Environmental Hazards and Human Health

Environmental Hazards and Human Health
CHAPTER 17 Environmental Hazards and Human Health

An introduction to hazards and human health
The highly virulent H5N1 avian flu first appeared in 1997 Infecting poultry, other birds, and humans Hundreds of millions of poultry have been slaughtered The 2009 H1N1 swine flu outbreak spread rapidly The World Health Organization declared a global influenza pandemic 39 new diseases have spread from animals to humans SARS, the Ebola virus, West Nile virus, hantavirus New diseases will appear as we change the environment

Countries with avian flu, 2008

The old enemies The new, emerging diseases are not our greatest threat
The common, familiar ones take the greatest toll Malaria, diarrhea, respiratory viruses, worms Especially in developing countries In developed countries, cancer is the killer most closely linked to the environment Due to our exposure to chemicals Environmental health: connections between environmental hazards and human disease and death

Links between the environment and health
Pollution: the presence of a substance in the environment that because of its composition or quantity prevents functioning of natural processes and produces undesirable environmental or health effects Pollutant: any material that causes pollution Usually by-products of some desirable action Agriculture, comfortable homes, transportation, etc. Pollution has increased due to population and consumption Along with accumulation of nonbiodegradable products (e.g., plastic, synthetic organic chemicals)

Categories of pollution

Pollution is everywhere
Any part of the environment can be polluted Almost anything can be a pollutant The only criterion? The addition of a pollutant results in undesirable changes Impacts can be: Aesthetic: hazy air, litter On ecosystems: fish or forest die-offs On human health: water contaminated with waste Local (a contaminated well) or global (ozone depletion) Too much of a natural compound (e.g., fertilizer)

Our existence necessitates waste production
We must meet our present needs by managing wastes So they don’t jeopardize present or future generations Identify the material(s) causing the pollution Identify the source(s) of the pollutants Clean up the environment Prevent pollutants from entering the environment Avoid the pollution altogether Transitioning to a sustainable society will require a technology transition from pollution-intensive to environmentally friendly processes

Environmental health Environment: the whole context of human life
The physical, chemical, and biological setting of where and how people live Home, air, water, food, workplace, climate, etc. Hazard: anything that can cause: Injury, disease, death to humans Damage to personal or public property Deterioration or destruction of environmental parts

Hazards, risk, and vulnerability
Undesirable consequences do not necessarily follow a hazard Risk: the probability of suffering injury, disease, death, or some loss as a result of exposure to a hazard Vulnerability: some people (e.g., the poor) are more vulnerable to certain risks Risk = Hazard x Vulnerability The presence of avian flu in poultry: a hazard that presents the risk of humans getting the disease People working with poultry are more vulnerable

The picture of health Health: a state of complete physical, social, and mental well-being Not just the absence of disease or infirmity Environmental health focuses on disease Health: the absence of disease Two measures are used to study disease Morbidity: the incidence of disease in a population Mortality: the incidence of death in a population Epidemiology: the study of the presence, distribution, and prevention of disease in populations

Public health One of the most important activities of government: protecting the health of its people Centers for Disease Control and Prevention (CDC) Part of the Department of Health and Human Services Provides tools and information to protect health Involved in health risk management and prevention Each state has its own public-health agency Can require shots, quarantines, monitoring diseases, etc. The U.S. has a huge health care industry Medicare, Medicaid, hospitals, physicians, etc.

Other countries Most countries have a ministry of health that acts on behalf of its people to manage and minimize health risks Health policies are limited by information and funding Limited funds should go to strategies that achieve the greatest risk prevention Countries have access to the WHO Established by the UN in 1948 Everyone should get the highest possible level of health Staffed by professionals and governed by the World Health Assembly

Life expectancy A universal indicator of health
In 1955, it was 48 years It is now 68 years and will rise to 73 by 2025 Longer lives: due to social, medical, economic advances Epidemiologic transition: decreasing death rates accompany development Infectious diseases are replaced by diseases of aging But 92 million children still die each year Common diseases kill 47% of people in poor countries Industry and intensive agriculture have their own hazards

Environmental hazards
Four classes of environmental hazards: Cultural, biological, physical, chemical There are two ways to consider hazards to health Lack of access to resources (clean water, food) Exposure to hazards in the environment that brings risk of injury, disease, or death Cultural hazards: many factors that cause death or disability are a matter of choice People engage in risky behavior (smoking, drinking, drugs, don’t exercise, risky sexual practices, etc.)

