level of mercury in fish in Canada

Answer 10

0.2 ppm, much lower than the permitted guideline

Question 11

fish that are very high in mercury

Answer 11

swordfish, king mackerel, shark, fresh and frozen tuna (albacore)
note = these fish are higher on the food chain

Question 12

fish or seafood lower in mercury

Answer 12

shrimp, canned tuna (skip jack), salmon, pollock, catfish

Question 13

labels of canned tuna

Answer 13

wild ALBACORE white tuna (more mercury)

flaked light tuna (less mercury)

Question 14

what should consumers limit their consumption of fresh/frozen tuna to?

Answer 14

150g per week (does not apply to canned light tuna)

Question 15

what should sick people, pregnant people, or children limit their consumption of fresh/frozen tuna to?

Answer 15

1 meal per month

Question 16

symptoms of chronic maternal fish consumption (exposure to methyl mercury)

Answer 16

• IQ deficits
• abnormal muscle tone
• reduced motor function
• lower attention and visuospatial performance
• increased blood pressure in children (hypertension)

Question 17

at what age can the neuropsychological effects of chronic maternal fish consumption symptoms be detected?

Answer 17

in children aged 7 years following prenatal exposure to methyl mercury

Question 18

Halogens and Organic Halogens

Answer 18

• chlorine
• iodine
• vinyl chloride
• ethylene dichloride
• trichlorenethylene
• dioxins
• polybrominated biphenyl (PBB)
• **polychlorinated biphenyls (PCB’s)

Question 19

PCB’s

Answer 19

• accumulate in the food chain
• cause fatigue, eye irritation, growth retardation when children are exposed prenatally
• man-made, not naturally occurring in the environment
• banned many years ago, but they persist in the environment. highly difficult to destroy
• very small levels cause averse health effects

Question 20

what are halogens and organic halogens often used as?

Answer 20

often used as disinfectants