Environmental Health

Environmental health describes the effects of civilization, culture, personal habits, pollution, population growth, and travel on human health. It is a new science that measures a variety of factors leading to acquired and congenital diseases. Acquired diseases are illnesses people get from exposure to harmful chemicals, injurious activities, and pathogenic organisms. Congenital diseases are caused by genetic defects or factors that harm fetal development.

Throughout history people have witnessed the increase in human disease with the growth of agriculture and cities. It was not until the late nineteenth century that people had scientific explanations for the cause of the diseases. Urban growth and overpopulation are associated with higher incidences of communicable diseases spread by insects, rats, and humans. Agriculture also resulted in a host of new human diseases. A variety of diseases, such as influenza, measles, and smallpox, may have been developed from diseases originally found in agricultural animals.

In the past twenty years, plastics have become the most popular material for manufacturing a variety of products including automobiles, household goods, and medical devices. Plastics have replaced many traditional uses of glass, metal, and wood. They have permitted the development of fuel-efficient automobiles, lightweight airplanes, durable furniture, and safer food containers. With all these benefits comes a high environmental cost. Many scientists are discovering that many plastics leak pollutants capable of altering the body's endocrine system, which is responsible for body maintenance, growth, and reproduction.

The role of pollution and health was not well known to the public until the publication of Silent Spring, written by Rachel Carson in 1962. She alerted people to the health effects of pesticides and other pollutants on humans and wildlife. Many scientists supported her views, and this resulted in the formation of the Environmental Protection Agency by the U.S. government in 1970. The National Institutes of Health was later set up to look at other environmental health issues. This agency focuses on illnesses associated with household and work environments. In 1948 the World Health Organization was formed by the United Nations to deal with international environmental health problems.

Occupational health and wellness includes health issues related to the work environment. Some issues include injuries due to certain activities or illness due to handling certain chemicals. Ergonomics is a field of study that has linked conditions such as carpal tunnel syndrome to repetitive hand actions such as continuous typing on a keyboard or handling automobile parts on an assembly line.

Mental health is also a concern of public health agencies working in environmental health. Abuse, poverty, violence, and stressful work environments are associated with mental illnesses. Public health agencies seek ways of changing the social environment in attempts to reduce mental disease.

Today, scientists are continuously conducting research linking environmental factors to human illness. There are two types of environmental health research: experimental research and epidemiological research.

Environmental health experiments involve laboratory and field tests that show how an environmental factor can cause a particular disease. For example, animal experiments are showing that many types of water pollution will cause birth defects, cancer, and reproductive disorders. Epidemiological research techniques involve collecting data associating a particular illness to a certain activity or environmental factor. The data are gathered through surveys, public medical records, and field studies. Air pollution has been linked to increases in asthma and emphysema in epidemiology human studies. This was determined by comparing high rates of asthma and emphysema to increased levels of air pollution in an area.

Laws prohibiting smoking in many public areas are recent examples of government policy based on environmental health research. Food safety regulations controlling the amount of pesticides in foods are another example. The Environmental Protection Agency set laws that limit pollution to levels that do not cause illness to humans and wildlife.

see also Carson, Rachel; Disease; Epidemiologist

Brian R. Shmaefsky

Bibliography

Miller, Tyler. Environmental Science, Sustaining the Earth, 4th ed. Belmont, CA: Wadsworth Publishing Company.

U.S. Environmental Protection Agency. <www.epa.gov>.

U.S. National Institutes of Health. <www.nih.gov>.

World Health Organization. <www.who.int>.

Environmental Health

Environmental health is a two-way street. Our environment, in the largest sense, is the complex network of physical, chemical, biological, and ecological components that make up the natural world. How clean and unpolluted the air, water, and soil of this environment are can affect the health of human beings. On the other hand, the way people treat the environment in their professional, industrial, and recreational activities helps determine how clean and safe it will be. In short, the environment affects the health of human beings, and human beings affect the health of the environment. All of the issues that evolve out of the interaction between people and the environment fall under the umbrella of environmental health.

Governments, companies, and individuals have a responsibility to preserve and promote environmental health. Government agencies, like the Environmental Protection Agency (EPA), founded in 1970, regulate industry to limit pollution that can damage the environment. The EPA's mission is to protect public health and the quality of the natural environment. Legislation like the Clean Air Act, passed by Congress in 1970, protects air quality by setting standards of purity for the air circulated in homes, schools, and workplaces. Groups outside the government, such as the World Wildlife Foundation, also work to identify and control threats to the environment that will endanger the food, water, and homes of plants and animals.

Everyone must make choices about how and where to live. Whether people are watching television in their living rooms, working at an office, eating at a restaurant, swimming at a beach, bicycling in a park, or sitting in a classroom, they should be aware of the condition of the environment around them. Good environmental health means having a safe, clean environment so that everyone can be healthy and productive within it. This chapter discusses the many different risks that threaten the environment, including radiation, pesticides, and indoor and outdoor air pollution, as well as ways to protect the environment and those who live in it.

RADIATION

Radiation is energy, or emission of energy, in the form of waves or particles. Microscopic particles, called atoms, are the foundation on which all matter (all substances that exist as solids, liquids, or gas) is built. Each atom has a nucleus at its center. The nucleus contains smaller (nuclear) particles called protons and neutrons. If the number, position, or energy level of these nuclear particles changes, an atom becomes unstable, or radioactive. Unstable atoms, or atoms undergoing change, produce radiation.

Sources of Radiation

Radiation is everywhere. It occurs naturally in soil and water on Earth. It exists in outer space and inside human bodies. Since the natural sources exist everywhere, these sources are sometimes called background radiation. There are human-made sources of radiation, too. Radiation has been harnessed for use in science, medicine, and industry. X-ray technology, nuclear power plants, and some forms of electricity use radiation. According to the United States Environmental Protection Agency (EPA), 80 percent of radiation sources are natural and 20 percent are synthetic (human-made).

