California’s Office of Environmental Health Hazard Assessment (OEHHA) announced it has established a Proposition 65 Maximum Allowable Dose Level (MADL) for exposure to metham sodium of 290 micrograms per day by amending Section 25805(b) of Title 27 of the California Code of Regulations.
OEHHA reviewed the studies that provide information on the developmental toxicity of metham sodium that was identified by U.S. EPA in the materials that formed the basis for listing metham sodium as causing reproductive toxicity. These studies were reviewed as the possible basis for establishing a MADL for metham sodium. Additional relevant studies, conducted subsequently to those studies, were identified through literature searches, and OEHHA also reviewed these studies as the possible basis for the MADL for metham sodium. The most sensitive studies deemed to be of sufficient quality have been selected to provide a basis for the MADL.
The MADL for Metham Sodium was approved by the state’s Office of Administrative Law on July 25, 2018.
Metam sodium is an organosulfur compound used as a soil fumigant, pesticide, and herbicide. It is one of the most widely used pesticides in the United States.
Metam sodium is the sodium salt of methyl sodium dithiocarbamate.
Upon exposure to the environment, metam sodium decomposes to form methyl Isothiocyanate.
Metam sodium is a documented cause of reactive airways dysfunction syndrome.
In 1991 a tank car with 19,000 gallons of Metam sodium spilled into the Sacramento River above Lake Shasta.
This killed all fish in a 41-mile stretch of the river. 20 years later the rainbow trout population recovered.
Metham Sodium was listed as a carcinogen on November 6, 1998, via the Authoritative Bodies listing mechanism based on toxicity reports by the US EPA.
The chemical was also listed as causing developmental toxicity on May 5, 1998, based on a US EPA Authoritative Bodies listing.