Cultural hazards can kill people
People derive pleasure or other benefits from cultural hazards They are willing to take the risk they will not be hurt Other cultural sources of mortality: living in inner cities, criminal activity Cultural hazards cause 40% of U.S. deaths Many causes of death are preventable Acquired immune deficiency syndrome (AIDS) is a sexually transmitted disease It is caused mainly by high-risk sexual behavior

Deaths from cultural hazards in the U.S.

Biological hazards Through history, humans have battled bacteria and viruses The black plague and typhus The 19th century brought vaccinations and bacteriology Bacteriologists discovered most bacterial diseases The 20th century brought virology, antibiotics, immunizations Global eradication of smallpox; victory over polio The battle will never be won Diseases are inevitable

Respiratory diseases 25% of deaths are due to infectious or parasitic diseases Respiratory infections (diphtheria, influenza, etc.) are the leading causes of death in this category Pneumonia is the most deadly of these diseases Respiratory diseases lead to death in developing nations Mostly in children already weakened Most children are infected by rotavirus They die from untreated diarrhea in developing nations Food or water contaminated with bacteria also cause diarrhea

Jim Henson

Tuberculosis, malaria, and parasites
Mycobacterium tuberculosis infects one-third of all people Tuberculosis has resurged due to complacency, HIV-weakened immune systems, and drug-resistant strains Malaria kills 881,000 people each year A mosquito infects a person with a protozoan parasite Red blood cells are destroyed, leading to anemia, fever, chills, and malaise 3.5 billion people suffer from parasitic worms Hookworms and schistosomes

Global map of tuberculosis

Life cycle of malarial parasite

Physical hazards Natural disasters include hurricanes, tornadoes, floods, fires, earthquakes, landslides, and volcanic eruptions The result of hydrological, meteorological, or geological forces Unimaginably dreadful events occurred in The Indian Ocean tsunami, Hurricane Katrina, Pakistan’s earthquake Some hazards can’t be anticipated (tornadoes, earthquakes) Others occur because of where people decide to live

Dangerous physical hazards

Out of nowhere The U.S. has 780 tornadoes/year, more than any other place They are spawned from severe weather Winds can reach 300 mph They can kill hundreds Some natural disasters are unavoidable Earthquake-resistant buildings can be constructed Tsunami early warnings are increasing The poor are the least capable of anticipating and dealing with disasters

In harm’s way Much loss from natural disasters is due to poor environmental stewardship Deforested hillsides Building on floodplains, below volcanoes, on geologic faults, marshes, and mangrove forests People assume disasters happen to other people They take risks to live in desirable places Stupid zones could be created for areas that shouldn’t be built Areas prone to hurricanes, earthquakes, volcanoes, etc.

Chemical hazards Industrialization has resulted in technologies that use chemicals Cleaning agents, pesticides, fuels, medicines, paints, etc. Exposure is through ingestion, breathing, the skin, direct use, or by accident Toxicity: condition of being harmful, deadly, or poisonous Depends on exposure and dose (the amount absorbed) Different people have different thresholds of toxicity Children and embryos are most sensitive

Industrial processes and hazards

Carcinogens Many chemicals are hazardous even at very low levels
Heavy metals, organic solvents, pesticides Acute poisoning episodes are understandable and preventable But it is hard to determine effects of long-term exposure to low levels of substances Carcinogens: cancer-causing agents Cancer develops over decades, so it is hard to connect cause with the effect There are 51 known and 188 suspected carcinogens Developing nations have rising exposure to chemicals

Carcinogenesis Carcinogenesis: the development of a cancer
It is a process with many steps spread over a long time Five or more mutations must occur to initiate a cancer Environmental carcinogens bind to, or disrupt, DNA This prevents DNA from functioning With a mutation, it may take 40 years to lead to a malignancy Cells grow out of control and form tumors Which may metastasize (spread) The best strategy is prevention

Pathways of risk What pathways lead from risks (of infection), exposure (to chemicals), and vulnerability (to hazards) to human deaths? A very small number of risk factors cause the vast majority of premature deaths and disease One major pathway for hazards: poverty The world’s biggest killer in both developing and developed nations People lack access to health care, clean water, nutritious food, healthy air, sanitation, and shelter

