Toxic Tuesdays

CHEJ highlights several toxic chemicals and the communities fighting to keep their citizens safe from harm.

Interpreting Health Risks

Community leaders are constantly asking government officials and scientists to explain the risks of being exposed to toxic chemicals. The answers they get are typically all over the place. Often people hear that you don’t have to worry, that the risks from living near a toxic contamination problem is no different than smoking cigarettes, eating a peanut butter sandwich, or living in an urban area. Government and industry further argue that it has never been proven that the health of the people at Love Canal was damaged by the chemicals leaking from the landfill, that the dangers of dioxin are overstated, and that people become “hysterical” just because they have been exposed to toxic chemicals.

No question people are upset. But they’re not upset because they can’t understand complicated risk assessments or detailed toxicity information. They are upset because government and industry trivialize their concerns, because they can’t get good information on the toxicity of chemicals, and no one will give them an honest answer about potential health effects caused by exposure to toxic chemicals.

There is no question that toxic chemicals can cause adverse health effects. What’s not so clear is how chemicals cause adverse health effects in people. Part of the reason for this is that for most chemicals, there is not enough information on what happens to people when they are exposed while eating contaminated food, drinking polluted water, or breathing toxic air. A classic 1984 National Academy of Sciences report found that we had good information on only 8% of over 65,000 chemicals in use. Not much has changed since then.

While most of the information on toxicity of chemicals comes from animal studies, the workers who manufacture toxic chemicals are the greatest source of information on the toxicity of chemicals. From their experience, we found that dusty air causes lung cancer, benzene causes leukemia, radioactive paint, bone cancer, vinyl chloride, liver cancer, and certain pesticides, muscle weakness and paralysis.

In the community, an association between health problems and exposure has been harder to “prove”, but still many examples exist, especially among children who are highly susceptible to toxic chemicals. At Love Canal, children who were born and raised next to the canal had higher rates of birth defects; in Tucson, AZ, children whose parents drank water contaminated with trichloroethylene (TCE) were born with 2-1/2 times more heart defects than normal; and in Santa Clara County, CA, state health researchers found an “unequivocal excess” of miscarriages and birth defects in a San Jose neighborhood where trichloroethane (TCA) and other toxic chemicals were found in the drinking water.

Despite these and other findings, scientists still find it extremely difficult to tell exactly what health effects will occur following exposure to toxic chemicals. There are a number of reasons for this. First, many factors determine what happens when a person is exposed to chemicals, including how an individual body responds to exposure (this varies widely from person to person), how long exposures occur, how many chemicals you’re exposed to and their toxicity. Without knowing these variables, it’s difficult to predict what will happen when a person is exposed (in most instances, most of these factors are unknown).

A second factor is that many symptoms or diseases are not specific to a particular chemical. In most instances, there can be many causes of the symptoms that people are having. And since few physicians have any experience with exposures to toxic chemicals, rarely do they look at chemicals as a possible explanation. For example, many physicians will diagnose a person who is fatigued, moody and without appetite as “depressed”, likely to have a problem at home or at work. Seldom is exposure to toxic chemicals considered, even if it’s raised by the patient.

Another problem is determining what the “normal” rate of illness or disease is in a community. Scientists simply can’t decide amongst themselves what is normal, in large part because of the many uncertainties we’ve already discussed.

As a result, interpretation of the risks posed by exposures to toxic chemicals is largely a matter of opinion, not fact. Government and industry may criticize people for being “hysterical” or emotional when trying to explain health risks. But without clear information and explanations, people are pretty much out in the cold. Scientists need to be more honest about what is known and what’s not known about low level exposures to mixtures of chemicals. Once people have this information, they may not be fully satisfied, but at least they have a good sense of what’s known and what’s not. Then people are in a better position to decide what action they need to take.

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