KEY TERMS
Concentrated animal feeding operations (CAFOs)
Consumer Product Safety Improvement Act
Environmental Protection Agency (EPA)
Polychlorinated biphenyls (PCBs)
Humans are designed by eons of evolution to live on the earth: to breathe the earth’s air, to drink the earth’s water, to eat the plants and animals that grow on the earth’s surface. People are adapted to the earth’s environment. While there is considerable variation in that environment in different parts of the planet, and while humans have found ways to live in many different climates and habitats, people’s health depends on the presence of these basic ingredients of life—air, water, and food. There are also natural phenomena in the environment that can harm human health: extremes of heat and cold, ultraviolet rays of the sun, toxic minerals and plants, and other living organisms, from pathogenic bacteria to predatory mammals.
Human beings are social creatures, dependent upon other people to help them navigate the earth’s environment. All humans in all parts of the world live in groups, from small bands of hunters and gatherers to the residents of teeming cities. When groups of people settle down to live together in one place, they change their shared environment: the larger the group, the greater the effect on the environment. Some of these changes may be made deliberately, to improve life for everyone; some are the inadvertent results of crowding, with harmful effects on people’s well-being.
Archaeological evidence shows that the earliest cities were designed with consideration for the health of their inhabitants. As early as 2000 B.C., cities in India, Egypt, Greece, and South America had devised ways of providing clean water and draining wastes. These ancient systems of water supply, drains, and sewers are the first evidence of public health measures: organized community efforts to provide healthy conditions for the population.
Ensuring a clean water supply and the safe disposal of wastes—functions that fall into the category of environmental health—are still among the most important responsibilities of government. Other environmental health functions necessary in industrial countries are measures to ensure clean air and safe food. All these concerns arise because of the human tendency to live in groups. Most people do not have the means or the desire to grow their own food, draw water from their own well, and dispose of wastes in their own yard. Because people live together in cities and suburbs, they rely on others to provide their food and water and to dispose of their wastes. Because there are so many people on earth today, and because of the prodigality of the modern lifestyle, the wastes people produce have unprecedented potential to pollute the air and litter the earth.
Role of Government in Environmental Health
Environmental health is clearly the responsibility of government. Many environmental exposures, such as air pollution, are beyond the control of the individual. Others can be avoided only at significant trouble and expense, for example, if people grow their own vegetables, or buy them from farmers whose agricultural methods they have inspected themselves. Governments ensure a healthy environment by various means, sometimes providing services directly, in other cases by setting standards and regulating how the services should be provided.
Traditionally in the United States, local governments have provided water for their citizens. They are required by law to meet standards set by state and federal governments. Local governments also traditionally provide sewage systems to dispose of wastes from individual households and to handle runoff from the land.
In the 1960s, Americans became increasingly aware that the environment was deteriorating. Lakes and streams were choked with sewage and chemical wastes that killed fish and other wildlife. Cities were overhung with smog. Citizens were outraged by news stories of neighborhoods poisoned by long-dormant toxic waste dumps. State and federal governments were pressured to assume more responsibility for the environment. In the late 1960s and early 1970s, many new laws set standards for air, water, and waste disposal. The first Earth Day, celebrated in the United States on April 22, 1970, marked the beginning of the modern environmental movement with coast-to-coast rallies and teach-ins. That year, the Environmental Protection Agency (EPA) was established to consolidate federal research, monitoring, standard-setting, and enforcement activities to achieve a cleaner, healthier environment in the United States.
Perhaps the most difficult environmental health issue people face today is the threat that human activities worldwide are changing the climate of the earth. The major concerns are depletion of the earth’s ozone layer and the accumulation of “greenhouse gases” in the atmosphere. These problems, both of which may significantly affect human health, transcend national boundaries. While the United Nations has sponsored international meetings on these issues and governments have signed treaties designed to bring the problems under control, there is no way of enforcing these agreements.
Identification of Hazards
A major role of the federal government in environmental health is to identify hazards in the environment and to set safety standards that must be met by industry and by state and local governments to protect people from these hazards. Both the identification of a substance as hazardous and the setting of standards are often difficult and controversial. The risks posed by most synthetic chemicals that are discharged into the environment by industrial processes or that are disposed of by consumers are unknown. Testing for potential harmful effects is expensive and time-consuming, and the choice of chemicals to test may be politically controversial. Even in cases where the health risk is obvious—such as the discharge of raw sewage into waterways or the air pollution caused by America’s dependence on the private automobile—local governments, industry, and even the average citizen may resist requirements to meet standards because of the expense and inconvenience of cleaning up the environment.
Radiation is an environmental health hazard that people tend to worry about only when it is artificially produced. However, all people are exposed to cosmic radiation in varying amounts depending on where they live, and natural radioactive materials are found in soils and rocks in many parts of the world. Radon gas, produced by the natural radioactive decay of uranium, is present in many homes, a fact that was recognized only in the mid-1980s. Prolonged exposure to radon is potentially a cause of lung cancer, although the risks from radon in the home are not well understood. Ultraviolet radiation from the sun is a significant cause of skin cancer and melanoma. There is no way these exposures can be regulated by government, except for some testing requirements concerning radon.
