Key Concepts
Toxic Substances, Environmental Consequences and Human Health
Assessing Risk
Risks and Routes of Toxic Exposure
Some Toxicants in the Air
Some Toxins in the Water
Some Toxicants in Food
Some Toxins in Building Materials
Who Is at Risk
Head Start Facilities
Questions for Discussion/Reflection
SUSTAINING A HEALTHY ENVIRONMENT
KEY CONCEPTS
Preventing exposure to environmental hazards is a critical piece of the total picture of health protection, health services and health education in Head Start.
Many hazards exist in homes, schools and communities. These hazards affect the health of children and adults. Exposure to hazards comes from four main routes, and protection strategies can be planned for each route:
- air (indoor and outdoor)
- water
- food
- building materials and household products
Because of their behavior and their physical development, children are uniquely exposed to and affected by environmental pollutants.
A number of environmental concerns must be addressed to provide safe and healthy facilities for Head Start program staff and families.
Background Information
A. Toxic Substances, Environmental Consequences and Human Health
For most of the thousands of years of human history, the environment was a powerful, all-enveloping force. People had to adapt their behavior to climate, storms, pestilence, and other forces beyond their control. Many people lost their lives through injury or illness related to natural forces. But, in the past few hundred years, human beings have "tamed" nature in various ways. We have altered natural systems to give ourselves a comfortable, more predictable life. These alterations range from the development of the automobile and related vehicles to vaccines and antibiotics, pesticides and fertilizers for crops, and systems for air conditioning and heating our homes.
Until the 1950s and 1960s, these improvements were seen by most people as completely beneficial. People saw that science could improve their lives by offering convenience and comfort, protection from illness, and a wider variety of food at lower prices. But, during the second half of the 20th century, two things happened: First, the pace of development and release of unnatural substances into the environment increased dramatically; second, people began to notice and name toxicants that are harmful to human health and the health of other members of the ecosystem.
How have things changed? How fast? A few examples follow:
- At least 70,000 man-made chemical compounds have been invented and dispersed into the environment; 300 new substances are created each year.
- In 1993, an estimated 4.23 billion pounds of pesticides were used in the United States.
- The amount of lead "available" in our environment-meaning present in forms which can damage humans-is hundreds of times greater than that "available" in the 1950s.
- In 1960, 6.3 billion pounds of plastics were produced. By 1991, production had increased tenfold to 62.8 billion pounds. Of this total, 276 million pounds were used to make disposable diaper liners and 1.5 billion pounds were made into plastic trash bags.
Awareness of the toxins' harmful effects came slowly. Rachel Carson's Silent Spring (1962) woke up many people with its details of the effects of pesticides on wildlife. Health care providers began to tie various negative health effects in children to lead poisoning. Increases in asthma and other respiratory illnesses were correlated with air pollution. Acute poisonings from polluted water and pesticides drew attention to the toxicity of a variety of chemicals and raised questions about the chronic effects of these chemicals. When they were used over long periods of time, we began to see strains of antibiotic-resistant diseases, such as gonorrhea and tuberculosis. Agricultural pests and lice also developed resistance to the insecticides used to control them.
A Note About Terminology:
Three words are commonly used to describe harmful substances, which can be either naturally occurring or man-made: toxic, toxin, and toxicant.
- Toxic: Often used as a noun, toxic is more correctly used as an adjective - e.g. toxic air pollutants, toxic waste - describing something poisonous.
- Toxin: The term toxin is used by scientists in a limited way to describe the toxic protein-like product of a living organism, such as snake venom.
- Toxicant: The most inclusive term, a toxicant is any substance that produces toxic effects.
In this training guide, we use these terms interchangeably.
B. Assessing Risk
The sheer volume of potentially toxic products that surround us seems almost overwhelming. It is easy to see why many people decide to either (1) ignore the problem and hope it will go away or (2) become frantic in trying to eliminate all risks from their lives.
