Chapter 20.1, pollution and human health
Environmental effects on health
Pollution kills directly (by poisoning us, lead, cancer)
Or indirectly (infectious diseases spread in polluted environments, cholera, river blindness)
World Health Organization (WHO) – ranks countries by poor health = # of days of healthy life lost to death and disease (per person each year)
Infectious diseases more prominent in developing countries with poor sanitation
Poor sanitation – bacteria in food gastrointestinal infections
Toxicology – study of the harmful effects of substances on organisms
How is it dangerous?
Ingested – taken in
How much of the pollutant is in the environment and how much gets into the body?
Dose – amount of a harmful substance that a person is exposed to.
Response – the damage that results from an exposure
Dependent on the size of the dose, how many doses, persons size, how well the body breaks down the chemical
Persistent chemical breaks down very slowly (like DDT) more people likely to come in contact with them in the environment and more likely to remain in the body
Dose response curve – shows the relative effect of various doses of drug or chemical on an organism as determined by experiments
Threshold dose – largest amount that has no adverse affect
Epidemiology – the study of the spread of diseases or how to prevent the spread of disease
Epidemiologists collect data from health workers on when and where cases of disease have occurred to find out it origin, how it spread and how future spread might be prevented
Risk is probability of a negative outcome (like disease, injury, death)
Risk assessment – an estimate of the harm posed by an action or substance
Compile and evaluate the existing information on the substance
Determine how people might be exposed
Determine the toxicity of the substance
Characterize the risk that the substance poses to the public
May lead to government regulation on how and where the substance can be used
(the EPA formulates these regulation in the US)
Pollution from natural sources – a problem when concentrated above natural levels
Radon – granite bedrock from cancer
Particulates – dust, soot, breath into lungs bronchitis, emphysema
From Dust storms, volcanoes, wild fires
Heavy metals – arsenic, cadmium, lead, mercury nerve damage
Pollution from human activities – chemicals, only 10% of commercial chemicals have been tested for their toxicity
About 1000 new chemicals are produced each year
Many linked to cancer, Parkinson’s and Alzheimer’s disease
Burning fuels – vehicles, furnaces, power plants and factories – gases and particulates asthma, heart disease, lung disorders
Pesticides – kill unwanted organisms such as insects, fungi, weeds – more food for us
Dangerous to humans if dose is large enough
Organophosphates – very toxic – cause nerve damage and cancer
Most poisoning occurs when people apply the chemicals
modern pesticides break down quickly into harmless substances
Persistent pesticides still used in developing countries, especially dangerous to children still developing internal organs and eat more in relation to body size
Chemicals that disrupt hormones (the endocrine system)
Hormones – chemicals that circulate in the bloodstream and control processes such as development of muscles and sex organs, control production of proteins
Hormone mimics – behave like natural hormones,
come from detergents and contraceptive pills
Hormone disruptors – prevent natural hormones (like testosterone) from functioning,
examples – phthalates used in cosmetics, hair dyes and fingernail polish
PCBs (polychlorinated bephenyls), lead, mercury, some pesticides
May be related to large increase in cancers of the prostate, testicles, ovaries, breasts in industrialized countries
50% Reduced sperm count in industrialized countries in last 50 years
Industrial chemicals – building, furnishing, manufacturing,
Lead, PCBs, -- do not break down, cause brain damage, learning disabilities, lower IQ
In fish from the great lakes
Waste disposal – inadequate waste disposal much of the pollution in the environment
Waster water Oil and toxic chemicals in water ways
Incineration toxic air pollution
Mining pollutes streams and rivers
Landfills leak
How to dispose of radioactive waste from nuclear power plants?