Radiation: Words to Know

Acid rain:

Rain with a high content of sulfuric acid.

Asbestos:

A mineral fiber.

Byproduct:

Something other than the main product that is produced in a chemical or biological process.

Carbon monoxide:

A colorless, odorless, tasteless gas that turns into carbon dioxide when it is burned.

Carcinogenic:

Cancer-causing.

Contaminate:

To infect something or make something unsafe for use.

Cosmic:

Relating to the universe in contrast to Earth.

Emission:

Substances released into the air.

Endocrine disrupter:

Manmade chemical that looks and acts like naturally-occurring hormones.

Environmental tobacco smoke (ETS):

The mixture of the smoke from a lit cigarette, pipe, or cigar and the smoke exhaled by the person smoking; also known as secondhand smoke.

Herbicide:

A chemical agent used to kill damaging plants, such as weeds.

Incinerator:

A machine that burns waste materials.

Industrial:

Relating to a company that manufactures a product.

Inert:

A chemical agent lacking in active properties.

Leaching:

The process of dissolving outward by the action of a permeable substance.

Lead:

A heavy, flexible, metallic element that is often used in pipes and batteries.

Microscopic:

Invisible without the use of a microscope, an instrument that enlarges images of tiny objects.

Nitrogen dioxide:

A gas that cannot be seen or smelled. It irritates the eyes, ears, nose, and throat.

Ozone layer:

The atmospheric shield that protects the planet from harmful ultraviolet radiation.

Particle:

A miniscule pollutant released when fuel does not burn completely.

Pesticide:

A chemical agent used to kill bugs.

Potassium:

A chemical element that is a silver-white, soft metal occurring in nature.

Radiation:

Energy or rays emitted when certain changes occur in the atoms or molecules of an object or substance.

Radon:

A colorless, odorless, radioactive gas produced by the naturally occurring breakdown of the chemical element uranium in soil or rocks.

Sulfur dioxide:

A toxic gas that can also be converted to a colorless liquid.

Synthetic:

Something that is man-made; not found in nature

Thyroid:

A gland that controls the growth of the body

Toxic:

Relating to or caused by a poison

Uranium:

A chemical element that is a silver-white, hard metal and is radioactive.

Volatile organic compound (VOC):

An airborne chemical that contains carbon.

Types of Radiation: Non-ionizing and Ionizing Radiation

Two major types of radiation are non-ionizing radiation and ionizing radiation. Non-ionizing radiation is the less potent (strong) form. It has the power to move atoms around, but not to chemically change (or ionize) them. Ionizing radiation, on the other hand, does have the power to chemically change atoms and it is this power that makes it a threat to humans and the environment. There are three major types of ionizing radiation. They are called alpha, beta, and gamma rays. (They can also be described as radioactive particles, or radiation.) Each of these sub-groups is distinguished from the others by the ease or difficulty with which it can penetrate (or enter) the human body.

ALPHA RADIATION. The ability of an alpha particle to enter the body can be blocked by paper or skin, but alpha particles can enter the body through an open wound and do harm. Airborne alpha particles that are inhaled can cause serious lung damage.

BETA RADIATION. Paper cannot block beta radiation from entering the body. Some beta particles would be deterred by skin, while still more powerful beta particles would require something the thickness of wood to prevent entry. If beta rays do find their way into the body, they can get into the bones and cause damage.

COMMON SOURCES OF RADIATION TO WHICH PEOPLE CAN BE EXPOSED

• computer terminal
• cosmic rays from outer space
• ingested food and water containing elements like potassium
• medical X ray
• radiation in cancer treatment
• radon gas (in the air)
• rocks and soil
• smoke detector
• television
• X-ray luggage inspection machine

GAMMA RADIATION. Gamma rays are the most powerful particles. Often appearing along with alpha and beta rays, these dangerous rays can break through paper, skin, and wood. A concrete wall would be needed to deflect gamma rays. If gamma rays penetrate the body, they can cause major damage to internal organs.

Radiation Risks

Most scientists agree that radiation can be carcinogenic (cancer-causing); indeed, the major health risk radiation poses is an increased risk of developing cancer. Other harmful effects that have been observed include genetic abnormalities in the children of parents who had significant exposure to radiation. Mental retardation, in particular, has been observed in children whose mother was exposed to a significant amount of radiation.

EXPOSURE TO RADIATION, OR THE DOSE (AMOUNT) OF EXPOSURE, IS MEASURED BY A UNIT CALLED A REM. THE UNIT OF MEASURE FOR SMALLER DOSES IS THE MILLIREM. A REM IS EQUAL TO 1,000 MILLIREMS. ACCORDING TO EPA SCIENTISTS, AN AVERAGE U.S. CITIZEN'S ANNUAL RADIATION EXPOSURE IS ABOUT 360 MILLIREMS PER YEAR.

RADON AND ITS THREAT TO HUMAN LIFE

While cosmic rays represent some 8 percent of human exposure to natural radiation, EPA scientists suggest that radon accounts for an over-whelming 55 percent of human exposure to natural sources of radiation.

Produced by the decay of radioactive uranium (a chemical element) widely found in soils around the planet, radon gas has no color, taste, or odor. Radon travels up from the ground to seep into the foundation of a school, home, or other building. Once inside a building, airborne radon can become a threat to human health. If unhealthy amounts of radon are inhaled, it can damage the lungs and cause lung cancer. Scientists believe radon is second only to smoking as a cause of lung cancer, with thousands of lung cancer deaths in America each year thought to be the result of radon exposure.

Exposure to radioactive elements in the ground, such as thorium and potassium, can vary depending on where a person lives since the composition of land varies in different places. Exposure from cosmic radiation that is discharged into the atmosphere from outer space can also vary by location. Places that are at a higher elevation have thinner atmospheres and less protection from cosmic radiation. Locations that are closer to sea level have a bigger buffer zone and are less susceptible to cosmic radiation.