However, what we all really need to do is to learn to assess environmental risk, and take steps individually and collectively to minimize those risks. This module discusses protection from individual risk, then Module 3: Building Communities Which Consider the Seventh Generation explores the collective action that can have larger impact.
What is a risk? A risk is a chance that something harmful or unwanted will occur-depending on what a person does or is exposed to.
Some environmental risks are clear-cut. We know that breathing air contaminated with cigarette smoke is hazardous; several illnesses result from the exposure. We also know that certain levels of lead in the bloodstream can have damaging effects. The risk assessment, however, becomes much more complex when we consider the long-term effects of low-dose exposure to toxins.
An extra challenge in assessing risk from an environmental toxin is that no one is exposed to only one risk. Regulations and manufacturers' guidelines set limits on the exposure a person can receive without harm from a given substance, but they do not consider that people might be exposed to several different substances. These substances generally do not act independently, and can work together to multiply the toxic effect.
For someone to decide whether to avoid a certain environmental risk, he first needs information. With the information, a person can make a judgment about which risk is acceptable and which—for a variety of reasons—is unacceptable.
Scientists ask questions when faced with the possibility that a substance is harmful. Then they evaluate the information in the answers.
- How many studies were done to show that this is harmful? It is unwise to rely on one study or one incident of harm to determine that there is a general risk. The determination should be based on several studies done with good scientific methods.
- How strong is the association between the supposedly harmful substance and the harmful effect that we see? If a group of people exposed to a certain substance have a lot more cases of a disease than a similar group who are not exposed, then there is a strong association. If only a few more cases, the association is weak.
- Does increasing the "dose" increase the chance of harmful effects? If a child with asthma has little trouble breathing when the air is clear, but wheezes more as pollutant levels rise, that is a "dose response." It suggests that air pollution makes her asthma worse.
- Does this harmful effect make sense given what we know about human biology? For example, we wonder if a certain toxicant affects the offspring of workers who are exposed. Let's say that the workers, men and women, were all exposed at age twenty. They all have children ten years later. Some children have birth defects.
Did the toxicant cause these? Well, maybe yes for the women; probably not for the men. Why? Human biology. A toxicant that affected a group of women who were twenty years old might very well affect the children they conceive ten years later because women's egg cells are present in their bodies from their infancy. However, since men's sperm cells are not present from infancy, the men's exposure to the same toxicant at age twenty would be less likely to affect children they help to conceive later.
Once the information is in, it is time to make a choice. Do I change what I do, where I live, what I eat - so that I reduce my risk of a harmful effect from some substance? As with other health topics, the facts are only part of educating people about risks to their well-being. People might be more or less concerned with environmental risks depending on several factors.
- Is the risk voluntary or involuntary? Many people accept the risk to their families from the smoke of their own wood stove (voluntary), but are unwilling to accept the county planner's decision to put a highway nearby, which will increase auto exhaust (involuntary).
- Can I do anything to control my personal risk from this hazard? Someone might be aware that the public water supply is not safe, but block out the information because he cannot do anything about it. Or, he might respond to warnings of the risk and make some helpful changes, if he has information about something concrete that he can do to reduce risk to himself.
- Is this risk clear and obvious or is it something that might happen some time in the future? People usually pay more attention to risks that have immediate, observable effects. They either ignore or have vague worries about risks that accumulate over time.
- Where is this information about risk coming from and is the source trustworthy? People have learned that false information can come from all sides of an environmental question, and they have been confused by well-meaning scientists unable to explain risks in understandable terms. People are more likely to make changes that are recommended by a trusted person or organization.
In communicating about environmental risks, we must pay as much attention to people's concerns and perceptions of risk as we do to "the facts." Their concern, and our response to that concern, will be as important to their ultimate decision about what to do about a certain risk as will be the information we provide.
Head Start staff, because of their trusted position in their communities, can be valuable sources of information for families. People can easily be misled by sensational information and overreact to a sensationalized risk. Staff can assure that scientific information is clear and that bureaucrats and decision-makers respond to concerns. By considering the questions in this section, staff can take a critical look at a supposed risk, interpret information for families, and help them decide what to do.
