curing pelts to make felt hats, as well as other related furrier activities, were known to frequently suffer symptoms including mental instability, irritability, and tremors from exposure to mercury.75 The common thread behind the phrase “mad as a hatter” was the workplace use of mercury nitrate, which left many sickened, debilitated, or simply off kilter. Miners, gilders, and mirror makers in the Renaissance era and Middle Ages were known to suffer similar ailments as well, though it would not be attributed to mercury for centuries to come.76
Mercury commonly found in consumer goods
There’s a common, but potentially deadly, misconception that mercury has been banned from everyday products. In reality, the relatively rare earth mineral is widely used in the production of many consumer goods. In addition to its use in thermometer bulbs, mercury is also used in batteries, pesticides, and now in large quantities as an element of energy-saving CFL fluorescent light bulbs.
We face exposure through broken thermometers or light bulbs, both of which can emit vaporous mercury that’s quickly inhaled. That’s why instructions for cleaning up a mercury-containing CFL light bulb include an extensive list of steps to ensure basic safety, despite CFL’s touted reputation as “green” technology. A health study found that if a single CFL bulb breaks, mercury gas concentrations released can reach 800 µg/m3, more than eight times the Occupational Safety and Health Administration (OSHA) limit of 100 µg/m3 for adults in an eight-hour period.77 A research team also found that because an electrical current is charging the mercury vapor contained in all CFLs, and the curly shape of the bulb can make it more prone to tiny cracks in the phosphor coating that would otherwise protect people from those rays, the bulbs were giving off cell-damaging UV radiation.78 They recommended keeping one’s distance from these bulbs and encasing them in an extra glass structure just to be safe.
Mercury is even used in vaccines given to children. On October 9, 2015, California Health and Human Services Agency Secretary Diana S. Dooley issued a directive that suspended the ban on mercury in vaccines given to children, allowing those children to be injected with a mercury-containing vaccine preservative known as thimerosal. “I am granting a temporary exemption from California Health and Safety Code Section 124172 for seasonal influenza vaccine with trace levels of thimerosal to be administered to children younger than three years from October 9, 2015, through December 31, 2015, because the current supply of thimerosal-free vaccine for young children is inadequate,” wrote Dooley. In doing so, she demonstrated that even when governments recognize the threat of mercury toxicity to children, they will nevertheless allow mercury to be injected into children whenever supply conditions demand it.79,80
Flu shots, by the way, typically contain over 50,000 ppb of mercury—about 25,000 times the concentration limit of mercury allowed by the EPA in drinking water.
Coal-burning power plants
The argument made by many CFL proponents for CFL’s viability as an environmentally friendly technology despite its dangerous mercury content is that the energy it saves results in a net reduction of mercury emissions from coal-fired power plants. Such power plants eject thousands of pounds of mercury into the air every year, where it eventually settles to the ground, contaminating soil, water, and products for human consumption. According to the National Resources Defense Council, 33 tons of mercury pollution are emitted from power plants each year just in the United States alone.81
Limitations on these mercury emissions have only recently been put into place. In an attempt to curb such emissions, the EPA announced the Mercury and Air Toxics Standards (MATS) for power plants in December 2011, limiting the amounts of mercury and other hazards such as arsenic that power plants are legally allowed to emit.82 However, the rule still allows for 1.2 pounds of mercury per trillion BTUs of energy produced, and because even tiny levels of mercury accumulate in the environment, the cycle of pollution will undoubtedly continue.
Wildfires and mercury pollution
Wildfires are another significant cause of mercury pollution. A 2007 Global Biogeochemical Cycles journal article noted that mercury in the atmosphere accumulates on foliage, and when it dies or decomposes, that mercury then enters the soil where it is taken up by roots and incorporated into tree leaves and structures. When a forest fire sweeps the area, mercury is emitted and carried by the rising heat and smoke into the atmosphere. The authors concluded that forest fires comprise a fourth of all mercury emissions in the United States.83
Mercury emitted via waste disposal
Mercury is also burnt or disposed of throughout industry, creating a pattern of contamination that has yet to be reined in. Everything from hospitals to dentists’ offices, veterinary clinics, laboratories, septic haulers, residential neighborhood waste, batteries, printing, painting, pottery, scrap metal, and industrial laundry contribute to the mercury waste burden. Unburned quantities of waste materials are often dumped back into croplands and waterways via sludge-based fertilizers. Either way, these mercurial compounds reemerge in the environment and continue to pose health risks.84
Mercury in pesticide use and residual effects in croplands
Although the majority of agricultural inorganic mercury uses have been banned or discontinued in most countries throughout the world, mercuric chloride, an inorganic mercury-chlorine compound, is still allowed for use in some pesticides in the United States and other countries—while the residue from decades past still impacts background metal exposure.85 Populations that eat grains sprayed with those pesticides (or meat from animals that ingest those grains) also accumulate toxic mercury.
Production, use, and emission figures for this compound are unknown, but it’s estimated to be in the hundreds of metric tons in the United States alone.86 Avoiding or restricting imports cultivated with the use of this harmful pesticide from places like China, where regulations are lax or difficult to enforce, may prove difficult or impractical. Thus, banned formulations still appear in foods consumed by millions of people.
For example, my own research into certified organic vegan protein products made predominantly from rice protein grown and processed in China found mercury concentrations as high as .036 ppm.87 Given that some consumers of such products eat over 100 grams of these proteins each day, their mercury intake from this one product can exceed 3.6 micrograms. It’s also important to note that nearly all of these rice protein products are certified USDA organic, which most consumers assume means “free of toxic substances.” Yet, as I discussed previously, USDA organic standards have no limits whatsoever on mercury or any other heavy metals.
Mercuric chloride has also made headlines for its negative effects when found in industrial waste. Following complaints of a strong chemical smell making villagers ill, news outlet RIA Novosti reported that 200 tons of a banned mercury pesticide was discovered dumped in a Russian village in 2011.88 Just as with all heavy metals, once mercury is in the environment, it is exceedingly difficult to remove.
The EPA has listed inorganic mercury as a Class C “possible human carcinogen,” as the agency’s own Office of Research and Development acknowledges it is a developmental toxicant that can cause gastrointestinal erosion and kidney damage in addition to DNA damage and cancer in lab animals.89
Mercury in dental fillings
Elemental mercury is still used in amalgam dental fillings, which contain, on average, 50 percent mercury. The FDA issued a final rule in 2009 that reclassified mercury from Class I (least risk) to Class II (more risk) and officially classified encapsulated dental amalgam—a mixture of silver, tin, copper, elemental mercury, and a powdered alloy—as a Class II restorative medical device.90
Although the American Dental Association
