Environmental Science: Toward a Sustainable Future Richard T. Wright Environmental Hazards and Human Health Chapter 15

What Do You Perceive as Risky? List your daily activities, (e.g. consuming nonorganic food, driving a car, using a computer, smoking, washing hands after using the toilet, etc.). Using death as an outcome, rank or activity levels in order of risk. For example, smoking is more hazardous than consuming nonorganic food, and not washing your hands after using the toilet is riskier than consuming nonorganic food. For the most risky behaviors, determine why you might perceive your risky behavior as not very risky.

Risk – It comes with the territory The deer tick (Ixodes scapularis) is a vector for Lyme disease.  Victim develops a rash, fever chills, fatigue, and headaches. If treatment is delayed, symptoms can become chronic and lead to long-term arthritis, memory impairment, numbness, and pain. Relationship between oak trees, gypsy moths, and Lyme disease  Gypsy moth is an introduced pest capable of ravaging forests

Risk – It comes with the territory White-footed mice feed on gypsy moths, thus regulating damage to the forest – the forest thrives Oak forest produces bumper crop of acorns More acorns for mice to feed on Increases rate of Lyme disease incidences

Risk – It comes with the territory

The Old Enemies Common, familiar disease take the greatest toll on human health.  Malaria  Diarrhea  Respiratory viruses  Worm infestations  Cancer (exposure to chemicals in environment) These are kept at bay in developed countries, but still wreak havoc in developing countries.

The Old Enemies Environmental health – study of the connections between hazards in the environment; also human disease and health Issue in this chapter is human health, not that of the environment

Environmental Hazards and Human Health Links between human health and the environment Pathways of risk  Pathways whereby humans encounter hazards Risk assessment  Interventions that can alleviate the risks to health

15.1 Links Between Human Health and the Environment Environment: combination of physical, chemical, and biological factors Hazard: anything that can cause injury, death, disease, damage to personal/public property, or deterioration or destruction of environmental components Risk: probability of suffering a loss as a result of exposure to a hazard

15.1 Links Between Human Health and the Environment Health – “a state of complete mental, physical and social well-being, and not merely the absence of disease or infirmity” ~ WHO Health has many dimensions and to measure all for a society is impossible. To study environmental health we will focus on disease and consider health to be the “absence of disease”.

15.1 Links Between Human Health and the Environment: The Picture of Health Morbidity: incidence of disease in a population Mortality: incidence of death in a population Epidemiology: study of presence, distribution, and control of disease in a population Measures used to study Disease in societies. Records of death kept and so possible to analyze causes.

Causes of Human Mortality

15.1 Links Between Human Health and the Environment: The Picture of Health Cultural Biological Physical Chemical What is it in the environment that brings the risk of injury, disease, or death to people? To answer this question, we must understand the four classes of Hazards: cultural, biological, physical, and chemical.

15.1 Links Between Human Health and the Environment: Cultural Hazards Many of the hazards that contribute to mortality and disability are a matter of choice or are at least influenced by choice. People engage in risky behavior and subject themselves to hazards.  We eat too much, drive too fast, use drugs, consume alcoholic beverages, smoke, sunbathe, hang glide, risky sexual practices, get too little exercise, and choose hazardous occupations.  Factors such as living in inner cities, engaging in criminal activities are also sources of cultural hazards.

Deaths from Various Cultural Hazards Most deaths are the result of cultural hazards, but they are also the most preventable.

15.1 Links Between Human Health and the Environment: Biological Hazards These are inevitable components of our environment and are there regardless of human presence.  Some leading causes are pneumonia, diphtheria, tuberculosis, whooping cough, influenza, and streptococcal infections. Not limited to but include pathogenic bacteria, fungi, viruses, protozoans, and worms.

Global Map of Tuberculosis, 2001 While no longer the number one killer, tuberculosis is still a major player. Our complacency with treatment methods in the last few years has led to a resurgence, which can be traced to AIDS and HIV; resulting in compromised immune systems. There are also several drug resistant strains of this microbe.

