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?