The 10 leading global risk factors

Poor vs. rich nations Underweight children: the world’s number one risk factor Strongly related to poverty Malnutrition kills over 2.2 million children/year Wealthy nations have healthier populations People protect themselves from hazards They die from diseases of old age (cancer, heart disease, etc.) People in developing nations die from infectious diseases Developed nations have better-educated people They improve their hygiene, immunize children, recognize dangerous symptoms (e.g., dehydration)

Public-health clinics

Priorities Education, nutrition, and wealth do not explain everything
A nation may make deliberate policy choices to improve the health of its population Instead of militarization or power sources Costa Rica, China, and Sri Lanka have longer life expectancies and lower infant mortality than expected They focused public resources on immunization, upgrading sewer and water systems, and land reform

The cultural risk of tobacco use
Lifestyle choices pose a high risk of accidents and death Not exercising, overeating, fast driving, alcohol, etc. Tobacco is the leading cause of death in the U.S. Fourth cause of death globally Tobacco use is declining in developed countries But not in developing countries It remains high in former socialist countries of eastern Europe 19.8% (43.4 million) of U.S. adults smoke Half will die or become disabled

U.S. deaths caused by smoking

Marlboro country? Tobacco is the only product sold that kills half its users It is clearly correlated with cancer and other lung diseases It is responsible for 29% of U.S. cancer deaths 5.4 million die worldwide each year Synergistic effects: smokers living in polluted air or working with asbestos have higher rates of lung cancer Black lung disease occurs mainly in smokers Smoking costs the U.S. $193 billion/yr in health care costs and lost job productivity

Decreasing tobacco use
Raising taxes: the most effective measure to reduce tobacco use Providing billions of dollars to state and federal governments Other measures to reduce smoking include warnings, smoke-free workplaces, non-smoking areas, and banning smoking on domestic flights The U.S. smoking population dropped from 42% to 19.8% since warnings began

Secondhand smoke In 1999 the EPA classified environmental tobacco smoke (ETS), secondhand smoke, as a Class A (known) carcinogen A serious and substantial public health risk Specific steps now protect children in public places The Occupational Safety and Health Administration is working to protect workers from ETS In 1999, Congress gave the Food and Drug Administration sweeping power to regulate tobacco Overcoming efforts of the powerful tobacco lobby

Legally speaking The attorneys general of several states sued tobacco companies In 1998, 46 states reached a $246 billion settlement Tobacco companies would reimburse states for smoking-related illnesses Help finance programs to discourage smoking Other lawsuits have not been successful Judges ruled that earlier court rulings forbade them from imposing fines

FCTC and EMPOWER The WHO’s 2003 Framework Convention on Tobacco Control aims to reduce the spread of smoking Bill Gates and New York City’s Mayor Bloomberg gave the WHO $500 million to combat global smoking Monitor tobacco use and prevention policies Protect people from tobacco use Offer help to those who want to quit Warn about dangers of tobacco Enforce bans on advertising, promotion, sponsorship Raise taxes on tobacco

Bill Gates and Michael Bloomberg

Risk and infectious diseases
Epidemiology is “medical ecology” Epidemiologists trace a disease’s location, transmission, and consequences Infectious diseases and parasites are more common in developing countries Inadequate hygiene, inferior sewage treatment A lack of resources for public-health infrastructure Developed nations also have outbreaks of diseases In 1993 Milwaukee’s (Wisconsin) water supply was contaminated by animal wastes, hospitalizing over 4,000

Tropical diseases The tropics have ideal climates for insect-borne diseases Mosquitoes are vectors for yellow fever, dengue fever, elephantiasis, Japanese encephalitis, West Nile, malaria Malaria is the most serious Control of malaria focuses on vector control: using pesticides on the Anopheles mosquito Or treatment strategies: curing infected people Malaria has been eradicated in the U.S. DDT is a successful, yet controversial, control for mosquitoes in developing countries

Malaria incidence per 1,000 population, 2006

Net results Giving children insecticide-treated nets over their beds reduces mortality from all causes Bed nets, indoor DDT spraying, and effective drugs reduce malaria deaths A cost-effective, large-scale intervention in Africa The Plasmodium protozoan is becoming resistant to drugs Chloroquine is now ineffective against malaria ACT (artemisinin combination therapy) is effective But resistance is appearing

Insecticide-treated bed net

Good news Molecular biologists have sequenced the genomes of the Anopheles mosquito and P. falciparum parasite Targeting weak points in both organisms Development of new drugs and vaccines will further reduce malaria The Global Malaria Action Plan (GMAP): intends to eventually eradicate malaria Will require billions of dollars Will meet the Millennium Development Goal target

