Cumulative Risk from Airborne Chemicals
Normally, people are exposed to many chemicals from many sources every day—both human-made and naturally occurring—in food, water, soil, and air. For example:
◦naturally occurring chemicals and food additives
◦emissions from cars, dry cleaners, and industrial sources
◦natural minerals such as arsenic and by-products from disinfection in drinking water
◦chemicals from soil that volatilize (become vapors)
◦emissions from vegetation and wildfires
Exposure to chemicals is associated with some level of risk of adverse effects on health (defined as damage to normal functions of the body, which can include such problems as irritation and lung disease, as well as cancer). The body can generally remove harmful chemicals, but sometimes it may not be able to get rid of a chemical before it can cause harm. As the amount of chemical a person is exposed to increases, so does the likelihood of harm. Exposure of a person to one chemical from multiple sources is called aggregate exposure. Exposure from multiple sources is called cumulative exposure.
Cumulative risk is the combined risk from exposures to multiple chemicals from multiple sources. Cumulative-risk assessment aims to evaluate adverse health effects from all chemicals from all possible sources to determine the overall risk to human health.

For more detailed information on risk assessment at the TCEQ, please contact the Toxicology Division, by phone—toll-free: 877-992-8370, local: 512-239-3900—or e-mail: tox@tceq.texas.gov.
E-mail us at tox@tceq.texas.gov. If you wish to reach a particular staff member, please put “Attn:” and the staffer’s name in the subject line.
Phone Numbers
Toll-Free: 1-877-992-8370
Local: 512/239-1795
Fax: 512/239-1794
Toxicology Division Director
Michael Honeycutt, Ph.D.
Toxicology Division Section Manager
Sabine Lange, Ph.D., DABT
Toxicologists
Stanley Aniagu, Ph.D.
Sainath Babu, PhD.
Angela Curry, M.S.
Cassandra Henry, PhD.
Janet Hamilton, Ph.D., DABT
Joseph Haney, M.S.
Allison Jenkins, M.P.H.
Jong-Song Lee, Ph.D.
Stony Lo, Ph.D.
Darrell McCant, M.P.H.
Jessica Myers, Ph.D.
Nnamdi Nnoli, Ph.D.
Tracie Phillips, Ph.D.