The Food and Drug Administration (FDA) and EPA insure that strict guidelines are followed for medical procedures involving radiation. The personnel, equipment, and facilities involved all have to meet certain standards to insure that radiation is managed as safely as possible. The Nuclear Regulatory Committee (NRC) has made tougher rules to govern construction, maintenance, emissions, and operations of nuclear power plants to decrease the risk of dangerous nuclear accidents. Stronger rules have also been developed for disposal of the radioactive waste, which is the byproduct of medical, scientific, and industrial uses of radiation.

What to Do About Radiation Exposure

Even with federal agencies monitoring radiation risks and working to control dangerous exposure to human populations and the environment, people still can't avoid radiation altogether. But precautions can be taken to limit exposure. When doctors recommend getting an X ray, people should not be afraid to take a few moments to talk about the risks versus benefits. Also, people in any community should be encouraged to get homes or schools tested to find out if the radon levels are acceptable.

There are three key strategies to limiting radiation exposure:

1. Time spent near an identified source of radiation should be limited.
2. Distance from an identified source of radiation should be kept; more distance means less exposure.
3. Identified sources of radiation should be shielded, keeping them out of or away from the body where they can do damage; for example, cracks in pipes and foundations should be repaired to block radon from getting into the air of homes.

FEDERAL AGENCIES WORKING TO LIMIT RADIATION EXPOSURE

Environmental Protection Agency (EPA)

Nuclear Regulatory Committee (NRC)

Department of Health and Human Services (HHS)

Department of Energy (DOE)

Department of Defense (DOD)

Department of Transportation (DOT)

Occupational Safety and Health Administration (OSHA)

Concerns about radiation in one's environment can be addressed by writing to state legislators to find out what is being done to correct or prevent a problem. Individuals can stay up to date on environmental issues so as to know what the latest studies say about sources of radiation in the everyday environment, such as computers and television. More information helps to make smarter choices about what to do, or not do, to limit exposure to dangerous sources or levels of radiation.

PESTICIDES

Human beings rely on a wide range of plants and animals for food. The majority of what people eat is grown or raised on the land, or from the waters, around the Earth. Plants or animals that interfere with or destroy human agricultural or livestock efforts are called pests. Animals, particularly insects and rodents, that can cause damage to human homes, lawns, food, and sanitation are also called pests. Pesticides are the products, usually chemically based, that are used to fight or kill these pests.

Common Types of Pesticides

Pesticides are used in agriculture on a large scale. Powerful chemical agents that deter a harmful weed or pest might be sprayed over large areas

of crops. On a smaller scale, individuals use pesticides to protect their homes and yards. Pesticide products can be bought in many forms including sprays, liquids, sticks, powders, crystals, balls, and foggers. Products that are commonly used to control pests around the house include insecticides (insects), termiticides (termites), rodenticides (rodents), fungicides (fungi, such as mold), and disinfectants (germs that can cause disease).

Pros and Cons of Pesticide Use

The use of pesticides is surrounded by controversy. Pesticides serve an invaluable function in protecting the crops and livestock that are vital to people's food supply. Pesticides can also help defend people's homes against germs and unsanitary and destructive pests. On the other hand, some pesticides contain and spread chemicals, which are toxic (poisonous), or even fatal, if they are consumed by human beings.

Each pesticide contains an active chemical ingredient that is targeted to kill a specific plant or animal pest. But these ingredients are surrounded, or carried, by chemical agents referred to as inerts. They are called inert (meaning lacking in active properties) because they do not have an active effect on the targeted pest. The problem is that inerts can be toxic to other animals or plants with which they come into contact. Some of these inerts are so toxic that, to insure public safety, the recommended usage of the pesticide is limited to mere ounces per acre of land.

Pesticide Risks in Agriculture

Although pesticides are a relatively cost-effective way to protect crops and livestock from damage or destruction, the potential health risks (and the costs that might be generated by them) also need to be considered. Aerial (air) or ground applications of pesticides are hard to control because herbicides (chemical agents used on damaging plants, such as weeds) can drift onto unintended areas.

CONTROLLING PESTICIDE USE

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was passed in 1947 to establish more controls over pesticide use. In 1972, the Federal Environmental Pest Control amendment further expanded standards for products and procedures used in pest management. This amendment introduced the following controls:

• It is illegal to use pesticides in an amount or manner other than what is specified on the product label.
• There will be heavy fines and/or imprisonment for improper pesticide use.
• There must be a distinction between general-use and restricted-use pesticides.
• State certification is required for restricteduse pesticides.
• Environmental Protection Agency (EPA) is required to investigate pesticide manufacturing plants.
• Registration is required of all pesticides by the EPA.
• Scientific research is required to confirm a product's effectiveness on killing targeted pests and to confirm no risks to people, other plants, and other animals (assuming the product is used as directed).

Methods used to try to control this drift include applying pesticides closer to the ground; waiting for wind to be at a minimum when spraying; using spray nozzles that tightly focus the outgoing stream of pesticides; and adding thickeners to pesticides to help focus active ingredients toward the intended targets. Pesticide users also have to be careful to remove contamination from the sprayers before using them again. Tobacco, grapes, tomatoes, garden vegetables, and fruit trees are particularly vulnerable to certain pesticides used on other crops. The remains left in a sprayer from a previously used pesticide can harm these crops.

The federal government has set standards that the workers, equipment, and procedures involved with pesticide use in industrial agriculture have to meet. These standards help to protect workers, crops and livestock, and the public—the ultimate consumers of the food—from the health risks of pesticide contamination or exposure.

Protection from Pesticides

There are steps everyone can take to protect against the known (and potential) health risks of pesticide use or exposure.

• After pesticide is used on an area, it must be aired out.
• One can investigate and use non-chemical alternatives to pesticides.
• Pest control companies should be screened before being hired to work in the home.
• Pesticides must be stored carefully.
• Pesticides must be disposed of properly.
• Pesticides must not be applied or disposed of in streams or areas where wildlife drink and feed. (Waste can travel so it's important to be aware not only of the immediate location, but the areas and waterways it might be connected to, or drain into.)
• The Internet, science teachers, and the media can help to keep the public educated and updated on environmental issues.