Toxic risk pathways Airborne pollutants are hard-to-control hazards
Hard to measure and avoid Three categories of impacts Chronic: pollutants cause gradual deterioration of physiological functioning over years Acute: pollutants cause life-threatening reactions within hours or days Carcinogenic: pollutants cause cellular changes leading to uncontrolled growth and division (cancer)

Indoor air pollution Indoor air pollution can pose an even greater health risk than outdoor air pollution Inside air can contain much higher levels of pollutants Indoor air pollution in developed countries is problematic More numbers and types of pollutants are being used Insulated buildings trap pollutants inside People spend more time indoors than out (e.g., children, pregnant women, the elderly or sick) There are many sources of indoor air pollution The least excusable is from smoking

Indoor air pollution

Developing countries Developing nations have the most serious threat
Three billion use wood or dung for cooking and heating Fireplaces, stoves, etc. are not properly ventilated Exposing people to carbon monoxide, nitrogen and sulfur oxides, soot, benzene (a carcinogen) Problems associated with indoor cooking: acute respiratory infections, chronic lung disease (asthma, bronchitis), lung cancer, birth defects Solutions? Ventilated, efficient stoves Using bottled gas or liquid fuels instead of biofuels

Asthma One consequence of indoor air pollution
Asthma is at epidemic proportions in the U.S. Affects 20 million each year It attacks the respiratory system, causing wheezing, chest tightness, coughing, shortness of breath Acute attacks are sudden and can kill Substances that trigger asthma: dust, animals, mold, secondhand smoke, swimming pool chlorine, gases, etc. Asthma costs $11 billion and kills over 3,800/year in the U.S.

Worms, anyone? Asthma is more common in developed countries
Even though developing nations have more indoor air pollution Frequent parasitic worm infections stimulate anti-inflammation in the immune system Protecting people against allergic diseases like asthma Developed nations do not have worms and lack protection Instead of getting worms, identify the molecules that induce protection and put them in vaccines

Toxicology The link between hazardous substances and health problems is hard to establish A statistical correlation can be established between exposure and adverse effects Toxicology: the science that studies the impacts of toxic substances on human health It investigates the relationships between substances and environmental or health problems

Disaster risk More than 200 million/year are affected by natural disasters Needing emergency relief efforts, help, and reconstruction Costs $45 billion/year (2000s) Much death and misery can be avoided through disaster risk reduction strategies Living with Risk: A Global Review of Disaster Reduction Initiatives (2004) Applies concepts of hazards, risks, and risk assessment to natural disasters Gives policies for guiding and monitoring risk reduction

The Hyogo Framework for Action (2005)
168 country delegates met in Kobe, Japan The World Conference on Disaster Reduction Five priorities for risk reduction Make disaster risk reduction a priority Know the risks and take action Build understanding and awareness: using knowledge, innovation, and education Reduce risks Be prepared and ready to act: strengthen disaster preparedness for effective response

Risk assessment Society still faces hazards and their risks to health
We need to know about and evaluate these risks Diseases in developing countries require responses out of humanitarian concern Treating the sick will continue if prevention is ignored Governments get information by evaluating risks Risk assessment: the process of evaluating risks associated with a hazard before taking action in a situation where the risk is present

Loss of life expectancy from various risks

Risk assessment Risk is expressed as the days of lost life expectancy
Risk can also be expressed as the probability of dying from a given hazard The annual risk of dying from a vehicle accident = 1.6/10,000 1.6 out of 10,000 who ride in a car will die Equal to 300 days of lost life expectancy Not many people make choices about hazards But risk assessment is important for public policy and environmental regulation

Risk assessment by the EPA
Risk assessment began in the 1970s to understand the cancer risks of pesticides and other chemicals It is now a highly science-based methodology National Center for Environmental Assessment (NCEA) The EPA’s lead agency for risk assessment Risk assessment for human health has four steps Hazard assessment Dose-response assessment Exposure assessment Risk characterization

Hazard assessment: is this really a hazard?
Hazard assessment: the process of examining evidence Linking a potential hazard to its harmful effects Historical data are often used to calculate risks A link may not be clear due to a time delay between exposure and effect An epidemiological study tracks how a sickness spreads Are people exposed to a hazard sicker than the unexposed? Animal testing: uses animals to determine what might happen Uses hundreds of animals (mice) over years at high costs

