Chapter 15 APESEnvironmental Risks

& Human Health

“Environmental Health” - really Human Health Studies

• WHO = World Health Organization defines health as “state of complete mental, physical and social well being” but in order to study environmental health we will focus on health simply as the absence of disease. Helps to facilitate MDG’s to decrease poverty and decrease world wide mortality rates.

• CDC of the US = Centers for Disease Control and Prevention has a mission to promote health and quality of life by preventing and controlling disease, injury and disability.

• EPA of the US = Environmental Protection Agency provides risk assessments of the scientific characterizations of the hazards, dose-responses and exposure outcomes, summarize the risk and its uncertainties (also environmental ministries of other countries).

• Lawmakers and administrators are responsible for risk management determining a plan (cost-benefit, risk-benefit, public preferences leading to possibly taxation penalties or regulations.

• Hyogo Framework for Action in Kobe Japan 2005 – disaster risk reduction blueprint (prioritize with dollars, educate, reduce risk and be prepared to act)

Who is involved in monitoring environmental health conditions?

Hazard vs. Risk• A hazard is anything that causes:

1. Injury, disease, or death to humans2. Damage to property3. Destruction of the environment

4 Types of Hazards:• Cultural - a risk that a person chooses to engage in (like use of

alcohol or tobacco)• Biological – caused by pathogenic bacteria, fungus, viruses,

protozoans and worms (pneumonia, influenza)• Physical – natural disasters (floods, earthquakes)• Chemical – synthetic man-made chemicals, many used in

industrial processes (pesticides, fuels, meds)

Risk• Risk

The probability of suffering (1, 2, or 3) as a result of a hazard Usually expressed in terms related to fatalities, such as lost life

expectancy or DALY’s DALY (disability-adjusted life year) is equal to the loss of one

healthy year of life caused by a hazard

• Risk Perception What people think the risks are, intuitive judgments about risks

Public Risk Perception is exacerbated by outrage with:•Unfamiliar technology (scary? like medicines)•Involuntary exposure as opposed to voluntary or something you are in control of (driving vs. flying)•Heavy media coverage or lots of death at one time (although 430,000 deaths a year due to tobacco use, still allowed to sell cigarettes)•Lack of morality or fairness (poorest or youngest are effected, why should I accept any risk if the benefits all go to someone else?)•Overselling of safety, excessive advertising

3 Toxic Chemical Pathways

Ways that people are exposed to chemical substances and how they bring about harm

• Chronic = pollutants cause the gradual deterioration of physiological functions over a period of years (tough to link causality with planned studies, often done by epidemiological studies after the fact)

• Acute illness = pollutants bring on life-threatening reactions within a period of hours or days

• Carcinogenic = cancer-causing, pollutants initiate changes within cells that lead to uncontrolled growth and division (tumors), which is frequently fatal (also called mutagenic)

These terms are essential• Epidemiology = study of the presence, distribution and

prevention of disease in populations (study of the ecology of pathogens)

• Toxicology = studies the relationship of toxic substances in environment and health problems

• Morbidity = incidence of disease in a population

• Mortality = incidence of death in a population• DALY (disability-adjusted life year) = equal to the loss of one healthy

year of life caused by a hazard, often used to compare various risk factors

• Risk = hazard x vulnerability (related to both terms)

See Fig 15-9 10 leading global risk factors, Fig 15-16 Loss of life expectancy or Table 15-3 Probability of dying

10 leading global risk factors

• WHO lists “underweight” (or malnourishment) as # 1 risk factor for premature death, heavily linked to poverty

• This is followed by unsafe sex, blood pressure, tobacco, alcohol, unsafe water, cholesterol, indoor air pollution, iron deficiency and obesity.

Cigarette Smoking

• Leading cause of cancer in U.S.

• Can cause cancer, lung disease, a bigger risk of death in addition with other types of air pollution.

• Highest health risk in U.S.

Cost-Benefit AnalysisRisk Analysis

• Public policy is generated more by the perceived risks of the public than through logic of cost-benefit analysis.

• A cost-benefit analysis is a requirement for every regulatory action for EPA

• Also is a means of deciding whether or not to proceed with a given project.

• Common indoor air pollutants like: cigarette smoking, asbestos, radon, and formaldehyde require risk analysis

Lethal dose at 50% = LD50

• The LD50 is a standardized measure for comparing the toxicity of chemicals.

• The LD50 is the dose that kills half (50%) of the animals tested in an experiment.

• LD50 tests result in the deaths of many laboratory animals and the data are often controversial.

• Oral LD50 in rats for DDT is 87 mg/kg. So what does that mean for humans?

• Threshold level of toxicity = The dose below which no lethal effects are observed and/or above which the lethal effects are apparent.

Determine toxicity for a chemical by using a Dose-Response Curve

If the response is expected to be death, what kind of organism should be tested?

Cancer• Proving that a chemical is a cause of cancer

is hard because a long time may elapse between exposure and development of the cancer

• If cancer risk from exposure to a chemical is less than 1/1,000,000 then no EPA regulation is needed.