OUTSIDE AIR POLLUTION

A major concern of environmental health is the quality of the air people breathe. There are both natural and synthetic processes that decrease air quality, or cause air pollution. Following is a breakdown of some of the major areas of concern.

Acid Rain

Beginning in the 1970s, there has been growing concern about the problem of acid rain. Acid rain is rain with a high content of sulfuric acid, which is produced when sulfur dioxide combines with hydrogen. Sulfur dioxide is released from natural sources, such as volcanoes, sea spray, and rotting vegetation. Burning fossil fuels such as coal and oil also produces it. Once released, the sulfuric acid mixes with hydrogen, a gas that is already in the atmosphere. The resulting sulfuric acid falls back down to the earth as a pollutant, acid rain.

Acid rain poses health risks to people and nature. The danger for people is respiratory (breathing) problems such as asthma, dry coughs, headache, and eye/ear/nose/throat irritations. Another danger of acid rain is that it contains the remains of toxic metals. When acid rain falls, toxic remains can be absorbed by fruits, vegetables, and livestock and passed on to human consumers. Consumption of these toxic metals, such as mercury for example, can lead to brain damage, kidney problems, and even death.

The sulfuric acid in acid rain is a particular threat to forests and soils. Sulfuric acid competes with trees for vital nutrients, limits their hardiness to withstand cold temperatures, and triggers unhealthy growing cycles. Sulfuric acid also has a corrosive, or damaging, effect on buildings and statues.

VOCs (volatile organic compounds)

In science, something that can easily become airborne is called volatile. Chemicals that contain carbon, a fundamental element of all living organisms, are called organic. Volatile organic compounds (VOCs) are elements with both of these features.

VOCs are released when fuel, including gasoline, oil, wood, coal, and natural gas, is burned. They are also found in commonly used solvents, paints, and glues. The exhaust from cars is a big source of VOCs.

VOCs have been linked to serious health risks, such as cancer, but they are known mostly for their role in forming smog. Smog is a chemical haze, or fog, that is made heavier and darker by smoke and chemical fumes. It occurs when ultraviolet radiation from the sun comes into contact with atmospheric pollution.

Carbon Monoxide

Carbon monoxide is a colorless, odorless, tasteless gas that turns into carbon dioxide when it is burned. Produced by burning gasoline, natural gas, coal, oil, or other materials, carbon monoxide cripples the flow of oxygen to cells and tissues that cannot function without it. People who suffer from respiratory or circulatory problems are especially vulnerable to health problems from exposure to carbon monoxide.

Sulfur Dioxide

Sulfur dioxide is a toxic gas that can also be converted to a colorless liquid. It is produced when coal, oil, or sulfur is burned. A key ingredient in sulfuric acid, sulfur dioxide is also used in processes such as bleaching, preservation, and refrigeration. It is used heavily in generating paper and metal. Sulfur dioxide ranks as one of the most significant causes of air pollution, particularly in industrial areas.

Lead

Lead is a heavy, flexible metallic element that is often used in pipes and batteries. It is also

an ingredient in some gasoline and paint. Sources of lead in the environment include leaded gasoline, house and car paint, metal refineries (smelters), and the production of lead storage batteries. Lead can cause severe damage to the human brain or nervous system, particularly in children. It can also cause digestive problems, and some chemicals that contained lead have been shown to cause cancer in animals.

Lead-based paint can lead to serious health problems. Dust and chips can crack off the paint in tiny particles, but even a small amount of lead ingested into the system of a child or pregnant woman can have a serious impact. If a child swallows or inhales lead, it can cause learning disabilities and disorders of the nervous system. Adults who ingest high levels of lead may experience high blood pressure, headaches, digestive problems, pain in joints and muscles, and other health problems. In 1978, lead-based paint was banned because of the threat to public health, but homes and schools built before 1978 may still have lead-based paint in or on them. Lead-based gasoline is also in the process of being phased out.

Environmental Effects of Outside Air Pollution

According to the Environmental Protection Agency (EPA), 60 to 70 U.S. metropolitan areas—that are home to some 62 million Americans—do not meet air quality standards for one or more air pollutants. Total emissions of nitrogen oxides (NOx) that are thought to damage the environment have increased by 14 percent since 1970. Cars and power plants are large contributors to this problem. Chemicals that threaten the Earth's ozone layer (the atmospheric shield that protects the planet from harmful ultraviolet radiation) are another concern. If the integrity of the ozone layer is compromised, the Earth will be exposed to ultraviolet radiation and this could result in increases in the occurrence of skin cancer and cataracts (an eye disorder), as well as damage to crops and plankton (the tiny plants and animals that float in a body of water and are what fish eat). The reduction of plankton and plant life will lead to an increase in carbon dioxide levels. In fact, worldwide levels of carbon dioxide have increased by 8 percent since 1972. Although great strides have been made to control air pollution that is toxic to people and the environment, there is still a long way to go.

What to Do to Protect Against Outside Air Pollution

All the potential dangers in the air cannot be avoided, but it is important to try to limit exposure to pollutants or unhealthy levels of pollutants.

• Playing outside on days when the air quality is at an unhealthy level is not advisable (local television and radio stations generally report this).
• Homes and schools should be tested for lead-based paint.
• Lead-based paint must be properly contained or removed from homes and schools.
• Carpools can be coordinated to get to and from activities, thus cutting down on car fumes.
• People can get involved in recycling and pollution-control efforts in their communities.

