It may last a few seconds or a few hours. For example, it might take a few minutes to clean windows with ammonia, use nail polish remover or spray a can of paint. The fumes someone might inhale during these activities are examples of acute exposures. If a chemical is used every day on the job, the exposure would be chronic. Over time, some chemicals, such as PCBs and lead, can build up in the body and cause long-term health effects.
Chronic exposures can also occur at home.
Some chemicals in household furniture, carpeting or cleaners can be sources of chronic exposure. Unless preventive measures are taken, people may be exposed for a long time to chemicals from their drinking water or indoor air. All people are not equally sensitive to chemicals, and are not affected by them in the same way. There are many reasons for this. People's bodies vary in their ability to break down or eliminate certain chemicals due to genetic differences.