Toxins and Contaminants

Question 1

Define a contaminant.

Answer 1

It is a chemical or a chemical, which present at a concentration, that will cause harm to humans or the environment and are usually caused by humans.

Question 2

What is the problem at the moment?

Answer 2

1) There are 7 million recognised chemicals that are in existence.
2) 80,000 of them are in common use worldwide.
3) Toxicity Rarely Understood
4) Contamination is global

Question 3

How to can we eliminate all contaminants?

Answer 3

It is impossible to eliminate all contaminants we need a risk based decision making process and there are a plethora of legal instruments for doing this which involve source, pathway and receptor (human, ecological or physical).

Question 4

How do we look at risks in people or in animals?

Answer 4

It is through the NOEL (No effect level).

Question 5

What does LOEL stand for?

Answer 5

Lowest effect level.

Question 6

What is EC 50?

Answer 6

Effect concentration 50 and it affects half the test population.

Question 7

Sketch the dose response curve labelling all the features.

Answer 7

See notes.

Question 8

What are the 4 key factors in a risk assessment?

Answer 8

1) Hazard identification
2) Hazard assessment
3) Risk elimination
4) Risk evaluation

Question 9

What is contamination central to?

Answer 9

Sustainability in which there is a strict regulation.

Question 10

Name 4 historic areas where there was mass pollution.

Answer 10

1) Romans
2) 19th century industrialisation
3) 20th century chemical industry
4) 21st century pharmaceuticals

Question 11

Define a contaminated land.

Answer 11

It is land which contains substances that, when present in sufficient quantity or concentrations, are likely to cause harm directly or indirectly to humans, the environment or other targets such as construction materials.

Question 12

What doe contaminated land lead to?

Answer 12

Contaminated groundwater.

Question 13

What is important about the construction of landfill?

Answer 13

That is done correctly, otherwise you would have contaminated groundwater.

Question 14

Give two example where groundwater may be contaminated.

Answer 14

1) Leaking petrol storage tanks

2) Dry cleaners- Tetrachlorethene, people said just let it evaporate away however it is very dense.

Question 15

What mean contaminated groundwater will get worse?

Answer 15

Plumes- vertical body of a fluid moving through another.

Question 16

Define a micro-pollutant.

Answer 16

chemicals that have a serious ecological effect at low physical concentrations.

Question 17

State an important micro-pollutant.

Answer 17

The human contraceptive pill: occurs in ng concentrations, shown to be the major cause of widespread feminisation of fish and other marine animals.

Question 18

What ends up in wastewater?

Answer 18

Anything we take into our bodies will appear in wastewater for example if you take cocaine there will be a proportion of mg 100p^-1 day going into the wastewater contaminating it.

Question 19

What are the two classes of contaminants?

Answer 19

1) Organic pollutant- carbon based, often combined with chlorine, with organic pollutant structure is everything, PAH benzo pyrene carcinogenic by pyrene is not carcinogenic.
2) Inorganic pollutant- are things found naturally but because of human production of goods have been altered to drastically increase the amount of them in the environment.

Question 20

State 7 inorganic pollutants starting from ones which disrupt the ecosystem to ones which disrupt metabolism.

Answer 20

1) Carbon dioxide
2) Salnification
3) Oxides of N and S- accidfication
4) Eutrophication
5) Acid mine waters
6) Radioactivity
7) “Heavy metal” contamination

Question 21

Define bioaccumulation.

Answer 21

It is the gradual accumulation of substances, such as pesticides, or other chemicals in an organism.

Question 22

Do all chemicals degrade?

Answer 22

No

Question 23

Name a chemical that doesn’t degrade?

Answer 23

DDT

Question 24

What is DDT?

Answer 24

Semi-volatile organochlorinated compounds.

Question 25

What does DDT stand for?

Answer 25

Dichloride, diphenyl trichloroethane

Question 26

Name another semi-volatile organochlorinated compound other than DDT.

Answer 26

PCB (Poly chlorinated biphenyls)

Question 27

What is PCB used as?

Answer 27

An insulating material.

Question 28

State 5 characteristics of PCB.

Answer 28

1) Stable
2) Light insulators for electrical uses
3) Heat exchanges
4) Paints
5) plastics

Question 29

Why were PCB and DDT banned?

Answer 29

1) Seal fertility dropped drastically due to DDT and PCB found.
2) Eagles shown to bioaccumulate and bio-magnify DDT
3) Harmful to humans- Japan 1968 contaminated rice oil 1800 people poisoned.

Question 30

Describe the mine drainage process.

Answer 30

1) Coal was mined
2) Water table is lowered
3) Iron sulphides in coal
4) Oxidised and soluble
5) Pumps switch off
6) Water raises
7) Iron washed out
8) Hits the air

Question 31

State a macronutrient.

Answer 31

Magnesium

Question 32

State a micronutrient.

Answer 32

1) Copper
2) Zinc
3) Nickel

Question 33

What is the relationship between health effects and concentration of micro and macro nutrients?

Answer 33

If you don’y have any or very little concentration you will become ill, if you have small amount you become more healthy and if you have a large amount you become sick.

Question 34

Sketch the two graphs for micro and macro nutrients, health effects against concentration.

Answer 34

See notes

Question 35

Why is it incorrect when people refer non-essential elements as toxic elements?

Answer 35

Because toxicity is only observed at concentrations above a tolerance threshold.

Question 36

State 5 characteristics of Cadmium.

Answer 36

1) It has a low crustal concentration
2) Industrial uses such as plating and anti-corrosive coatings.
3) Stabiliser in PVC- 12%
4) In batteries (rechargeable)- 37%
5) Alloys- 4%

Question 37

State 5 health effect due to Cadmium.

Answer 37

1) If ingested, Cd is transported to all parts of the body by the bloodstream.
2) Kidney damage.
3) Disorders of calcium metabolism, softening of bones and osteoporosis.
4) High blood pressure and damage to red blood cells.
5) Destruction of testicular tissue.