INDOOR AIR POLLUTION

The quality of the air people breathe in outdoor activities is a concern, but the quality of the air indoors is an equally, possibly even more, significant issue of environmental health. Research suggests that Americans spend 90 percent of their time indoors. And, in recent years, scientific studies have revealed that the air in homes and other buildings may contain even more pollutants, or higher levels of pollutants, than the air outdoors. These severe levels of indoor air pollution have been found even in highly industrial metropolitan areas, where one might automatically assume that air pollution risks would be greater outdoors than indoors. In light of this research, organizations like the Environmental Protection Agency are taking a closer look at what's happening with air quality inside homes, schools, and offices. Some of the key threats to air quality, and in turn to human health, are discussed below.

Tobacco Smoke

Environmental tobacco smoke (ETS) is the mixture of the smoke from a lit cigarette, pipe, or cigar and the smoke exhaled by the person smoking. ETS exposure is sometimes referred to as passive smoking or secondhand smoking. Even though the affected person is not actively lighting up and inhaling, enough smoke is being breathed into the person's lungs to have a negative impact on his or her health.

ETS contains over 4,000 chemical compounds. According to the EPA, over 40 percent of these chemicals are known to cause cancer in humans or animals, and many of them are strong irritants. A 1992 EPA study (Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders) evaluated the risks of ETS to nonsmokers and concluded that ETS posed a significant health threat to nonsmokers, putting them at risk for a wide range of irritations and illnesses. Most significantly, the study indicated that, annually, exposure to ETS is responsible for about 3,000 lung-cancer deaths among nonsmoking adults.

The 1986 Surgeon General's Report concluded that physically separating smokers from nonsmokers in a home or office—by putting the smokers in a separate room—did not entirely eliminate a nonsmoker's exposure to ETS. Nonsmoking regulations have been put into effect in many offices and public areas to protect nonsmokers from the harmful effects of secondhand smoke. Nevertheless, individuals have to be conscientious about their exposure to ETS in private homes and unregulated public areas.

Radon

Radon is a colorless, odorless, radioactive gas produced by the naturally occurring breakdown of the chemical element uranium in soil or rocks. Radon gas is released into the air when radon is broken down. It can get into a home through dirt floors, cracks in concrete walls and floors, floor drains, and sumps (underground drainage system, or cesspool). When radon gas enters and becomes trapped in a home, it can build up to dangerous levels and pose threats to human health. In rare cases, building materials used in a home give off radon. Radon can also surface in well water.

REPORTED HEALTH EFFECTS OF ETS (SECONDHAND SMOKE) EXPOSURE

• There is an increased risk of lung cancer in nonsmoking adults.
• ETS endangers, or damages, the respiratory health of hundreds of thousands of children each year.
• Parents who smoke in the presence of their children increase the risk for the children to develop lower respiratory tract infections such as bronchitis.
• Infants and children exposed to ETS by smoking parents more frequently have problems with coughing, excess mucus, and wheezing.
• ETS annually causes between 150,000–300,000 lower respiratory infections in children under the age of eighteen months.
• Older children might experience reduced lung function due to ETS exposure.
• Asthmatic children are especially vulnerable to effects of ETS.
• Exposure to secondhand smoke can increase the number or severity of asthma attacks experienced by hundreds of thousands of young asthma sufferers each year.
• Each year, ETS might lead to the development of asthma in thousands of nonasthmatic children.
• The asthmatic condition of 200,000 to 1,000,000 children is worsened each year as a result of ETS exposure.
• ETS causes significant eye, ear, nose, and throat irritations.
• ETS may negatively affect cardiovascular (relating to the heart and lungs) health.

When inhaled, high levels of radon can cause lung cancer in people. It can also be unhealthy to swallow radon-contaminated water. But the most serious exposure is from breathing air with high levels of radon. Organizations like the Centers for Disease Control and Prevention, the American Lung Association, and the American Medical Association agree that radon causes thousands of lung-cancer deaths each year. There is also agreement that many of these deaths could be prevented by better controls on indoor air pollution. According to estimates by the Environmental Protection Agency, on average there are about 14,000 deaths caused by radon in the United States each year. Studies also suggest that smokers are especially vulnerable to health risks posed by radon.

Stoves, Heaters, Fireplaces, and Chimneys

Harmful pollutants, in the form of gases or particles, can be released into the air by combustion (or burning) processes that take place in the home. Poorly ventilated kerosene and gas space heaters, wood stoves, fireplaces, and gas stoves can release combustion products. Other sources include improperly installed chimneys and flues and cracked furnace equipment. Fireplaces and wood stoves, in particular, can backdraft (or draw) pollutants from the chimney into a room. Carbon monoxide and nitrogen dioxide particles are generated by combustion.

Carbon Monoxide

A colorless, odorless gas, carbon monoxide makes it difficult for the body to circulate oxygen. In large amounts, carbon monoxide can lead to unconsciousness and even death. Smaller amounts result in headaches, dizziness, nausea, disorientation, and fatigue. People who suffer from heart disease might experience increased chest pain when exposed to carbon monoxide. Beside people with chronic heart diseases, the negative health effects brought on by carbon monoxide exposure particularly endanger infants and the elderly.

Nitrogen Dioxide

Like carbon monoxide, nitrogen dioxide is a gas that cannot be seen or smelled. It irritates the eyes, ears, nose, and throat. Human exposure to large quantities of nitrogen dioxide (or repeated exposure to lower quantities over a long period of time) can cause shortness of breath or lead to increased risk of respiratory infection. Some studies with animals indicate that nitrogen dioxide exposure can lead to lung diseases such as emphysema. Adults and children who suffer from asthma or other breathing disorders are especially vulnerable if exposed to nitrogen dioxide.

Particles

Particles are released when fuel does not burn completely. They can enter and bury themselves in human lungs, where they can cause irritation or damage. Particles also provide a hanger for other airborne pollutants (such as radon, for example) to latch onto and use to gain entry into human lung tissue. Cancer-causing radon, for example, could latch onto a particle produced by incomplete combustion. The radon would be inhaled with the particle and end up lodged deep in the human lungs where it could lead to cancer.

