New mercury source targeted

Group reports 60 percent of neurotoxin in Bay Area wastewater is from dentists

By Beth Winegarner

Staff Writer

As mercury levels rise in Bay Area water systems, officials are targeting one of the neurotoxin’s primary sources: dentists.

As much as 60 percent of the mercury in the region’s wastewater comes from dental offices, according to studies from the Bay Area Pollution Prevention Group. However, wastewater treatment plants aren’t designed to remove heavy metals such as mercury from the water. By 2010, mercury discharges at the South Bayside System Authority treatment plant could exceed allowable levels, according to a recent article in the authority’s newsletter.

In San Francisco, Palo Alto and the East Bay, laws requiring dentists to stop flushing amalgams have reduced mercury levels significantly, according to Karin North, member of the Bay Area Pollution Prevention group.

“We saw a 94 percent reduction in the average mercury concentration coming out of [dental offices] and a 64 percent reduction once it reached the sewer lateral, where you have multiple businesses feeding into it,” North said.

Now, roughly 1,500 Bay Area dental offices no longer dump mercury-laden materials, according to Teresa Pischay, policy analyst with the California Dental Association. In unregulated parts of the Bay Area, including San Mateo County, wastewater officials and the CDA are urging dentists to divert those materials voluntarily.

The elemental mercury contained in dental fillings is safe, but once it enters local waters — particularly the shallow waters in parts of the San Francisco Bay — it becomes methylated mercury, which can contribute to symptoms of mercury poisoning, including birth defects and brain damage, according to North.

While many dentists want to reduce the amount of mercury they’re flushing into local sewer systems, setting up the technology for proper disposal can be costly, according to Pichay. A unit that collects amalgam waste at the dentist’s chair can cost $800 to $900, plus $400 a year in maintenance costs.

“We are members of the community at large,” Pischay said. “[Diverting mercury] naturally falls into our responsibility as citizens.”

bwinegarner@examiner.com

Bay Area NewsLocal

If you find our journalism valuable and relevant, please consider joining our Examiner membership program.
Find out more at www.sfexaminer.com/join/

Just Posted

Health care workers in the intensive care unit at Providence Saint John’s Health Center in Santa Monica, with Alejandro Balderas, a 44-year-old patient who later died. Even in California, a state with a coronavirus vaccination rate well above average, the number of people hospitalized with COVID-19 has nearly doubled in the past two weeks, according to a New York Times database. (Isadora Kosofsky/The New York Times)
Why COVID took off in California, again

‘The good news is: The vaccines are working’

Lake Oroville stood at 33 percent full and 40 percent of historical average when this photograph was taken on Tuesday, June 29, 2021. (Brian van der Brug / Los Angeles Times via Tribune News Service)
A kayaker on the water at Lake Oroville, which stands at 33 percent full and 40 percent of historical average when this photograph was taken on Tuesday, June 29, 2021 in Oroville, Calif. (Brian van der Brug / Los Angeles Times via Tribune News Service)
Facing ‘dire water shortages,’ California bans Delta pumping

By Rachel Becker CalMatters In an aggressive move to address “immediate and… Continue reading

Students practice identifying species in the school garden at Verde Elementary in Richmond during summer camp. (Photo courtesy of Verde Elementary)
Reading, writing and bike riding: How schools spent summer helping students recover from pandemic

By Sydney Johnson EdSource Bicycles typically aren’t allowed on the blacktop at… Continue reading

The San Francisco Public Utilities Commission launched a pilot program that offers up to 90 percent discounts on water and sewer bills for eligible customers. (Andri Tambunan/Special to ProPublica)
How does 90% off your water bill sound? Here’s who qualifies

The San Francisco Public Utilities Commission announced this week it is launching… Continue reading

Most Read