15.1 Links Between Human Health and the Environment: Biological Hazards More prevalent in, but not exclusive to, developing countries. Contamination of food and water.  Lack of resources for sanitation.  Lack of education. Ideal climates for transmission of vector-borne diseases like malaria.  The lack of such resources is considered a hazard.

Malarial Parasite Life Cycle The parasite harms the human host by destroying red blood cells and releasing fever-inducing substances into the bloodstream.

15.1 Links Between Human Health and the Environment: Physical Hazards Natural disasters, e.g., tornadoes, floods, hurricanes, and wildfires. Avoidance of risk important in prevention, e.g., building homes in floodplains, and living on the coast Climate change: consequences of elevated greenhouse gases Most devastating consequences occur to those least capable of anticipating and dealing with the effects.

15.1 Links Between Human Health and the Environment: Chemical Hazards Industrialization has brought with it a host of technologies that employ chemicals Exposure through ingestion, inhalation, absorption through skin.  May be direct use or accidental Many chemicals are toxic at low levels, though different people have different thresholds for substances.  Children are at greater risk than adults.

15.1 Links Between Human Health and the Environment: Chemical Hazards Many chemicals are hazardous to human health even at low levels. 74 chemicals are known to be carcinogenic.  Cancer takes a very large toll in the developed countries, accounting for one-third of mortality. Environmental carcinogens initiate mutations in DNA; several mutations lead to a malignancy

15.2 Pathways of Risk: The Risks of Being Poor One major pathway for hazards is poverty No money for health insurance Higher probability of exposure to environmental hazards Those who are dying from infectious diseases are those who lack access to adequate health care, clean water, nutritious food, healthy air, sanitation, and shelter. The number one hazard for children is that they are underweight.

The 10 Leading Global Risk Factors These 10 factors are responsible for more than one-third of all deaths and much of the global burden of disease.

15.2 Pathways of Risk: The Risks of Being Poor Factors contributing to the environmental health of a nation include:  Education  Nutrition  Commitment from government  More equitable distribution of wealth

15.2 Pathways of Risk: The Cultural Risk of Tobacco Use Approximately 442,300 deaths in the U.S. are attributed to smoking.

15.2 Pathways of Risk: The Cultural Risk of Tobacco Use In the U.S., several measures have been taken to regulate this cultural hazard.  Products are highly taxed One of the most effective ways to reduce smoking, especially in young people. Since the warnings began, the smoking population in the U.S. has gradually decreased.

15.2 Pathways of Risk: Risk and Infectious Diseases Epidemiology is described as “medical ecology”, which traces disease as it occurs in geographic locations, as well as tracing the mode of transmission and consequences of disease. One major pathway of risk is contamination of food and water.  Inadequate hygiene  Inferior sewage treatment

15.2 Pathways of Risk: Risk and Infectious Diseases Genome sequencing of the Anopheles mosquito. Change in land use practices: wetland development. New effective anti- malarial drugs. Bed nets and drugs have decreased incidences of death by malaria by 98% in seven years.

Worldwide Distribution of Malaria Malaria is found in the tropics and subtropics around the world. Drug resistance and environmental disruptions are contributing to the strong resurgence of the disease in the last two decades.

15.2 Pathways of Risk: Toxic Risk Pathways How is it that people are exposed to chemical substances that can bring them harm? Categories of impact of airborne pollutants  Chronic: effect takes place over a period of years.  Acute: life-threatening reaction within a period of hours or days.  Carcinogenic: pollutants initiate cellular change leading to cancer.

15.2 Pathways of Risk: Toxic Risk Pathways Hazardous fumes from home products Well-insulated buildings Long exposure to indoor air 90% of our time is spent indoors! Those who spend the most time indoors are the most susceptible: small children, pregnant women, the elderly and chronically ill.

