Researchers Discover Toxic Chemical in California Fog

Fog along the California coast contains elevated levels of the neurotoxin monomethyl mercury, according to a recent study.

The San Francisco Chronicle reports that the amount of monomethyl mercury in the fog — which equates to about 20 times more than the amount in rainfall — poses no immediate health concern, but that the chemical does build up amid repeated exposure.

The analysis also established a new way that the chemical can accumulate in the environment.

“Understanding the mechanism — a process that reaches into the ocean, pulls out a neurotoxin, then shuttles it ashore in fog — is very important,” Kenneth Coale of Moss Landing Marine Laboratories along Monterey Bay told the Chronicle.

Coale, UC-Santa Cruz professor Peter Weiss-Penzias and other researchers formed the FogNet project, which collected fog particles in mesh nets at stations along the coast in recent years.

Scientists said that ocean currents and particles from evaporated ocean spray combined to convert dimethyl mercury into monomethyl mercury, which then came ashore via fog.

Plants and animals in foggy areas contained up to 10 times more monomethyl mercury than their counterparts in other environments. Researchers also said that climate change could extend the fog's reach into California in coming decades.

The scientists said that policymakers should take steps to limit mercury emissions, which largely stem from coal-fired power plants and other fossil fuels.

The Obama administration implemented rules to curb mercury emissions from power plants in 2012. The Supreme Court rejected the rules over cost issues earlier this year, but an appeals court last month left the regulations in tact while the government addresses the high court's concerns.