Human Health and Environmental Risk Chapter 17

Awareness Awareness © Sylvia Stults Broken bottles and charred pieces of glass Wadded up newspapers tossed on the grass Pouring of concrete and tearing out trees This is the environment that surrounds me? Poisons and insecticides sprayed on our food Oceans filling with thick oil crude All sea life destined to a slow awful doom These are the things we are to consume? Mills pumping out iron expelling yellow fumes Airlines emitting caustic gases from fuels Weapons of destruction tested at desolate sites And this is the air that's to sustain life? There has to be something that someone can do Like raise the awareness to those around you That if we don't heed the problem at hand It's your life that's at stake, the destruction of man.

Three categories of human health risks Physical: accidents or environmental factors Biological: those associated with diseases Chemical: associated with exposure to chemicals naturally occurring and man made

Biological Risks Infectious diseases- those caused by infectious agents, known as pathogens. Examples: pneumonia and venereal diseases Chronic disease- slowly impairs the functioning of a person’s body. Acute diseases- rapidly impair the functioning of a person’s body. Endemic- rapid increase Pandemic- when and epidemic occurs over a large geographic region

Factors that contribute to disease.

Historical Diseases Plague-one of the most familiar in human history. Plague is caused by and infection from a bacterium that is carried by fleas. It is estimated to have killed hundreds to millions of people worldwide. Malaria- is caused by an infection from any one of several of species of protists in the genus Plasmodium. They are transmitted by mosquitos. Tuberculosis-highly contagious disease caused by bacterium that affects primarily the lungs.

Pathogens can travel in a variety of ways to infect humans.

Emergent Diseases Emergent diseases are diseases that were not common or described for at least the prior twenty years. HIV/AIDS Ebola Mad Cow Disease Bird Flu West Nile Virus What could be added to this list?

Chemical Risks Neurotoxins- chemicals that disrupt the nervous system Carcinogens- chemicals that cause cancer Teratogens- chemicals that interfere with the normal development of embryos or fetuses Allergens- chemicals that cause allergic reactions Endocrine disruptors- chemicals that interfere with the normal functioning of hormones in an animal’s body “All substances are poisons: there is none which is not a poison.  The right dose differentiates a poison and a remedy." Paracelsus (1493-1541)

A 2002 USGS study found that 80% of U S streams contain 82 wastewater contaminates including antibiotics, perfume, detergents, steroids, disinfectants, and on…..

Laws Toxic substances are regulated by the EPA. The toxic substance Control Act of 1976 gives the EPA the authority to regulate many chemicals though excluding food, cosmetics, and pesticides. Pesticides are under the Federal Insecticide, Fungicide, and Rodentide Act of 1996. Under this law a manufacturer must demonstrate that a pesticide will not generally cause unreasonable adverse effects on the environment.

Concentrations of Chemicals To understand the risk posed by chemicals scientists have to determine the concentrations that cause harm. They do this by using dose-response studies, prospective studies, and retrospective studies. Because of the short duration they are called acute studies. Dose-Response Studies- expose animals or plants to different amounts of chemicals and then observe a variety of possible responses. LD50- lethal dose that kills 50% of the individuals ED50- effective dose that causes 50% of the animals to display the harmful but nonlethal effect

Synergistic interactions- when two risks come together and cause more harm that one would. For example, the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.

Bioaccumulation Biomagnification bioaccumulation- an increased concentration of a chemical within an organism over time Biomagnification- the increase in a chemical concentration in animal tissues as the chemical moves up the food chain.

Persistence Persistence- how long a chemical remains in the environment

Rachel Carson Perhaps the finest nature writer of the Twentieth Century, Rachel Carson (1907-1964) is remembered more today as the woman who challenged the notion that humans could obtain mastery over nature by chemicals, bombs and space travel than for her studies of ocean life. Her sensational book Silent Spring (1962) warned of the dangers to all natural systems from the misuse of chemical pesticides such as DDT, and questioned the scope and direction of modern science, initiated the contemporary environmental movement. DDT was banned in 1973.

Risk Analysis What do you think are the top killers of people?

Risk Assessment Qualitative Risk Assessment Making a judgment of the relative risks of various decisions Probability- the statistical likelihood of an event occurring and the probability of that event causing harm Quantitative Risk Assessment The approach to conducting a quantitative risk assessment is: Risk= probability of being exposed to a hazard X probability of being harmed if exposed

Worldwide Standard of Risk

Stockholm Convention In 2001, a group of 127 nations gathered in Stockholm, Sweden, to reach an agreement on restricting the global use of some chemicals 12 chemicals were to be banned, phased out, or reduced These include DDT, PCBs, and certain chemicals that are by-products of manufacturing processes.

Asbestos