15.2 Pathways of Risk: Toxic Risk Pathways At least 3 billion people still rely on bio- fuels like wood and animal dung for cooking and heating. Often, fireplaces and stoves are improperly ventilated.  Acute respiratory infections in children  Chronic lung diseases  Lung cancer  Birth-related problems

15.3 Risk Assessment The process of evaluating the risks associated with a particular hazard before taking some action in which the particular hazard is present.  Ex: the risk of dying in a ca accident is 1.6 per 10,000 – those who never set foot in a motor vehicle will live on average 300 days longer. Not very many people actually make choices in their lives based on these risk assessments.

Loss of Life Expectancy from Various Risks One way to illustrate the relative risks posed by different hazards is to rank them in terms of average days of lost life associated with each risk.

15.3 Risk Assessment: Environmental Risk Assessment by the EPA Hazard assessment (What chemicals cause cancer?)  Examines evidence linking a potential hazard to its harmful effects.  When the linkage is not obvious, we can gather data from epidemiological science.  Best method for risk assessment has resulted in scores of chemicals being added to the list of carcinogens.

15.3 Risk Assessment: Environmental Risk Assessment by the EPA Dose-response assessment (How much?)  When tests (animal or human) show a link between chemical and ill effects, the next step is to analyze the relationship between the dose and severity of response. Followed by Exposure Assessment  Identify human groups already exposed to the chemical and calculate dosages for the length of time of their exposure.

15.3 Risk Assessment: Environmental Risk Assessment by the EPA Exposure assessment (How long?)  Its not prudent to wait 20 years to find out if food additives cause cancer, so we turn to animal testing to find out what might happen.  Usually takes about three years. Objections arise from physiological differences between humans and rodents, dose amounts, and ethical grounds to the use of animals for such purposes.

15.3 Risk Assessment: Environmental Risk Assessment by the EPA Risk characterization (How many will die?)  Pull together all information gathered in the first three steps in order to determine the risks and its underlying uncertainties.

15.3 Risk Assessment: Public-Health Risk Assessment 1. Potential global impact 2. High likelihood of causality 3. Modifiability 4. Availability of data For example, we will look at obesity…

15.3 Risk Assessment: Public-Health Risk Assessment 1. Potential global impact Likely to be among the leading causes of poor health and mortality. 2. High likelihood of causality Possible to trace the cause-effect relationship between poor health and the factor in question. Overweight people are more likely to develop diabetes, high blood pressure, etc.

15.3 Risk Assessment: Public-Health Risk Assessment 3. Modifiability It is possible to develop countrywide risk reduction policies that would lessen impact. 4. Availability of data There must be reliable data on the prevalence of the risk factor and its relationship to disease and mortality.

15.3 Risk Assessment: Risk Management Usually involves:  Cost–benefit analysis Involves a thorough review of the available information pertaining to the hazard in question and the risk characterization of that hazard.  Risk–benefit analysis Decision as to whether the weight of the evidence justifies a regulatory action.  Public preferences Public opinion can play a powerful role in both processes

15.3 Risk Assessment: Risk Perception Hazard: expresses primarily a concern for fatalities only.  The reason for inconsistency between public perception and actual risk is that the public perception of risks is often more of a matter of outrage than hazard.

15.3 Risk Assessment: Risk Perception Outrage includes:  Lack of familiarity with technology  Extent to which the risk is voluntary  Public impressions of hazards  Overselling safety  Morality  Control  Fairness Hazard = expresses primarily a concern for fatalities only. Outrage = expresses a number of additional concerns.

15.3 Risk Assessment: Risk Perception Some suggest we use distributive justice in making decisions about risk  Ethical process of making certain that everyone receives proper consideration  Should reduce environmental racism/injustice

15.3 Risk Assessment: Risk Perception Not a perfect system Precautionary principle  Lack of certainty should not be used as a reason for preventing environmental degradation/hazards.

Thinking Environmentally Imagine that you have been appointed to a risk-benefit analysis board. Explain why you approve or disapprove of the widespread use of:  Genetically modified foods  Drugs to slow the aging process  Nuclear power plants  Asbestos Each of these responses will be a personal opinion based upon risk perception. The personal opinion should be justified by data. It will be possible to approve or disapprove of the widespread use of any of these items based upon how the benefits and risks are balanced.

End of Chapter 15