No risk of exposure to mercury in Clorox(R) bleach

Does Clorox® bleach contain harmful mercury? Or am I contributing to mercury pollution of our land and oceans by using Clorox® bleach? A Q&A with Jim McCabe, senior environmental scientist at Clorox.

Jim McCabe has worked at Clorox for more than 25 years. For the past 15 years, he has headed its environmental group, where he is responsible for the environmental safety and regulatory compliance of all Clorox products. The group also develops Clorox's corporate environmental policy and procedures and guides development of, among other things, Clorox's new GreenWorksTM line of sustainable cleaning products.

McCabe, who has a Master's degree in environmental management, also personally has conducted and published research on the environmental fate and safety of bleach and its byproducts.

Q: If you search "Clorox mercury" in Google, you get 197,000 results. So it sounds like there is definitely a connection between mercury and Clorox® bleach.

McCabe: When we did our last major round of testing in 2001 that included all seven of our U.S. facilities, we found no detectable level of mercury in our final bleach product (the detection limit is less than 0.2 parts per billion). To put that into perspective, federal rules allow drinking water to contain 2 parts per billion of mercury, or at least ten times more than the detection limit. Moreover, federal rules consider mercury hazardous waste at 200 parts per billion. In other words, by not finding any mercury at its detection limit, our bleach is at least a thousand times under the level of being considered a hazardous waste due to mercury.)

Q: So what is the connection between bleach and mercury, then?

McCabe: Historically, back when Clorox was started in Oakland in 1913, we used a mercury cell process to manufacture bleach in our own factory.

Basically, we took regular salt water and passed an electrical current through it, using mercury as one of the electrodes. That produced the two main raw materials that make up bleach - chlorine gas and caustic soda, a colorless, odorless liquid better known as sodium hydroxide. Those two materials were then mixed to create sodium hypochlorite solution, aka bleach.

The process is still basically the same, except for one key difference: We don't use mercury in our plants anymore. Clorox started moving away from mercury as early as 1936, when we began buying chlorine and caustic soda manufactured using an alternative method called the diaphragm cell process to manufacture chlorine and caustic soda.

However, there are certain limitations to the quality of the caustic soda that can be produced by diaphragm cells. For purity, we continued to buy chlorine and caustic from outside suppliers offering mercury cell caustic soda.

So up until the mid-1990s, we still bought chlorine, caustic soda, or concentrated bleach that originated from factories using the mercury cell process. In response to public health concerns, we developed a task force to look into this issue. We made a decision to eliminate the use of bleach or caustic soda manufactured by mercury cell plants. By the late 1990s, we had stopped using bleach or materials from mercury cell plants except at one of our facilities in Aberdeen, Md.

Q: Why did Clorox continue there?

McCabe: Due to local concerns, we agreed not to transport chlorine to our Aberdeen plant. Instead we purchased concentrated bleach to formulate our bleach. The only manufacturer close enough to supply high-strength bleach still used the mercury-cell process. That continued until 2001, when, with the approval of the local community, we switched to manufacturing bleach using chlorine and caustic soda, the same way all our other U.S. plants do. We buy that caustic soda from diaphragm cell plants.

Q: So does that mean Clorox no longer does any business in the U.S. with outside plants that still use mercury technology?

McCabe: We do on rare occasions still buy high-strength bleach manufactured with chlorine produced through a mercury cell process. However, mercury is not present in chlorine. Mercury is only present in caustic soda that is produced by the mercury cell method and we no longer purchase such caustic soda.

Ultimately, though, we do want to move entirely away from buying bleach made with mercury cell chlorine, too. We hope to do this soon. But the bottom line is if any trace amount of mercury is in our bleach, it'd be coming from the water, the same drinking water you and I drink.

Q: So am I at any risk from mercury exposure from using Clorox® bleach, or of polluting the water system with it?

McCabe: Not at all.

Q: What about this 2007 report by the non-profit group, Oceana, which claims (p. 46) Clorox® bleach still contains a high percentage of mercury?

McCabe: First off, if you look at Oceana's footnote (p.61), you'll see this wasn't based on their own research, but on information published by Boston University and the Boston University Medical Center. The information is outdated and inaccurate and we’ve taken measures to correct it. We provided BU and BU Medical Center copies of our test results and the medical center conducted its own tests confirming mercury was below its detectable limit of 1 part per billion. As a result, both BU and the BU Medical Center updated their Web sites to take out any reference to Clorox, though they unfortunately haven't corrected some of the related PDFs.

Q: What about Clorox's own facilities? Is any mercury discharged from them?

McCabe: We haven't had any citations or penalties from wastewater treatment facilities related to any mercury releases since we stopped using mercury cell caustic. We do not use mercury in our production processes and have taken measures to ensure that our raw materials are not contaminated with mercury.

Q: How about retired Clorox facilities that formerly used mercury? What is the status of cleanup efforts there?

McCabe: We conducted a remediation of our original Oakland manufacturing location. We identified an area where the soil under the building was contaminated by mercury and we removed the contamination. A little bit of mercury remains in shallow groundwater below the site, but we are monitoring the groundwater to make sure it is not leaving the site.

Q: So there is no threat from mercury based on the production of Clorox® bleach?

McCabe: No there isn’t.

Bleach is mostly water. So if any mercury is in our bleach it is likely coming from the water, the same water you and I drink.