Toxic Chemicals

DDT ► An insecticide (kills insects)  Used during WWII to control malaria, typhus, body lice and plague. ► Still used in South America, Asia and Africa for this purpose.  Used on crops by farmers.  Used in homes. ► Widely used because it is effective, relatively inexpensive and lasts a LONG time in the environment.

Today ► EPA placed a ban on use in the US in 1972 due to damage it causes to ecosystems.  Persists in the environment  Accumulates in fatty tissue  Causes adverse health effects on wildlife. ► DDT breaks down into DDE causing thinning of eggshells in birds.  Resistance occurs in some insects (house fly) ► Can still be leagally manufactured but must be sold to foreign countries.

Toxicity ► DDT affects the nervous system by interferring with nerve impulses. by interferring with nerve impulses.  In humans exposure can cause a prickling sensation of them mouth, nausea, dizziness, confusion, headace, tremors, etc. ► Categorized as a carcinogen (in animals). ► Gets stored in fatty tissue.  When fat is metabolized during periods of starvation gets released into blood and affects liver and nervous system. ► Excreated through urine, feces, or breast milk (used to measure a or breast milk (used to measure a populations exposure). populations exposure).

How ling does it last? ► The soil half-life (the time required for half of the chemical to degrade) is from 2-15 years. ► The water half life of DDT is about 150 years.  Highly toxic to aquatic animals (heart and brain) (heart and brain)

PCB’s (Aroclor) ► Used a lot in industry due to their non-flamability.  Transformers and capacitors  Other electrical equipment including voltage regulators, switches, bushings, and electromagnets  Oil used in motors and hydraulic systems  Old electrical devices or appliances containing PCB capacitors  Fluorescent light ballasts  Cable insulation  Thermal insulation material including fiberglass, felt, foam, and cork  Adhesives and tapes  Oil-based paint  Caulking  Plastics  Carbonless copy paper  Floor finish

Today ► Ban placed on PCB’s in  There are still products from before the ban that can cause harm. ► Still released into the environment from  Poorly maintained hazerdous waste sites.  Disposal of materials into common landfills.  Burning materials containing PCB’s.  Leaks or releases from electral transformers.

Toxicity ► Can cause cancer. ► Compromises immune systems ► Reproductive effects  Low birth weights, conception rates, live birth rates and reduced sperm count. ► Nurological effects  Visual recognition, short term memory, learning ► These studies were conducted using PCB’s found in breast milk. ► Affects the thyroid gland in our endocrine systems (growth and development) THIS IS BAD STUFF!

How Long Does it Last? ► It takes many years for this substance to break down in the environment. ► It cycles between the land, air and water.  Found all over the world (even the poles!) ► Can accumulate in the leaves of plants and food crops. ► Taken into the bodies of aquatic organisms and can be passed to organisms and can be passed to us when we eat contaminated fish. us when we eat contaminated fish.

Mercury ► A naturally occuring metal.  Enters the air by ► Mining ore deposits ► Burning coal or waste ► Manufacturing plants  Enters the water or soil by ► Natural deposits ► Disposal of wastes ► Vocanic activity ► Can be form by bacteria (methylmercury) (methylmercury)  Builds up in the tissue of fish (larger fish = more mercury) (larger fish = more mercury)

Exposure ► Elemental mercury can be found in:  Glass thermometers  Electrical switches  Fluorescent light bulbs  Older dental fillings  Some medical equipment ► Inorganic mercury can found in:  Batteries  Chemistry labs  Some disinfectants ► Fumes from burning coal converted into organic mercury by certain organisms. ► Fish that have eaten a form of organic mercury called methylmercury methylmercury

Effects of Exposure ► ► Methylmercury and metallic mercury vapors are the most harmful, because more mercury in these forms reaches the brain.   Permanently damage the brain, kidneys, and developing fetus. ► ► Effects on brain functioning may result in irritability, shyness, tremors, changes in vision or hearing, and memory problems. ► ► Short-term exposure to high levels of metallic mercury vapors may cause effects including lung damage, nausea, vomiting, diarrhea, increases in blood pressure or heart rate, skin rashes, and eye irritation.