EMA Lecture 9 Flashcards
What is a contaminant?
Substance released due to human activity
What is a pollutant (compared to contaminant)
A pollutant causes a biological effect
What is POP?
Persistent Organic Pollutants are chemical substances that are toxic, persist in environment for long periods of time, bioaccumulate in food chain, and cause health risk to humans and environment
What is an effect of toxins in the environment?
-Impact the physiology or behaviour of an organism and reduce growth, reproduction or survival
-Can indirectly reduce prey species
What are some everyday exposure routes of toxins?
Dermal exposure (skin)
Accumulation
Transfer (mother to child)
Oral exposure
Inhalation exposure
What are some anthropogenic sources of toxic pollutants
-Industrial effluent
-Oil spills
-Pesticide in agricultural runoff
-Sewage waste
-Hazardous waste
-Combustion
What is CAS
Registry of chemicals
How many chemicals are registered with CAS?
171 million unique organic and inorganic chemical substances
What does EU legislation require in relation to medicines for human or animal use?
-They must be subjected to an environmental risk assessment
-Only compulsory for new products since 30th October 2005
What questions are asked about new medicinal drugs in relation to the environment?
-How much of drug will enter the environment
-How will organisms be affected from exposure
-Is the environmental risk acceptable
What are the three exposure assessment rates at different spatial scales for PEC?
-Local
-Regional
-European
What does PEC stand for?
Predicted Environmental Concentration
What does PNEC stand for?
Predicted No-Effect Concentration
What is the acceptable risk concentration?
PEC/PNEC <1
What is an unacceptable risk concentration?
PEC/PNEC >1
What does ERA stand for?
European Research Area
What can information from an ERA be used for?
-Compare the relative environmental risk of different drugs
-Minimise the amount of medicinal product released into the environment
-Identify guidelines for proper use and disposal for consumers
What are some issues in risk assessments?
-Organisms are exposed to low levels over long periods of time - hard to replicate in lab
-Toxicity tests are acute tests, short
-More information is needed on chronic toxicity
What is an additive drug reaction?
Occurs when the combined effect of two drugs is equal to the sum of each drug being given alone
1 + 1 = 2
Name an example of additive drug interactions
Heparin and alcohol will increase bleeding
What is drug synergism?
Occurs when drugs interact with each other and produce an effect that is greater than the sum of their separate actions
1 + 1 = 3
What’s an example of synergism drug interaction
Nicotine and alcohol
What is an antagonistic drug reaction?
Occurs when one drug interferes with the action of another, causing neutralisation or a decrease in effect of the other drug
Why are pesticides used?
Public health, mosquitoes
How many species of Anopheles carry a protozoan parasite that causes malaria?
60 out 380
What is another use for pesticides?
Agriculture
What are the benefits of pesticide use in farming?
-Increased yields
-Chemical herbicides control weeds
-Rows of plants can be planted closer together
-Insecticides control pests instead of crop rotation
When was pesticides beginning to expand?
After 1945
Why does forestry use pesticides?
-Reduce damage done by insect pests
-Applied by aerial methods
What damage did the gypsy moth do in America in 1981?
Defoliation of 40,000 km 2
Why did pesticide use explode after 1945?
More widely available
Efforts to increase world food supply
What are the problems of indiscriminate use of pesticides?
-Non target species are killed
-Pests develop resistant
-Persistent in environment
-Food chain magnification
How are pesticides classified?
-Target species
-Chemical nature
-Mode or time of action
What are chlorinated organics?
Consist of Cl atoms attached to organic moieties
Stable and accumulate in lipid tissue
Biomagnification and food chain transfer
Highly toxic to fish and birds
What does DDT stand for?
dichloro-diphenyl-trichloroethane
What chemical group does DDT belong to
Organochlorines (OCs) or chlorinated hydrocarbons
What is the chemical structure of DDT like?
Has at least one covalently bonded atom of chlorine that has effect on the chemical behaviour
What are some other examples of OCs?
PCBs
Aldrin
Mirex
Toxaphone
All are banned or restricted
When was the insecticidal properties of DDT discovered and by whom
1939 by Swiss chemist Paul Muller
What was peak production of DDT?
US - 82,000 tons in 1963
When was DDT banned in the US for agricultural use?
1972
How does DDT kill?
It is a nerve toxin
-Interferes with neurotransmission
Not species specific
Can persist in environment
Can kill months later
Why is DDT so harmful to the environment?
-Slow to break down, can be in environment for years
-Not water soluble
-Bioaccumulate and are stored in fat tissue
How long is the soil life of DDT
50% remains in soil for 2-15 years
How long is the half life of DDT in the aquatic environment?
Over 150 years
What does lipophilic mean?
Soluble in fat, oils and lipids
What does bioaccumulation mean?
Accumulate in fat cells of animals
What is biomagnification?
When something passes through food chains
Top predators are exposed to high doses
What can be the effects of toxins on insects?
Death
What is the effect of toxins of fish?
Reproductive effects
Neurotoxin effects
What is the effects of toxins on birds?
Eggshell thinning
What is the effects of toxins on mammals?
Liver and kidney damage
Neurotoxin effects
Teratogenic effects (mice)
Carcinogenic effects likely
What is a metabolite of DDT?
DDE
What does DDE stand?
Dichlorodiphenyl dichloroethene
Why is DDE a problem?
Produced slowly by degradation in environment
Fat soluble and mimics the action of estradiol and causes decline in androgen synthesis
How is DDE harmful to birds?
Causing egg shell thinning
- Caused declines of peregrine falcon, brown pelican, bald eagle and Californian condor
What are organophosphates?
Consists of one or more phosphate groups attached to an organic moiety
When were organophosphates first marketed?
1944
What is DDT still use for today?
-Control of disease carrying organisms in parts of the world
-2007 COP in Stockholm concluded it still needed to be used to control disease vectors
What does Cd stand for?
Cadmium
What does Hg stand for?
Mercury
What does HCB stand for?
Hexachlorobenzene
What does PCB stand for?
Polychlorinated biphenyls
How much Persistent organic pollutants need to be eliminated?
14 million tonnes