C. Risks and Routes of Toxic Exposure
Thousands of substances can cause harm to human beings. To help staff to plan strategies to protect children, families, and themselves from these hazards, we have organized the substances into routes of exposure.
It is important to recognize that the following overview of risks only lists some broadly distributed toxins. Risk varies by region throughout the United States. For example, people working with pesticides or living near farms will be more exposed to those substances; those in the Northeast have more exposure to radon; those who live near heavy traffic will be more exposed to ozone and nitrogen dioxide.
With thousands of chemicals circulating in our environment, pinning exact cause and effect is tough. It took many years, many studies, and much argument to document that cigarette smoking does cause lung cancer. The effects of the toxins in the following tables are not unquestionably proven. The effects have been demonstrated in animal studies, or studies of humans, or both.
One thing to note: Scientists can measure many things, but are much less able to pinpoint the exact effect of a certain substance on health. For example, they may know that a nursing mother's milk contains a certain chemical, but they are unsure about that chemical's effect on her baby.
For the toxicants listed in the following tables, the intensity or severity of the response to the exposure will vary. Just as some people smoke cigarettes and do not get lung cancer, some people are exposed to environmental toxics and do not seem to be affected. Most of the following substances, however, are deadly if the exposure is great enough.
It should also be noted that illnesses or injuries caused by toxins - unless they are high-dose, acute exposures - can creep up on a person over time. Signs and symptoms might suggest another common illness but not respond to treatment. It is important to consider environmental damage as a possible cause for any illness.
Some Toxicants in Air:
What It Is: Tobacco Smoke
Source: cigarette smokers, includes a variety of pollutants
Effects: irritates lung passages; impairs oxygen transport; leads to respiratory illnesses, lung cancer
What It Is: Carbon monoxide
Source: from incomplete combustion of fuel: stoves and autos.
Effects: blocks the red blood cells' ability to carry oxygen
What It Is: Ozone
Source: formed from a combination of nitrogen and hydrocarbons (auto exhaust & industry) and sunlight
Effects: damages the respiratory tract; causes difficulty in breathing; asthma
What It Is: Particulates
Source: tiny particles of dust, soot, auto exhaust
Effects: impaired lung function; asthma; increased respiratory illness
What It Is: Radon
Source: a breakdown product of naturally occurring uranium; seeps into homes and schools
Effects: lung cancer
What It Is: Electric and magnetic fields (EMF)
Source: electric charges from any power line or electric appliance
Effects: biological changes in cells; possible association with cancer
What It Is: Ionizing radiation
Source: nuclear power plants, atomic weapons testing/use, nuclear waste storage sites
Effects: various cancers
What It Is: Ultraviolet radiation
Source: the sun
Effects: damages and wrinkles skin; causes skin cancer
Head Start has taken an important step in protecting children, staff, and families from air pollutants by banning smoking on the premises. The chart above highlights other pollutants.
The various types of radiation are included in the "air" category because they are all around us.
Some Toxins in Water:
What It Is: Pesticides
Source: appear in water supply as runoff of agricultural or landscaping use
Effects:
- acute: nervous system damage, skin irritation, gastrointestinal distress
- chronic: damage to nervous, immune, or reproductive systems; cancer
What It Is: Lead
Source: plumbing solder
Effects: damage to nervous and circulatory systems; learning disabilities and anemia
What It Is: Microorganisms (parasites, bacteria)
Source: sometimes found in well water, occasionally in public water systems with inadequate treatment
Effects: a variety of gastrointestinal illnesses
What It Is: Dioxin
Source: industrial processes; breakdown product of chlorinated compounds
Effects: various cancers
What It Is: PCBs (Polychlorinated biphenyls)
Source: electronic components
Effects: skin rash; liver cancer; central nervous system damage
We know that water is essential to life, and good nutritional practice encourages drinking many glasses of water each day. There is evidence that toxic chemicals can seep into water supplies (either surface or ground water) from a number of sources.
