May 4, 2023

New Toxicological Profile Published for Nitrophenols

A new final toxicological profile for nitrophenols is available from the Agency for Toxic Substances and Disease Registry. Nitrophenols, which include three chemical compounds, are manufactured and used in the production of dyes, rubber, photographic chemicals, medicines, pesticides, and fungicides, ATSDR explains. They are also formed in automobile exhaust—the main source of nitrophenol release—and can form from the breakdown of certain pesticides used for crop protection. According to the agency, individuals who live or work near roadways with heavy traffic may be exposed to higher levels of nitrophenols in outdoor air. Farmworkers or waste workers who use certain pesticides may also be more exposed to these chemical compounds than the general public.

ATSDR states that no studies have examined health effects among humans with confirmed exposure to nitrophenols but that the compound 4-nitrophenol has been shown to be a skin and eye irritant in animals. Results of studies in rats suggest that inhalation exposure to 4-nitrophenol “could reduce the blood’s ability to carry and deliver oxygen to tissues and organs,” the agency notes. Other research involving rats and mice indicates that ingestion of 4-nitrophenol may result in decreased body weight. The U.S. Department of Health and Human Services, EPA, and the International Agency for Research on Cancer have currently not classified the cancer causing risk of nitrophenols in humans.

New final toxicological profiles are also available for chlorodibenzofurans, which ATSDR describes as “a family of chemicals that contain one to eight chlorine atoms attached to the carbon atoms of the parent chemical, dibenzofuran,” and the chemical n-Nitrosodimethylamine, or NDMA, which the agency says is currently only made in small amounts for research purposes.

ATSDR toxicological profiles characterize the toxicology and adverse health effects information for hazardous substances. The peer-reviewed profiles identify and review the key literature describing substances’ toxicological properties. Information on substances’ potential for human exposure; chemical and physical properties; regulations and guidelines; and production, import, use, and disposal can also be found in ATSDR’s toxicological profiles. A full list of toxic substances with published profiles is available on the agency’s website.