M/V WAARDRECHT; San Francisco, California

San Francisco, California | 1989-Feb-04

Initial Notification: NOAA /OMA was notified of the incident at approximately 1430 on February 4, 1989 by the U.S. Coast Guard Marine Safety Office, San Francisco, and requested to advise on the toxicity of the products involved and safety considerations, and to recommend a strategy to mitigate the impacts of the release. Dimethoate is a sulfur-containing compound with a mercaptin-like odor. Its high molecular weight and low vapor pressure makes it quite stable in solid form at ambient temperatures, and its odor is noticeable even in extremely low concentrations. NOAA hypothesized that some vapor from the solid dimethoate may have leaked into the closed container during shipment, and that it was this vapor that was detected while the vessel was en route to San Francisco. The concentration in the atmosphere within the container was probably never at a toxic level even though it would have been uncomfortable to breathe. Once the container was opened and exposed to circulating air, the detectable odor would dissipate rapidly. NOAA recommended that personnel involved in the inspection of the shipping container be suited in Level B protection as a conservative measure as dimethoate does not present a significant inhalation hazard when shipped in solid form. The primary concern with this product was to avoid inhalation or ingestion of airborne dust from a potentially damaged shipping container and to restrict dermal contact to minimize any chance of skin absorption. A visual inspection of the container by the Coast Guard Marine Safety Office found no evidence of damage to the container or spillage of dimethoate. Accordingly, the container was left aboard the vessel for continuation to the WAARDRECHT's destination in Mexico. The case was closed after the container was inspected and found to be undamaged. USCG district 11.