Water Pollution Flashcards
Describe the development of the fields of ecotoxicology and risk assessment beginning in the 20th century. What were the important classes of chemicals, when were they recognized as potential problems, and what was done in response to this pollution.
Began before WWII:
- Introduction of DDT: Discovered in 1890s; Insecticidal properties discovered by Paul Muller in 1939; patented in 1942; used to control typhus and malaria during WWII. After war, used for agriculture, Dutch Elm Disease, malaria
- Other Organochlorine Insecticides
- Development of Nerve Gases
1980s - Rachel Carson and Theo Colborn wrote books criticizing the unchecked growth in chemical usage.
Risk Assessment procedures put in place. In 1990s and 2000s, EPA began mandating tthat testing be done on certain chemicals
How many chemicals are used in industrialized societies today? What is known about the toxicity of most of these chemicals?
- 60,000 - 80,000 chemicals;
- 1,000 added each year.
- 60K-70k there are significant questions about.
What type of chemicals receive the most testing and regulation?
Pesticides receive the most intensive testing before and after reaching the market
Describe the social and scientific significance of the following books: Silent Spring (Rachel Carson) & Our Stolen Future (Theo Colborn)
Silent Spring - Carson: People were being exposed to pesticides and other pollutants without their knowledge; The involuntary nature of some hazards, even if low risk, raises concerns. Decisions on the safety of chemicals were being entrusted to the wrong people; said that risk assessment procedures needed
Our Stolen Future - Colborn: Focused on Endocrine Disruption, especially through studies on the Great Lakes… It’s not cancer, but affects hormones that control development and physiology, a newly recognized category of risks.. 1996, legislation mandated testing for endocrine disruption. Tests on a first list of chemicals were not called for by EPA until Oct. 2009; a second revised list was issued June 2013 a long with a new type of risk assessment testing.
Describe the toxic triangle.
Similar to Triangle of Causation – Person, Agent, Environment
List and describe the three classes of problems presented by pesticides.
1) Insect Resistance: Huge increase in amounts of pesticeds applied since 1950s but percentage of crops lost has not dropped.
2) Global Proliferation: pesticides banned in developed countries are still being manufactured and shipped to LDCs
3) Health & Ecological Effects: Women and children work in the fields, pesticide containers used for water, many poisonings reported in LDCs
List the factors that govern toxicity.
Chemical properties, concentration (at target issues), length of time of exposure, route of exposure, interactions with other chemicals, other “individual” factors (age, exercise, stress, genetics)
Define Biomagnification and describe the two key chemical characteristics that are required in order for biomagnification to occur. How does methyl mercury fit those two characteristics?
An increase in whole body concentration with each step in the food web.
Requires:
- Persistence in environment and organisms
- Storage in tissues
Methyl mercury fits into these characteristics in that concentration of PCBs increases as you go up the food chain (ex. herrings and trout have the highest)
Compare and contrast the terms Bioconcentration, Bioaccumulation, and Biomagnification
Bioconcentration: uptake of contaminants from water only
Bioaccumulation: uptake of contaminants from all sources including water, food, and air
Biomagnification: increase in whole body concentrations of a contaminant at successively higher trophic levels
What are the major sites of absorption of contaminants?
Gastrointestinal tract, lungs, and skin
List the major types of mechanisms of toxicity..
- Blocking Active Site on the Substrate
- Inactivate or Remove Substrate
- Compete with Substrate for site on Enzyme
- Alter active site on Enzyme
Compare and contrast what activities release mercury into the environment and how then does the mercury reach humans in the Amazon and eastern North America??
Mercury reaches humans in North America due to fish consumption and how biomaginification applies to this ecosystem. Mercury affects those in the Amazon due to deforestation, which releases the mercury in the soil.
Both relate to Mercury entering the drinking water.
What is the precautionary principle and why is it an important concept?
The principle is used by policy makers to justify preventive measures in situations where there is the possibility of harm from taking a particular course or making a certain decision when extensive scientific knowledge on the matter is lacking. The principle implies that there is a social responsibility to protect the public from exposure to harm, especially when scientific investigation has found a plausible risk. These protections can be relaxed only if further scientific findings emerge that provide sound evidence that no harm will result.
Why is the precautionary principle a controversial concept?
Because applications of strong formulations of the PP can be used to block innovation, a technology which brings advantages may be banned by PP because of its potential for negative impacts, leaving the positive benefits unrealized.
The precautionary principle has been ethically questioned on the basis that its application could block progress in developing countries
Define: Endocrine Disruptors.
Exogeneous agents that interfere with the production, release, transport, metabolism, binding, action, or elimination of the natural hormones in the body responsible for the maintenance of homeostasis and the regulation of development processes
