These and other units of measure are defined in the Glossary of Environmental Health Terms available from the New York State Department of Health. A person's dose can be determined by multiplying the concentration of the chemical times the amount of the water, air, food or soil that a person takes in. If drinking water contains 1 milligram of lead per liter, then the person would take in a total of 2 milligrams of lead in a day. Long-term exposure is called chronic exposure. Either may cause health effects that are immediate or health effects that may not occur for some time.
Acute exposure is a short contact with a chemical.
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.