The discovery in the mid-1890s of x-rays, which could pass through flesh and reveal bones, aroused great public excitement and led to extensive human exposures before the danger was recognized. During the early decades of the 20th century, x-ray treatments were popular as cure-alls for a variety of ailments, and radioactive ingredients were added to patent medicines. The first alarm was raised in the mid-1920s, with the deaths from kidney and bone disease of a number of workers who painted watch dials with radium so they would glow in the dark. They had been touching the paintbrushes to their lips to sharpen the points, thereby ingesting toxic quantities of the chemical. Then in 1932, a rich, socially prominent businessman died agonizingly from the same mysterious ailment, which was diagnosed on autopsy as radium poisoning. He had been dosing himself over a 5-year period with hundreds of bottles of Radithor, a radium-containing patent medicine. The publicity surrounding the Radithor scandal led to strengthened Food and Drug Administration (FDA) powers to regulate patent medicines as well as specific limitations on radioactive pharmaceuticals.1
Evidence that chronic exposure to low levels of x-radiation caused cancer came from epidemiologic studies that began in the 1930s. One study compared death rates of radiologists with those of other medical specialists and found that the average age at death for radiologists was five years younger than that of other specialists.2 Radiation’s damaging health effects were confirmed by long-term follow-up studies of survivors of the atomic bombings of Hiroshima and Nagasaki, Japan, which ended the Second World War. The incidence of leukemia and other cancers was significantly increased among these people. Today, medical and dental x-rays constitute the largest source of nonbackground radiation exposure, although equipment has been continuously improved to reduce the hazard. Since about one-third of the medical and dental x-rays that Americans receive are estimated to be unnecessary, patients are advised to question whether each exposure is essential.
That some metals have harmful health effects has been common knowledge for decades or longer. This is the case with mercury, which was recognized in the 19th century to cause neurological damage in workers who made felt hats—the origin of the expression “mad as a hatter” and the inspiration for the character the Mad Hatter in Lewis Carroll’s Alice in Wonderland. The devastating effects of the mercury discharged by a plastics factory into Japan’s Minamata Bay in the 1950s caused some 700 deaths and varying degrees of paralysis and brain damage in 9000 other people. The mercury accumulated in fish, which were the staple of the community’s diet. Another well-known episode of mercury poisoning occurred in Iraq in 1972, when the substance was used as a fungicide on seed grain. The contaminated wheat was turned into bread, which poisoned more than 6500 people, 459 of whom died.3(Ch.7)
In the United States, mercury enters the environment mainly by emissions from coal-burning power plants. The heavy metal falls to earth and becomes a hazard to humans mainly by getting into fish. Because the developing brain is most sensitive to the toxic effects of mercury, pregnant women and women who may become pregnant, as well as nursing mothers and young children, are advised to avoid eating fish species that have the highest average amounts of mercury in their flesh: tilefish, swordfish, king mackerel, and shark. Up to 12 ounces per week of other species of fish are considered safe. Mercury is regulated under both the Clean Air Act and the Safe Drinking Water Act.
People may be exposed to mercury when the liquid metal is spilled, releasing toxic vapors, for example, after a glass thermometer breaks. Mercury may also be found in equipment used in school science labs, and exposure may occur if the equipment breaks or is mishandled. The EPA recommends that mercury-containing products be removed from homes and schools. The sale of mercury-containing fever thermometers is banned in many states; safer alternatives are available. Cleanup of mercury spills requires great caution in order to prevent droplets of the metal from accumulating in small spaces and releasing vapors into the air. The EPA cautions against trying to clean up mercury with a vacuum cleaner or broom, or pouring it down a drain, because these methods are likely to put more of the toxic vapors into the air.4
Lead is another metal known to harm the brain and nervous system, especially those of children. It also damages red blood cells and kidneys. Lead is believed to be the single most important environmental threat to the health of American children, who may be exposed to it from a variety of sources. Over the past three decades, evidence has accumulated that even low levels of lead can slow a child’s development and can cause learning and behavior problems. The federal government recommends that all young children poor enough to be eligible for Medicaid be screened for lead in the blood, and some states have extended the mandate to children of all income levels. Permissible levels of lead have been steadily lowered from 60 micrograms per deciliter of blood in 1970 to 5 micrograms at present.5
Lead has been used—and has been causing lead poisoning—since the time of the Roman Empire, when it was a component of wine casks, cooking pots, and water pipes. In fact, the Latin word for lead is “plumbum,” the origin of the English word “plumbing.” Even today, a major source of lead exposure for millions of Americans is water contaminated with lead from lead pipes or from lead solder used with copper pipes. The use of lead in pipes was phased out in the 1980s, and newer homes use plastic plumbing.