Household Products

Many household products contain organic (carbon-containing) chemicals. These products can release polluting organic chemicals or compounds while in use or storage. Products with organic chemical ingredients include paints; varnishes; wax; many disinfecting, degreasing, or cosmetic agents; and fuels. According to the EPA, twelve common organic pollutants have been found in the air in homes at levels two to five times higher than the levels at which they were found in the air outside homes (even in industrial areas). EPA studies also indicate that people using household products, as well as others, can be exposed to high levels of chemical pollutants. These chemical pollutants also linger in the air even after the product is no longer being applied.

Evidence is still being gathered as to the short- and long-term health risks of organic chemicals released by household products, and what concentrations or lengths of exposure are dangerous. Findings to date suggest that health risks include respiratory tract irritation, headaches, dizziness, visual disorders, and impaired memory. A larger concern is that many organic compounds have been shown to cause cancer in animals and are suspected, or proven, to be cancer-causing agents in humans. While research continues, household products should be used in well-ventilated areas and according to label instructions.

Asbestos

A mineral fiber, asbestos was frequently used to insulate or fireproof building materials until studies began to reveal asbestos-related health dangers. The EPA has banned some asbestos products and manufacturers are limiting their use of asbestos products, but some older homes and buildings built before 1978 were built with asbestos-based materials. In these buildings, asbestos can appear in pipe and furnace insulation materials, shingles, textured paints, and floor tiles.

Asbestos fibers are dangerous when airborne. They can become airborne if asbestos-containing materials are cut, sanded, or disturbed in removal or remodeling efforts. Once airborne, tiny asbestos fibers can be inhaled and accumulate in human lungs, where they can cause cancer, meso-thelioma (cancer of chest and abdominal linings), and asbestosis. Asbestosis creates scar tissue in the lungs that cannot be repaired; this can be a life-threatening condition. Asbestos-related diseases have mostly been traced to high exposure on the job, or exposure to asbestos particles carried into a home on clothing and equipment by someone working a job involving high exposure to asbestos.

Lead

Like other chemicals that pose health risks, lead cannot be seen, smelled, or tasted. Since it does not break down naturally, trained professionals must physically remove lead sources from the environment they are polluting. Before

the health risks of lead were known, lead was used in paint and water pipes. Today, most house paint is almost entirely lead-free, and lead-based materials are not used in household plumbing systems. On the other hand, homes and buildings built before 1960, and even as late as 1978, may contain lead-based paint. Lead-based paint in good condition usually does not pose a risk. But lead-based paint in bad condition can cause serious problems.

Lead gets into the body from breathing contaminated lead dust from air, swallowing contaminated water, or ingesting lead-filled paint chips or soil. Problem sites can include window frames, walls, doors and doorframes, stairs, railings, banisters, and any objects or surfaces covered in lead-based paint. Hobbies such as refinishing furniture and making pottery or stained glass can produce lead remains. Workers who have jobs in construction, demolition, radiator repair, or handling batteries could carry dust from their job sites back to their homes. Soil that contains lead can also be easily tracked into the house from outdoors.

In spite of the growing awareness about the dangers of lead poisoning, the Centers for Disease Control and Prevention report that one in eleven American children has a high level of lead in their blood. Children can have especially serious health problems if they consume lead, causing learning disabilities, decreased growth, hyperactivity, and even brain damage. Pregnant women are also especially sensitive to lead-related problems.

Pesticides

Surveys have shown that at least one indoor pesticide product is used in about 75 percent of U.S. homes each year. Insecticides and disinfectants are used even more. Indoor exposure is responsible for 80 percent of an average American's exposure to pesticides, according to a recent study. The study also found that the air content of average homes could have high levels of as many as twelve different pesticides. While this research attributes 80 percent of an average American's pesticide exposure to indoor sources, actual pesticide use in the home does not accurately account for all the pesticides that are found in the air in a home. Contaminated air, water, or soil that is brought into a household from the outdoors can also contribute to the pesticide content in the home. Other contributors are stored pesticides, and household objects and surfaces where pesticides can accumulate, then later be released.

According to the 1990 records of the American Association of Poison Control Centers (AAPCC), 79,000 children were exposed to, or poisoned by, a household pesticide in that year. The AAPCC also reported that in almost 50 percent of households with children under age five, at least one pesticide product was stored in a place children could access.

When people use pesticides (insecticides, disinfectants, repellants, and rodenticides) in and around their homes, they should always keep in mind that how and where they handle, apply, and dispose of pesticides might also affect the environment and other people, pets, plants, and wildlife.

Effects of Indoor Air Pollution

There can be both short- and long-term effects from exposure to indoor air pollution. Short-term or immediate effects include irritations of the eyes, nose, and throat; headaches; dizziness; and fatigue. Symptoms of diseases such as asthma might appear not long after a single, or repeated, exposure to indoor air pollutants. Other, more serious, health problems, such as respiratory diseases, heart disease, and even cancer, may surface a long time after a person's first exposure to an indoor air pollutant (or several indoor air pollutants). These serious, even fatal, diseases might also appear after a person has been repeatedly exposed to the same air pollutants over a long period of time.

What to Do to Protect Against Indoor Air Pollution

All the pollutants can't be eliminated from the air people breathe, nor can there be an avoidance of some exposure to them. It is possible, however, to have protection against exposure to indoor air pollution, or at least against dangerous levels of indoor air pollution, by taking some basic steps:

TOBACCO SMOKE. Tobacco smoke exposure can be reduced or eliminated by:

• not smoking
• discouraging smoking in the home
• discouraging people from smoking around infants and children

RADON. Exposure to radon can be controlled by:

• being sure all living space is properly ventilated
• encouraging parents/teachers to have the air circulating at home and in school checked for radon levels and other pollutants
• having well water tested, and if necessary treated, for high levels of radon
• taking time to identify the sources of air pollution problems
• keeping windows open when painting to control, or prevent, problems
• encouraging everyone at home or at school who works on painting or soldering projects or hobbies to work carefully and clean up thoroughly
• investigating products and services to improve ventilation and clean air
• keeping living and working spaces as clean and dust-free as possible