Animal testing

Objections to animal testing
Rodents and humans may have different responses to a chemical Doses given to animals are much higher than humans are exposed to Some people are opposed for ethical reasons All chemicals shown to be human carcinogens are also carcinogenic in test animals

Just test people? Chemical manufacturers used to pay people to test products They are less expensive than animal testing A National Academy of Sciences panel stated this was unjustifiable The EPA banned such tests The Bush administration pressed to allow testing A 2006 EPA ruling allowed testing to restart But forbids testing on children or pregnant women The Natural Resources Defense Council is suing The Obama administration may stop this testing

Obtaining information on a chemical
The chemical or process can provide information What are its physical or chemical processes? How does it induce cancer? A weight-of-the-evidence approach: one approach to determining the carcinogenic potential of a chemical Descriptors used in its conclusions include that a chemical “is likely to be carcinogenic to humans” Hazard assessment tells us we may have a problem

Dose-response and exposure assessment
The relationship between the chemical concentrations (dose) and responses’ incidence and severity is analyzed When a link is shown between exposure and ill effects Children are growing and more vulnerable Dose-response assessment: a linear response determines an acceptable level of exposure Projections are made about numbers of potential cancers Exposure assessment: exposed groups are identified The dose, time, and origin of exposure are determined

Risk characterization: what does the science say?
Risk characterization: pulls all information to determine risk and its uncertainties Science informs the risk manager Summaries include data and methods, limitations Risk: the probability of a fatal outcome due to the hazard The Clean Air Act (1990) directs the EPA to regulate chemicals with a cancer risk greater than one in a million The FDA uses this standard for food, drugs and cosmetics A limit: analysts work with available information But it’s never enough, which allows some imprecision

Public-health risk assessment
Until 2002, most risk assessment was a function of environmental regulation The new effort looks at all risk factors responsible for poor health and morality Of all diseases, how much is caused by this risk? Risk factors are chosen for special attention based on Potential global impact: a leading cause of mortality, etc. High likelihood of causality: trace causes and effects Modifiability: policies to decrease the factor’s impact Availability of data: reliable data must be available

The DALY A common currency is used to assess data
Allows comparisons between different types of risks DALY: disability-adjusted life year 1 DALY = loss of one healthy year of life Assesses a disease in terms of life lost or a disability Different countries have different risk factors Each risk factor calls for different solutions Scientific bases for risk factors are well-understood Strategies for cost-effective risk prevention exist There is broad agreement about the need for action

Risk management Risk assessment: scientific analysis of hazards and risks Risk management: falls to lawmakers and administrators Involves reviewing information about the hazard Deciding whether the evidence justifies regulations Public opinion plays a role in both Regulatory decisions hinge on Cost-benefit analysis: decisions can be very clear Risk-benefit analysis: benefits are not expressed in monetary terms Public preferences: some risks are tolerated; some aren’t

Risk perception The U.S. public’s concern about environmental problems is due to the fear of hazards to life and health Our lives are less hazardous than ever before Why do people protest nuclear energy, waste sites, etc? These hazards pose very small risks Risk perception: the intuitive judgments about risks Perceptions are not consistent with a scientific analysis of risk

Hazard versus outrage Perception is a matter of outrage, not hazard
Hazard: a concern for fatalities only Outrage: expresses many concerns Lack of familiarity with a technology (e.g., nuclear) Extent to which a risk is voluntary: people with a choice accept far greater risks Public impression of a hazard: accidents aren’t forgotten Overselling of safety without detailing risks Morality: obey a moral imperative, regardless of costs Fairness: why accept risk if another benefits?

Media’s role The public’s perception of risk is strongly influenced by the media Outrage is expressed better than hazards High outrage quotients: beef from Canada was prohibited when mad-cow disease was found in two cows But cigarettes kill 443,000/year in the U.S. and receive little media attention

Public concern and public policy
Public concern, not cost-benefit or risk-benefit analysis, drives public policy Congress sets the EPA’s funding priorities Which reflects the public’s concern Serious risks may get less attention than they deserve if public outrage is the impetus for public policy Environmental risks are seen as less important The public has more immediate issues Risk communication: important in educating the public Done by scientists, educators, government, not media

