SANTA MONICA—On Wednesday, August 5, Santa Monica beach was temporarily closed due to a mysterious substance, later identified as linoleic acid that washed up on the shore.

The white substance was first reported washing up on the shore at around 7:00 p.m. The Coast Guard initially thought that it might be a chemically treated substance from an ocean-faring boat. Due to safety concerns, lifeguards cleared the pier and portions of the beach. The evacuated area stretched from the 1700 block of Ocean Front Walk to Tower 15, and included the stretch of beach between lifeguard stations 15 and 17.

Several agencies were called to the scene to assist with the potentially hazardous material, including the Santa Monica Fire Department, the Santa Monica Police Department, and Los Angeles County lifeguards. At approximately 9:45 p.m., authorities determined that the material was not hazardous.

Linoleic acid is a fatty acid commonly found in nuts and fatty seeds like flax and hemp. It is sometimes used industrially in the manufacturing of quick-drying oils, such as the types found in oil paints and varnishes. When chilled, it forms the white substance found on the beach; at room temperature, it is a colorless liquid. Linoleic acid is not dangerous to humans.

After determining that the substance was safe to handle, authorities began the cleanup effort. They collected enough acid to fill about half of a 55-gallon drum.

The origin of the linoleic acid is still unclear. The beach and the pier will re-open as usual on Thursday, August 6.