Scientists Investigate Toxic Exposure

NCEH and ATSDR participate in two week-long health observances during April: National Public Health Week (April 7-13) and National Environmental Education Week (April 13-19). Both NCEH and ATSDR work to protect people from exposure to environmental public health hazards. During the next two weeks, the blog will feature a series of six posts explaining exposure pathways or the ways in which people can come into contact with toxic substances.

Residents of Lisbon, Ohio, smelled the “rotten egg” odor of hydrogen sulfide coming from a nearby landfill. People in El Dorado County, California, inhaled naturally occurring asbestos when they drove on dirt roads. Members of these communities were exposed to toxic substances during everyday activities right where they lived, worked, and played.

The prospect of toxic exposure is alarming to anyone. But Agency for Toxic Substances and Disease Registry (ATSDR) scientists can investigate whether the amounts of exposure in a particular area can harm the people who live or work there. And in Lisbon, OH, and El Dorado County, CA, investigators found that the toxic exposures could indeed be harmful to health and recommended ways to reduce or eliminate exposure.

Common toxic substances can harm people

Categories of common contaminants that can harm people include the following:

• Fine particles in the air
• Heavy metals, such as arsenic, cadmium, lead, and mercury
• Chemicals such as benzene and polychlorinated biphenyls (PCBs), and chemicals in pesticides and herbicides
• Radiation and radioactive materials, including ultra-violet radiation

You are in contact with toxic substances

We come into frequent contact with chemicals in our homes, schools, workplaces and communities. Even products that we use daily, such as household cleaners, prescription and over-the-counter drugs, gasoline, alcohol, pesticides, fuel oil, and cosmetics, can contain toxic contaminants. In fact, any chemical can be toxic or harmful under certain conditions.

Anytime we are outdoors, we breathe in carbon monoxide and other air pollutants. Heavy metals, used or created by industry, can be released into the air or food chain. And too much time in the sun overexposes us to ultraviolet radiation.

Toxic substances can be released into the environment naturally or through leaks, spills, or man-made disasters. The place where a contaminant is released is called a source. The chemical, metal, gas, radiation, or other environmental toxin can travel from the source to you in the air, water, or soil or in food or beverages you consume.

People respond to these substances in different ways. Some people may be exposed and never be harmed, while others may be more sensitive and get sick. But to make you sick, a certain amount of a harmful substance must enter your body, whether you breathe it, swallow it, or touch it.

The human body has a good defense system, so it tries to get rid of harmful substances or change them into a less harmful form. But it can’t get rid of some of them. These are stored in the body and may remain harmful.

Many factors play a part in whether you get sick from contact with toxic substances, including

• what you are exposed to,
• how much you contact,
• how long the contact lasts,
• how often you are exposed, and
• how it enters your body.

Ever heard of an exposure pathway?

An exposure pathway is the route a substance takes from its source (where it began) to its end point (where it ends), and the ways people can come into contact with it (or be exposed to it). To determine toxic exposure, scientists must find the complete pathway a substance takes from its source to get into a human body.

Stay tuned for future blog posts that describe exposure pathways investigated by ATSDR scientists.