Risk communication Most effective communication starts with what people already know Finding what they need to know Tailoring the message to give people knowledge to make informed evaluations of risk Communication should involve dialogue among everyone Policy makers, experts, the public, other interested groups Public concern must be heard, understood, and responded to It reflects values and concerns that science could omit

The precautionary principle
Use of risk assessment has been attacked It does not adequately reflect uncertainty It is used when a chemical or process is already in use The burden of proof of harm falls on the regulators The precautionary principle: where an activity threatens harm to humans or the environment, precautionary measures should be taken even if some cause-and-effect relationships are not fully known Proponents of the activity, not the public, should bear the burden of proof

Using the precautionary principle
It is well-established in Europe It is the basis for environmental laws It overlies some U.S. policies Pharmaceuticals and pesticides A substance is presumed guilty until proven innocent It is not permitted until tests prove it is safe It can implement stewardship in environmental health But should not be a blanket policy It can counter pressures from proponents Use it where the penalty for being wrong is great

Stewards of health Public-health ministries and agencies are the primary stewards of a country’s health and welfare Public policy should clearly reflect stewardship principles Put the public’s health and environment above the economic bottom line Governments can accomplish much in preventive health But they must nurture scarce resources The WHO focuses on reducing risk to promote health Health care providers are also stewards

Environmental Hazards and Human Health
CHAPTER 17 Environmental Hazards and Human Health Active Lecture Questions

Review Question-1 True or False: The existence of a hazard means that undesirable consequences will inevitably follow. a. True b. False

Review Question-1 Answer
True or False: The existence of a hazard means that undesirable consequences will inevitably follow. a. True b. False

a. Mortality; morbidity b. Morbidity; immortality
Review Question-2 ______ is the incidence of disease in a population, while ______ is the incidence of death in a population. a. Mortality; morbidity b. Morbidity; immortality c. Morbidity; mortality d. Immortality; mortality

______ is the incidence of disease in a population, while ______ is the incidence of death in a population. a. Mortality; morbidity b. Morbidity; immortality c. Morbidity; mortality d. Immortality; mortality

Review Question-3 The infectious disease caused by protozoan parasites of the genus Plasmodium and propagated by mosquitoes in tropical areas is a. tuberculosis. b. HIV. c. malaria. d. rotavirus.

The infectious disease caused by protozoan parasites of the genus Plasmodium and propagated by mosquitoes in tropical areas is a. tuberculosis. b. HIV. c. malaria. d. rotavirus.

Which of the following is not a physical hazard? a. smoking
Review Question-4 Which of the following is not a physical hazard? a. smoking b. hurricanes c. tornadoes d. earthquakes

Which of the following is not a physical hazard? a. smoking b. hurricanes c. tornadoes d. earthquakes

Which of the following is a risk associated with being poor?
Review Question-5 Which of the following is a risk associated with being poor? a. being underweight b. unsafe sex c. poor sanitation d. all of the above

Which of the following is a risk associated with being poor? a. being underweight b. unsafe sex c. poor sanitation d. all of the above

Interpreting Graphs and Data-1
According to Fig. 17-5, the continent most impacted by tuberculosis is a. North America. b. Asia. c. Australia. d. Africa.

Interpreting Graphs and Data-1 Answer
According to Fig. 17-5, the continent most impacted by tuberculosis is a. North America. b. Asia. c. Australia. d. Africa.

Interpreting Graphs and Data-2
According to Fig. 17-6, the number of days of lost life expectancy due to alcoholism is approximately a. 1,000. b. 2,000. c. 3,000. d. 4,000.

Interpreting Graphs and Data-2 Answer
According to Fig. 17-6, the number of days of lost life expectancy due to alcoholism is approximately a. 1,000. b. 2,000. c. 3,000. d. 4,000.

Thinking Environmentally-1
The following is a statement of the ______ principle: “Where an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if cause-and-effect relationships are not fully established scientifically.” a. causal b. precautionary c. measured d. environmental

Thinking Environmentally-1 Answer
The following is a statement of the ______ principle: “Where an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if cause-and-effect relationships are not fully established scientifically.” a. causal b. precautionary c. measured d. environmental

Thinking Environmentally-2
All of the following are in the top 10 risk factors for developed countries except a. tobacco use. b. high blood pressure. c. high cholesterol. d. high fruit and vegetable intake.

Thinking Environmentally-2 Answer
All of the following are in the top 10 risk factors for developed countries except a. tobacco use. b. high blood pressure. c. high cholesterol. d. high fruit and vegetable intake.

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