Topic 22: Environmental

Hazards and Human Health, Part 1

CHEMICAL HAZARDS

• A hazardous chemical can harm humans or other animals because it may:– Be flammable– Be explosive– Be an irritant– Interferes with oxygen uptake

CHEMICAL HAZARDS• A toxic chemical can cause temporary or

permanent harm or death.• There are five categories:

– Neurotoxins– Mutagens– Carcinogens– Teratogens– Endocrine disrupters

More on endocrine disrupters

Figure 18-9Figure 18-9

Persistent organic pollutants (POPs)• PCBs• DDT• Atrazine• Dioxins

Hayes et al. 2002

Bioaccumulation & biomagnification

Chemicals in the environment: heavy metals(eg lead, arsenic, mercury, cadmium)

Chemicals in the home environment

• Phthalates• Bisphenol A (BPA)• Vinyl chloride

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

• Many factors contribute to harm from chemical hazards

• Children are more susceptible to chemicals, why?

LD-50/LC-50…ED-50/EC-50

Legislation• Federal Insecticide, Fungicide, and Rodenticide Act

– Gives EPA the authority to regulate all stages of pesticide production, distribution, and disposal.

– EPA can suspend the use of any pesticides found to pose unreasonable risks to humans or wildlife.

• Federal Food, Drug, and Cosmetic Act (1938, last amended in 2004)

– Lets EPA set tolerance levels for pesticide residues in food and livestock feed.

• Food Quality Protection Act (1996)– Amended the above two laws– Further requirements for assessing tolerance levels for pesticides in

food• Clean Air Acts

Hazardous waste

• Threatens human health or the environment in some way because it is – toxic– chemically active– corrosive– flammable– or some combination of the above

• The two largest classes of hazardous wastes are organic compounds (e.g. pesticides, PCBs, dioxins) and toxic heavy metals (e.g. lead, mercury, arsenic).

Conversion to Less Hazardous Substances

• Physical Methods• Chemical Methods• Incineration

Conversion to Less Hazardous Substances

• Biological Methods: – Bioremediation– Phytoremediation

Long-Term Storage of Hazardous Waste

• Hazardous waste can be disposed of on or underneath the earth’s surface.– Deep-well disposal– Surface impoundments

• Without proper design and care these can pollute the air and water.

Long-Term Storage of Hazardous Waste

• Long-Term Retrievable Storage

Hazardous Waste Regulations in the United States

• Two major federal laws regulate the management and disposal of hazardous waste in the U.S.:– Resource Conservation and Recovery

Act (RCRA)• Cradle-to-the-grave system to keep track of

hazardous material and waste.– Comprehensive Environmental

Response, Compensation, and Liability Act (CERCLA)• Commonly known as Superfund program.

Love Canal

• 21,000 tons of toxic waste was buried by Hooker Chemical Co. in the 1940s and 1950s in Love Canal, a neighborhood in Niagara Falls, NY.

• Love Canal sparked creation of the Superfund law, which forced polluters to pay for cleaning up abandoned toxic waste dumps.

• Video 1• Video 2

International agreements

• Basel Convention (1989)

• Persistent Organic Pollutants Treaty (2001)

Brownfields

• Abandoned industrial/commercial sites that are contaminated with hazardous waste– eg gas stations, factories, junkyards, old landfills

• Can be cleaned up and used for new purposes• EPA Brownfields Program gives low interest

loans to companies or groups that are willing to clean up an area and repurpose it.

RISKS AND HAZARDS

• Risk is a measure of the likelihood that you will suffer harm from a hazard.

• We can suffer from:– Biological hazards– Chemical hazards– Physical hazards– Cultural hazards