STOVES, HEATERS, FIREPLACES, AND CHIMNEYS. Pollution from stoves, heaters, fireplaces and chimneys can be eliminated or reduced by:

• following instructions when installing and using unvented, fuel-burning space heaters
• having exhaust fans over gas cooking stoves and adjusting burners correctly
• making sure wood-stove emissions meet EPA standards
• selecting a stove that is the correct size for the space in which it will be used
• arranging the annual inspection of central air conditioning and heating systems
• repairing damaged or broken parts immediately

HOUSEHOLD PRODUCTS. With household products it is advisable to:

• read and follow label instructions
• safely dispose of chemicals that are old or no longer used
• buy household products on a need-only basis so a lot of chemicals aren't stored
• limit exposure to paint strippers, adhesive removers, and aerosol spray paints
• ask dry-cleaners to remove as much as possible of the perchloroethylene (active chemical agent used in dry-cleaning)

ASBESTOS. Because of asbestos's hazardous nature one should:

• not tamper with asbestos material that is in good condition in the home
• avoid cutting, ripping, or sanding asbestos-based materials
• have a professional contain or remove asbestos in the home

LEAD. To prevent problems related to lead, it's important to:

• get tested for lead poisoning
• use a solution of water mixed with powdered dishwasher detergent to wash floors and windowsills
• be sure children are not chewing on objects or surfaces covered with lead-based paint
• get professional help to remove lead paint from the home
• have water tested for dangerous levels of lead
• run cold water for thirty to sixty seconds if it has not been used in over two hours to give pipes a chance to clear before drinking or cooking
• not store food or liquid in lead crystal or in pottery with high lead content

PESTICIDES. For protection from pesticides, it's important to:

• read and follow exactly all label instructions
• never use a large amount of a pesticide, or use it more frequently than what is indicated
• limit exposure to moth repellants
• keep living space clean and well ventilated
• avoid direct physical contact with pesticide being used
• cover exposed human/pet food and water containers before applying pesticides

ENDOCRINE DISRUPTERS

Most living animals, including human beings, have an endocrine system. The endocrine system—made up of glands such as the pituitary gland and thyroid gland—functions by releasing hormones into the bloodstream. Hormones are like packets of information, which are sent to different cells to stimulate specific reactions or processes that help to keep the body functioning properly. Some man-made chemicals look and act like these naturally-occurring hormones. These chemicals are called endocrine disrupters because, when they get into the bloodstream of a person or animal, they can prevent the real hormones from doing their jobs. Endocrine disrupters are synthetic chemicals or chemical byproducts. They are fat-soluble, which means they dissolve in fat, not water, and therefore remain in the body longer. Most endocrine disrupters come from pesticides or industrial chemicals.

WHAT DOES THE ENDOCRINE SYSTEM DO?

Body functions affected by the endocrine system in humans are:

body growth; organ development; metabolism; kidney function; body temperature; calcium regulation; blood pressure; reproductive cycles.

In addition to the above list, the following are also affected just in animals:

mating behaviors; migration; fat distribution; hibernation

What Endocrine Disrupters Do

Endocrine disrupters usually interfere with real hormones in one of three ways. They can be mimics, blocks, or triggers. Mimics imitate real hormones. The mere presence of these chemical imposters disturbs the body's delicate hormonal balance. When this balance is off, the body does not function properly. Blocks are endocrine disrupters that actually get in the way of real hormones. Hormones have to attach to a certain part of a cell, called a receptor site, to tell the cell what it needs to do to keep a particular organ or process running smoothly. Endocrine disrupters can block this information by attaching to a receptor site so that the real hormone cannot. With the endocrine disrupter in the way, the information the cell needs to function does not get through. Triggers do not just imitate or block real hormones; these endocrine disrupters actually give the body directions about what it should do. When the body responds to these signals, things go wrong because, unlike the real hormones, the endocrine disrupters do not know what they should be telling the body to do. The artificial triggers cause inappropriate growth, changes in metabolism, or other abnormal interactions that can create biological chaos.

Where Endocrine Disrupters Come From?

A wide range of synthetic chemicals and chemical byproducts developed for commercial and industrial purposes are suspected of being, or producing, endocrine disrupters. Many detergents, pesticides, plastics, and varnishes, for example, are made with or from endocrine disrupter chemicals. Through production and use of these products, endocrine disrupters are released into the environment where they can pollute food and water sources. Later, these artificial, hormone-disrupting substances can get into the bloodstreams of the people or animals who consume food and water from the contaminated sources.

Endocrine disrupters do not just come from environmental pollution. They can also be contained in synthetic drugs and be absorbed into a person's bloodstream when the drug is taken.

Most Common Endocrine Disrupters

The most common endocrine disrupters are known as environmental estrogens. Examples include PCBs and Dioxin. Environmental estrogens mimic the natural estrogens (female sex hormones) and androgens (male sex hormones), which control reproduction and sexual characteristics. Environmental estrogens have their biggest impact on fetuses (infants developing in a mother's womb). Once a baby is born, their sexual features are developed, but in the womb the sex hormones play a key role in shaping an infant's sexual makeup. The presence of artificial hormones in the mother's body can interfere with, or alter, the normal course of a fetus's sexual development.

Environmental estrogens have a particularly dramatic effect on males. Exposure to environmental estrogens in the womb can lead to a male being born with an unnatural amount of female sexual characteristics, or even a hermaphroditic condition, which is when a person has both male and female sexual features.

Sexual characteristics are not the only element that environmental estrogens can affect. Other biological features—such as bones, cardiovascular system, memory, and immune system—can be weakened in a male or female baby who is exposed to environmental estrogens in the womb.