Until the 1980s, lead was a significant air pollutant, emitted from the tailpipes of motor vehicles that burned leaded gasoline. As a result of the phasing out of leaded gas, lead levels in the air have dropped to negligible amounts. Lead was also a component of paint, both interior and exterior, until its use was banned in 1977. Children—especially those who live in old, substandard housing—are still significantly exposed when they chew on chips of old peeling paint or when they put dirty hands in their mouths if the dirt is contaminated with dust from deteriorating paint. Attempts to remove old lead-containing paint can sometimes be even more hazardous if it turns to airborne dust as it is sanded or sandblasted off a surface and is inhaled.
New alarms about lead surfaced in 2007, when the Consumer Product Safety Commission (CPSC) recalled millions of wooden toys that had been painted with lead paint, including the popular Thomas the Tank Engine. It turned out that the toys had been manufactured in China, which produces 70 percent to 80 percent of the toys sold in the United States.6 Consumer advocates note that toy safety is largely the responsibility of the companies that import them. The Commission suffered cuts during the George W. Bush administration and did not have the staff to monitor the safety of so many imports. Lead in toys is of special concern because young children often put them in their mouths. In 2008, Congress passed the Consumer Product Safety Improvement Act, which imposed regulations and testing requirements for toys and children’s furniture on manufacturers, importers, distributors, and retailers. The law limited the amount of lead allowed in paint or any similar surface coating on these products.7
Arsenic, “the king of poisons,” is well known as a common means of homicide through the centuries. It was not recognized as an important environmental toxin until the United Nations Children’s Fund inadvertently turned it into one in the 1970s in India and Bangladesh.8 Concerned about epidemics of cholera, dysentery, and other waterborne diseases, the organization led a campaign to drill millions of wells so that the population would no longer need to drink contaminated surface water. However, it soon became apparent that people began to develop symptoms such as abdominal pain, vomiting, diarrhea, pain and swelling in the hands and feet, and skin eruptions. In some cases, symptoms progressed to progressive nervous system deterioration and death. Children of poor nutritional status proved to be especially susceptible to these problems. The well water, while free of disease-causing bacteria, was found to contain very high concentrations of arsenic. With 80 percent of Bangladeshis affected, the World Health Organization has labeled this “the worst mass poisoning in history.”8(p.A386) Developing effective strategies for mitigating the effects of arsenic has been called one of the most important environmental health challenges of our time.
Studies have shown that, at somewhat lower concentrations, long-term exposure to arsenic in drinking water increases risk of diabetes and cancer. In the United States, regulations call for public water systems to contain no more than 10 micrograms per liter of arsenic, well below levels known to cause harm. However, people in some parts of the country who have private wells may be drinking water that contains 50 to 90 micrograms per liter of arsenic. The risks from chronic exposure to these amounts are not known.8
Asbestos is a fibrous mineral valuable for a variety of uses because of its strength and fire resistance. The hazards of asbestos were first recognized in an occupational setting: Inhalation of high concentrations of asbestos dust caused stiffening and scarring of the lungs of miners and other asbestos workers, a condition known as asbestosis, which can be disabling and eventually fatal. Regulations limiting exposure were instituted, but as workers began to live longer, many of them developed cancer. They were especially likely to get lung cancer or mesothelioma, a rare cancer of the lining of the chest or abdominal cavity that seems to be caused exclusively by inhalation of asbestos. As a result of a succession of lawsuits brought by injured workers and their families in the 1960s and 1970s, the Manville Corporation—the largest asbestos company in the United States—filed for bankruptcy in 1982.9 Once the dangers of asbestos were recognized, many uses of the material were banned, and standards for occupational exposure were tightened. However, asbestos can still be found in brake linings and a number of construction materials.3(Ch.7)
The general public is most likely to be exposed to asbestos fibers released into the air in the dust from crumbling walls and ceilings of old, deteriorating buildings. This is a special concern in schools, since all schools built or renovated between 1940 and 1973 were required to install asbestos insulation as a fire safety measure. Children’s exposure is of special concern because they would live for many years with the fibers lodged in their lungs, and the likelihood of developing cancer would increase with time. In 1986, the Asbestos Hazard Emergency Response Act was passed. It required all primary and secondary schools to be inspected and, if loose asbestos was found, to carry out plans for removing, enclosing, or encapsulating material. Unfortunately, the removal was often done improperly, causing more asbestos to be released into the air than if the material had been left intact. Other schools, unable to afford the expense of asbestos removal, ignored the rulings.3(Ch.7) There is no evidence thus far that exposure to asbestos has been a significant cancer risk to the general population.
However, the population of Libby, Montana, was clearly harmed by decades of exposure to asbestos. The vermiculite ore that had been mined in the Libby area since the 1920s was heavily contaminated with asbestos. A study by the National Institute of Occupational Safety and Health found that among 1675 Libby workers, 15 died of mesothelioma, a very rare disease, and the death rate from asbestosis was 165 times higher than expected. Death rates from asbestosis among residents of the area were approximately 40 times higher than the rest of Montana and 60 times higher than the rest of the United States.10
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