What about other benchmarks used by experts? There are no federal limits on the amount of lead that dietary supplements may contain. But the FDA does publish something it calls an “interim reference level”—a guideline for reducing the potential adverse effects of dietary lead exposure—which is 8.8 micrograms per day for women of childbearing age, and the agency told CR that the same level should be applied to all adults. This number is obviously higher than CR’s level of concern. But, crucially, the FDA’s interim reference level refers to total exposure from everything one eats and drinks in a day, not merely one source.
That’s important because the average American adult is exposed to up to 5.3 micrograms of lead per day through their diet, according to a 2019 analysis by FDA scientists. To put that into perspective, CR’s tests found that the two powders with the highest lead levels contained 7.7 micrograms and 6.3 micrograms in a single serving.
In other words, our testing suggests that when combined with the typical exposure through diet, someone taking one serving of these supplements would likely exceed the FDA’s interim reference level for dietary lead.
Lead standards for food and drink are another worthwhile point of comparison—to the extent that they exist. The Environmental Protection Agency does not regulate lead levels in food but has set an “action level” (a threshold that, if exceeded, triggers corrective action) of 10 parts per billion for lead in tap water. Authorities in the European Union and the United Kingdom use the same standard. The FDA has set an allowable level of 5 ppb for lead in bottled water and has proposed action levels for lead in juice of 10 to 20 ppb, depending on the type.
It’s important to understand that parts per billion is a measure of concentration and different from the micrograms-per-serving or micrograms-per-day figures CR uses for our level of concern. For comparison, seven of the protein supplements we tested had lead concentrations above 20 ppb, and three products had concentrations ranging from 60 to 70 ppb.
One notable regulatory outlier is the European Union, which has set the maximum amount of lead permitted in food supplements at 3,000 ppb, a level that CR’s own food safety experts and every independent doctor and expert we have contacted say is far too high. Established in 2008, that standard is over seven times greater than the average lead limit set by the EU for all other foods.
When we asked him about that standard, Pieter Cohen, MD, an associate professor of medicine at Harvard Medical School who has studied the safety of supplements for nearly two decades, initially thought the figure was an error. It “makes no sense,” Cohen said in an email to CR. “That’s a crazy limit.”
Rose Goldman, an associate professor of medicine and physician at Cambridge Health Alliance who studies lead exposure, said the EU limit was “more than an order of magnitude different” than other dietary lead standards. It’s unclear exactly why that is the case. Unlike many of the limits for heavy metals in food established by European authorities, the maximum level of lead permitted in food supplements hasn’t been updated in 17 years, despite sweeping changes in how scientists and regulators view lead exposure.