DOCUMENTED EFFECTS OF ENDOCRINE DISRUPTERS

Polluted Species from the Great Lakes

The Great Lakes area is known to be a highly contaminated area, with particularly elevated levels of endocrine disrupters. Studies done on species from the Great Lakes area have revealed a range of abnormalities, such as the following:

• Low rates of egg production, abnormal enlargement of the thyroid gland, early mortality rates, and low reproduction rates have been seen in several fish species, especially salmon.
• Birds in the area (including bald eagles and herring gulls) that feed on these fish have demonstrated symptoms similar to those observed in the fish.
• Hermaphroditic fish (genetically male fish with female genitals) have been observed.

The Florida Everglades

A study of male alligators was conducted in Lake Apopka, Florida, which is situated near a nowclosed chemical processing plant. DDE, a byproduct of the pesticide DDT, was generated at this plant. The male alligators in this area were found to have abnormally small penises, while male alligators in other (nonpolluted) Florida regions had normal size genitalia. Scientists attribute the Lake Apopka alligators' condition to exposure to DDE.

DES

A prescription drug called diethylstilbestrol (DES) was produced in the 1940s. The drug, which contained a synthetic estrogen compound, was administered to women who experienced complications during their pregnancies. It was later discovered to cause problems in the daughters of the women. The daughters who had had fetal exposure to the drug had depression, decreased fertility, abnormal pregnancies, organ dysfunction, and increased occurrences of cancers, especially of reproductive organs.

The Risks Associated with Endocrine Disrupters

Many studies conducted on animal populations in chemically contaminated areas strongly suggest that endocrine disrupters are potent and frequent pollutants of our food and water sources. Abnormalities, particularly sexual

abnormalities, have been observed in the offspring of the animals that live, feed, and drink in these contaminated areas. Although similar studies have not been undertaken in human populations, many scientists are concerned that the risks of human exposure to endocrine disrupters might be significant.

Pesticides can get into food supplies directly or indirectly. They can be sprayed on crops, which people later consume. Industrial pollution releases endocrine disrupters into the environment, exposing fish, cattle, hogs, and poultry. If the fish and animals ingest the chemicals, they will be contained in their fat and later passed on to human consumers.

Scientists have also expressed concern about plastics and artificial materials used in food preparation and storage. They are concerned that a leaching process might take place. Leaching is when dangerous products found in plastics move from the plastics into the food in the container. Although it is in the early stages, recent research has shown that endocrine disrupters can leach out of plastic containers into the liquid they are holding. Similar concerns have been raised about tin cans. Research suggests that the coating a tin can is treated with might contain endocrine disrupter chemicals, which are able to leach into the can's contents.

Incinerators and other equipment that use combustion release endocrine disrupters into the atmosphere. Once released into the atmosphere, they pose a risk to human life and wildlife.

Drinking water sources must also be monitored carefully. Contaminated drinking water could also expose humans to endocrine disrupters.

The effects of exposure to endocrine disrupters are not always immediate. It may take awhile for symptoms to surface, or the effects and problems could show up in the next generation (meaning in the children of the person who was exposed).

What Can Be Done to Protect Against Endocrine Disrupters

The scientific community is pursuing research in the area of endocrine disrupters. Environmental groups like the World Wildlife Foundation are encouraging the government to crack down on industry's use of chemicals that are proven (or suspected) to be endocrine disrupters. And more testing needs to be done to determine other chemicals that are endocrine disrupters. While investigation and regulation of endocrine disrupters is taking place on a national scale, people can protect and educate themselves on an individual level, too. Some suggestions for limiting exposure to endocrine disrupters are to:

THE BLACK PLAGUE

Environmental health has been an issue since ancient times. Even in the earliest days of civilization, it became clear that infections could be produced and spread in certain environments. Bubonic plague, nicknamed "the Black Plague," which claimed 25 million lives in Europe from 1347 to 1532, is an example of an infectious disease made worse by environmental conditions. Unsanitary living conditions gave the fleas and rats that carried the disease access to homes, bedding, and food. As people realized how important the proper management of drinking water, food supplies, and sewage was, new methods were developed to combat contamination and pollution. In modern society, health problems are now more commonly thought to be lifestyle-related, rather than correlated to environmental causes. But health risks from the environment can be substantial even in a sophisticated, technologically advanced society. In fact, many of the modern processes and products themselves are responsible for creating a whole new range of environmental risks to be explored and controlled.

• limit fat and oil intake (since endocrine disrupters tend to accumulate in fats)
• avoid cooking, microwaving, and storing food in plastic or styrofoam containers
• use pesticide-free, organically-grown foods
• not handle pesticides
• investigate the origin of fish, poultry, and meat by asking the grocery store manager what the source is
• encourage local store owners and managers to purchase produce and animal-based products from waters, farms, and rangelands that have been tested for pollution and contamination
• get involved in antipollution efforts in your community
• write to state legislators to find out their views on key statewide environmental issues

FOR MORE INFORMATION

Books

Dolan, Edward F. Our Poisoned Waters. New York: Cobblehill, 1997.

Kahl, Jonathan D.W. Hazy Skies: Weather and the Environment. Minneapolis, Minn.: Lerner Publications, 1997.

Willis, Terri and Wallace B. Black. Cars: An Environmental Challenge. New York: Children's Press, 1992.

Wright, David. Facts on File Environmental Atlas. New York: Facts on File, 1998.

Young, Lisa. Pesticides. New York: Lucent Books, 1995.

Zike, Dinah. Earth Science Book: Activities for Kids. New York: John Wiley and Sons, 1993.

Zonderman, Jon. Environmental Diseases (Bodies in Crises). New York: Twenty-First Century Books, 1995.

Web sites

Children's Environmental Health Network. [On-line] http://www.cehn.org (Accessed August 19, 1999)

Earthforce. [Online] http://www.earthforce.org (Accessed August 19, 1999)

Environmental Health Coalition. [Online] http://www.environmentalhealth.org (Accessed August 19, 1999)

The Environmental Protection Agency's (EPA) site for students. [Online] http://www.epa.gov/students (Accessed August 19, 1999)

National Education Association Health Information Network. [Online] http://www.nea.org (Accessed August 19, 1999)