| A | B |
|---|
| Toxicology | The study of the effects of poisonous substances on humans and other organisms |
| Toxicant | Any toxic agent |
| What makes a compound toxic | A substance's toxicity depends on it's chemical identity as well as its quantity; "The dose makes the poison" |
| Types of toxicants: Carcinogens | Cause cancer |
| Types of toxicants: Mutagens | Cause DNA mutations. Can lead to severe problems, including cancer |
| Types of toxicants: Teratogens | Cause harm to the unborn, can lead to birth defects |
| Types of toxicants: Allergens | Overactivate the immune system, causing an immune response when one isn't necessary |
| Types of toxicants: Nuerotoxins | Assault the nervous system |
| Bioaccumulation | Toxicants build up in animal tissues |
| Biomagnification | Toxicants pass up the food web and concentrate in top predators |
| How do compounds biomagnify | Top-predators gain the toxicants from their prey |
| Traits of compounds that biomagnify | Fat-soluble or oil-soluble; long-lived, mobile, and biologically active |
| DDT | Organic chlorinated organic insecticide. Widely used until banned in 1973. Impacted a wide range of species, target species (insects) adapted, non-target species (eagles) did not. DDT stays in the environment for a long time before it is broken down, and it bio-accumulated, devastating organisms high on the food chain. |
| Half life | The time it takes for a substance undergoing decay to decrease by half. DDT has a long half life, so it was in the environment a long time before it was broken down |
| Endocrine disruptors | Toxicants that interfere with the endocrine (hormone) system. Some affect an animal’s endocrine system by blocking the actions of hormones or accelerating their breakdown. Others mimic hormones. Dropping sperm counts: Some pesticides mimic estrogen and as a result suppress males’ reproductive systems, contributing to high sterility rates in men. |
| Heavy metals | High molecular weight metals. Some are essential to the biological processes, but all are toxic at high concentrations |
| Sources of heavy metals | Naturally occurring. Environmental loading increased by strip mines, fossil fuel combustion, coal ash piles, etc. |
| Mercury | Bio accumulates and doesn’t break down into less-toxic compounds. By-product of gold and silver mining, released into the air by industries burning fossil fuels, and by volcanoes. |
| Oil | 10% of the oil entering the environment is from natural oil seeps, the other 90% is from anthropogenic sources (humans). |
| Dioxins | Chlorinated organic compounds. They are hormone mimicking and contribute to falling fertility rates. Animals tend to bio accumulate dioxins, which are often in high concentrations in breast milk. They impact the reproductive, immune, development, and cause cancer. Dioxins travel through the air and end up in water. |
| PCB's | Polychlorinated Biphenyls are dioxins that are used in hydraulic fluid, transformers, capacitors and dielectric fuel. Causes skin problems, reproductive disorders, liver disease and other problems. Very long lasting in the environment and tend to bio accumulate. Manufactured in 1929 by Monsanto |
| TBT | TBT is extremely toxic. It us used in antifouling paints on boats so it accumulates heavily in the sediments of marinas. Considered by some scientist to be the most toxic compound to ever be used; harmful in the one part per billion concentration. Military Harbors are often heavily polluted with TBT. |
| PAHs | Polycyclic Aromatic Hydrocarbons. Comes from the combustion of organic matter. Component of cigarette smoke that causes cancer. Ex: petroleum burning, Creosote (a wood preservative), etc. |