Lead, of all the heavy metals that contaminate water, has drawn the greatest amount of attention in recent years. Other metals that contaminate water include cadmium, aluminum, mercury, selenium and/or nitrates, depending on the area.
Some Toxicants in Food:
What It Is: Pesticides
Source: residues on food products, mostly fruits and vegetables
Effects:
- acute: nervous system damage, skin irritation, gastrointestinal distress
- chronic: damage to the immune, reproductive, or nervous systems, cancer
What It Is: Microorganisms (parasites, bacteria)
Source: improper food handling and storage
Effects: gastrointestinal illnesses (e.g., diarrhea and vomiting)
What It Is: PCBs (Polychlorinated biphenyls)
Source: electronic components: concentrated in the fatty tissues of fish
Effects: skin rash; behavioral disorders; liver cancer
One of Head Start's important goals is to provide nourishing food for children. Another is to build healthy eating habits among all program participants. We consider levels of sugar, salt, and fat in the food. Nutritionists advise us to eat several servings of fruits and vegetables each day.
Food safety is important to any food program. There are two general ways that food could be contaminated and unhealthy. Microorganisms can contaminate food at the farm or factory, or through unsafe food preparation practices at the Head Start center or home. With fresh fruits and vegetables, there might be residues of pesticides or other chemicals. In August 1996, the growing concern about contamination of fresh produce resulted in the passage of a new law, the Food Quality and Protection Act of 1996. This law changes some of the ways that pesticides have been regulated. For the first time, specific information about the effects of pesticides on infants and children is considered.
There is great regional variation in food growing practices and in eating practices. Some people eat more apples, others more meat. The greatest risk of PCB ingestion is faced by those whose diets are high in fish caught from lakes and bays that have been polluted by PCBs.
Some Toxins in Building Materials/Home Products:
What It Is: Formaldehyde
Source: pressed wood (much is used in mobile home construction), particle board, and carpets
Effects: irritates skin and respiratory system; headache; gastrointestinal distress
What It Is: Lead
Source: paint on walls, sills, etc.; pottery; cosmetics
Effects: nervous system damage; learning disabilities; anemia
What It Is: Asbestos
Source: building insulation
Effects: skin irritation; lung cancer
What It Is: Home cleaning/pesticide products
Source: cleaners; bug spray; chemicals for landscaping
Effects: skin irritation; childhood cancer; nervous system effects
What It Is: Organic solvents
Source: products used to dissolve grease and paint
Effects: cancer; skin irritation
Many products used in the home are very toxic.
In 1786, Benjamin Franklin wrote to a colleague and described the signs of lead poisoning he had observed among workmen in different countries. Two hundred years later, the problem of lead poisoning is still with us, mainly affecting children. Lead is a widespread substance, and exposure to this toxin can occur through many routes. Since the 1970s, lead exposure through air has dropped with the elimination of leaded gasoline and lead exposure through food has been reduced by removing lead from the canning process. Children still encounter lead through paint in older buildings or in the soil around those buildings. Because small children put everything in their mouths, they can easily ingest lead from toys, dirt, paint chips, or window sills.
Asbestos was used widely for many years in insulation. Workers have suffered from lung cancer as a result of their contact with this substance. Now, if asbestos is in place and intact, it does not pose a risk for users of the rooms where it is found. If it is disturbed - through flaking, peeling, or construction/renovation activities - it can be very harmful and must be removed by specially trained and experienced workers.
D. Who Is at Risk?
Environmental contaminants present a risk for everyone. Effects on adults range from acute episodes of poisoning to chronic exposures. Workers with toxic substances are the usual victims of acute exposures, from spills of pesticides or contact with cleaning supplies, for instance. An example of a chronic exposure is the experience of asbestos workers who developed lung cancer many years after their work with the substance. Another example is damage to reproductive systems in men and women who work over time with toxic chemicals. There is also some concern about reproductive damage from general exposure to chemicals in the day-to-day environment.
