Factsheet: Limiting Mercury Pollution

NRDC filed its first lawsuit against the Trump Environmental Protection Agency (EPA) for illegally rescinding a rule that would protect the public from 5 tons of mercury discharges every year. The Mercury Effluent Rule is simple, common sense, and supported by all major stakeholders, including the American Dental Association.

On December 15, 2016, the EPA issued for publication its final rule to address mercury discharged from dental offices into publicly owned wastewater treatment plants. The Mercury Effluent Rule is designed to require dental offices to remove mercury when it is still in amalgam form, which is much simpler and cheaper than requiring wastewater treatment facilities to remove it once it has been diluted. The rule will reduce the annual discharge of mercury by 5.1 tons to publicly owned wastewater treatment plants.

On Friday, January 20, 2017, shortly after the inauguration, the Trump White House issued a memo that directed federal agencies to “immediately withdraw” final rules sent to the Office of the Federal Register but not yet published in the Federal Register. In response, on Monday, EPA withdrew the Mercury Effluent Rule. EPA acted unlawfully. Repealing a final rule requires giving the public notice and an opportunity to comment, which EPA failed to do.

Mercury Pollution Is Dangerous to Human Health

Mercury is a dangerous neurotoxin that can disrupt brain function and harm the nervous system. It is especially harmful to pregnant women, their babies, and young children, even at tiny levels of exposure. Prenatal exposure to levels before considered safe are associated with lower IQ and adverse impacts on memory, language, and fine motor skills.

Mercury that ends up in our waterways is converted to methylmercury—a highly toxic form of mercury—and ingested by fish. When we eat these fish, we absorb methylmercury into our own bloodstream. EPA very conservatively estimates that more than 75,000 newborns each year may have increased risk of learning disabilities associated with prenatal exposure to methylmercury.

In the U.S., eating fish and shellfish is the main source of methylmercury exposure to humans. Mercury contamination of fish stocks is widespread in the United States.

Mercury Pollution from Dental Offices

Mercury pollution is a widespread national and global concern. It can come from many different kinds of sources—such as coal-fired power plants and industrial boilers, cement plants, the disposal of mercury-added products, and mining sites.

Mercury can also enter the environment from dental offices: excess amalgam from new cavity fillings or old amalgam fillings being replaced are washed down the drain, enter the publicly owned wastewater treatment plant, and are released into the environment. If the plant captures the mercury, it ends up in the sludge, which can be incinerated or landfilled and mercury released into the air. Wastewater treatment plants are not highly efficient at removing mercury; thus, mercury that isn’t captured is released into surface waters.

What Does the Mercury Effluent Rule Do?

The Mercury Effluent Rule requires dental offices to remove mercury by installing relatively low-cost and readily available equipment called “amalgam separators” and implementing very simple Best Management Practices (BMPs). One BMP prohibits the discharge of waste (“or scrap”). The other BMP prohibits the use of line cleaners that may lead to the dissolution of solid mercury when cleaning chair-side traps and vacuum lines.

The Mercury Effluent Rule Benefits Human Health and the Environment

The rule will reduce the annual discharge of mercury by 5.1 tons (as well as other metals in dental amalgam by 5.3 tons) to publicly owned wastewater treatment plants. While dental offices are not a major contributor of mercury to the environment generally, dental offices are the main source of mercury discharges to municipal wastewater treatment plants.

Reducing discharges of mercury to surface water means lower methylmercury concentrations in fish. These reductions mean economic benefits from improved human health and improved environmental conditions. Reducing mercury going into the publicly owned wastewater treatment plants also means less mercury air and soil emissions.

Many Dental Offices Are Already Complying

There are 130,000 dental offices in the U.S., and 88% of them are still using or removing dental amalgam fillings. About 40 percent of them have already installed the equipment requirement in the EPA rule. That’s because 12 states already have mandatory programs to reduce mercury discharges into wastewater treatment plants. Thus, only 48% of dental offices would have to install the equipment required by rule, which would cost about $800 per office.

The Mercury Effluent Rule Is Common Sense

All major stakeholders support this rule: the American Dental Association (“ADA”), environmental groups, the municipal wastewater treatment plant operators represented by their trade association, and the vendors who make the equipment that must be installed.

According to the ADA, the rule “represents a fair and reasonable approach to the management of dental amalgam waste” and “is preferable to a patchwork of rules and regulations across various states and localities.” The National Association of Clean Water Agencies (representing the municipal wastewater utilities) touted the rule as being “far less burdensome” than the proposed rule.

About the Authors

Mae Wu

Senior Attorney, Health program

Join Us