People of a certain age may remember Merthiolate and Mercurochrome in the household medicine chest.

Whenever someone skinned a knee or scraped an elbow, one of these topical antiseptics was often applied to prevent infection.

Mercurochrome was good for impressing children. It had a distinctive dark red color that stained skin, and it stung when it was put on the skin. Merthiolate had similar properties.

Both over-the-counter products contained mercury.

The active ingredient in Mercurochrome was merbromin, while Merthiolate contained thimerosal as its active ingredient. Thimerosal was also found in nasal sprays, eye wash, diaper rash treatment and vaginal spermicides.

Since virtually every household in America had a mercury-containing glass thermometer, there wasn’t much concern about this potentially toxic element.

A horrifying public health disaster in Japan in the mid-20th century brought mercury poisoning to the world’s attention.

A petrochemical company had polluted Minamata Bay with mercury. People who ate fish and shellfish from the bay accumulated large amounts of methylmercury in their bodies. Nine hundred died, and countless others were permanently disabled , according to The Lancet.

That was long ago and far away, but it did start to raise red flags. In 1980, the Food and Drug Administration began reviewing the safety and effectiveness of mercury-containing products. In 1997, Congress passed the Food and Drug Administration Modernization Act. It required the agency to investigate mercury in foods and drugs. Subsequently, in 1998, the FDA banned the use of thimerosal in over-the-counter products.

Congress also expressed concern about the use of mercury in vaccines administered to kids. In 2001, thimerosal was removed from all vaccines for young children. The only vaccines that continued to be preserved with thimerosal were multi-dose vials used for influenza immunization.

Meanwhile, the states began to recognize that mercury posed a hazard. Glass thermometers broke easily and the mercury that spilled out was difficult to collect.

Mercury, also known as quicksilver, is liquid at room temperature. People exposed to mercury by breathing, touching or consuming it could experience serious toxicity.

Long-term exposure can result in mercury poisoning. Because of these hazards, at least 13 states have forbidden the manufacture or sale of mercury thermometers.

In practical terms, mercury thermometers have disappeared.

There is no question that methylmercury is extremely toxic, which is why pregnant women are warned to avoid consuming large fish such as shark, king mackerel, tilefish, swordfish and albacore tuna.

Because these fish eat so many smaller fish, they tend to have high levels of methylmercury.

The controversy in 2025 centers on ethylmercury (thimerosal) rather than methylmercury. Scientists have been arguing about its safety for decades. According to the European Medicines Agency, other preservatives may be equally effective against microbes under some conditions. However, the trend is toward eliminating the use of multi-dose vaccine vials and the need for preservatives.

The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices met on June 25, 2025, and called for vaccines to be free of thimerosal going forward.

Critics of the committee’s decision worried that not having multi-dose vials available would mean fewer people would be immunized against the flu.

But only about 4% of the current flu vaccine supply contains thimerosal. Perhaps it’s time to eliminate all mercury from pharmaceuticals.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 300 W. 57th St., 41st Floor, New York, NY 10019, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”