From conception through adolescence, children are physiologically different from and behave differently than adults. In general, the younger the child, the more potentially damaging is an effect from a toxic exposure.
Children's immature organ systems are especially sensitive to environmental hazards. Exposures might disrupt and cause permanent damage to developing nervous, immune, and respiratory systems of young children. Children's metabolic processes are quite different from adults': they absorb toxic materials more easily than adults through their skin and through their respiratory and gastrointestinal systems. They are also less able to detoxify, metabolize, and excrete certain toxins and so are more vulnerable to adverse health effects.
Children's behavior is also very different from adults'. Older children are outside more and engage in more active play. Infants and toddlers spend a great deal of time on the ground, lying or crawling, and putting all that they can reach into their mouths. They eat more fruits and vegetables than do adults and drink more water. Children are closer to ground level, and are exposed to toxins in the soil and in the air that is closer to the ground.
Children with disabilities are due special attention. A visually impaired child, for example, is more likely to work close to an art or craft project and breathe toxic fumes. Children with mental or emotional disabilities might not be able to follow safety precautions.
Tolerances for exposure to many toxic substances are established by manufacturers and government regulators. There are several reasons to be skeptical of tolerance limits and health protection. Health may not be protected, even when tolerance levels are not exceeded, because the limits:
- may have been set many years ago, with little information on acute effects;
- may not consider multiple exposures to a number of substances, which could interact with each other; and
- are usually not set for children, but for healthy, adult males. A "tolerated level" of a substance might expose an adult to a level that does not cause harm, but the child's exposure per pound of body weight is much higher. Children also have (hopefully) more years ahead of them than adults, so that the exposure might continue for a longer time.
Therefore, many child health experts are warning that children are not adequately protected by tolerances set for toxins in air, water, food, or building materials.
The experience with lead poisoning is an example of greater knowledge leading to establishing much lower tolerances, or action levels. Early in this century, people were not aware that low levels of lead in the bloodstream could cause damage to children; only acute lead poisoning with dramatic and damaging effects was known. As researchers documented effects on children at lower levels, the tolerance was changed. The Centers for Disease Control and Prevention (CDC) now considers a blood lead level above 10 mcg/dl unacceptable.
E. Head Start Facilities
Head Start programs are required to choose facilities that are conducive to learning, reflect the stages of development of each child, and are safe and healthy places for staff and family members.
Some important issues to consider in selecting facilities are:
- quality of the air (indoor and outdoor)
- drinking water supply
- landscaping and whether its care requires a lot of fertilizers and/or pesticides
- presence of toxic substances (e.g. lead, asbestos, hazardous waste) in soil, wall surfaces, or building materials
- overall energy usage of the facility - type and amount
- availability of wholesome food and clean, safe storage and preparation facilities
Consideration should be taken of the facility itself, the surrounding area, and the area through which children, families, and staff travel in the normal course of their Head Start day's activities.
Construction or renovation of facilities entails another set of questions that must be addressed, as construction could disturb or uncover toxins that otherwise would not be a problem. Examples are the need for specially trained workers to abate the problems raised by lead, asbestos, or serious soil contamination.
Note to Trainer/Coach:
This training guide takes an ecological approach to toxins, exploring those that cause damage to humans and others in the ecosystem. There are many other substances that are not inherently toxic, but can be dangerous if misused. There is also the issue of safe structures - design and shape - in the Head Start environment.
The latter two issues are explored in the Health guide Safety First: Prevention and Management of Childhood Injuries. You will also find information and activities related to the environment and communicable diseases in Preventing and Managing Communicable Diseases.
QUESTIONS FOR DISCUSSION/REFLECTION
- How do you feel about the changes in the ecosystem during your lifetime? Which changes have been good? Where have you seen harm?
- Think about risk. What changes have you made to reduce your risk of illness or injury? From any cause? From environmental hazards? What information did you receive? How did you make your judgment?
