Proposition 65 and Lead in Crock Pots

Part III in a continuing series on lead in crock pots.

Proposition 65 defines the known universe …

The limits of what can be known about lead in crock pots in the U.S. are defined by California’s Proposition 65, the Safe Drinking Water and Toxic Enforcement Act of 1986. As you can tell from the omnibus name, this law is about far more than crock pots. But let’s follow their case, because it’s ultimately very instructive.

Prop 65 is among the crown jewels of California’s leadership in environmental health standards and testimony to the fact that the ballot initiative process hasn’t been all bad. It requires that warning labels be placed on products exceeding specified limits of a list of chemicals known to be harmful, limits typically 10 to 1,000 times lower than federal standards.

It doesn’t ban such products; it is merely a requirement that they be labeled. But by shedding light on key areas, this law has cleaned up many products and practices not only in California but in the rest of the nation.

Thanks to Prop 65, you can more or less reliably find out (within the limits of compliance and enforcement reliability) if your crock pot leaches more than 0.1 parts per million of lead, 10 times less than the FDA limit of 1.0 ppm, when subjected to standard testing.

But thanks also to that law, you can’t find out – other than by having it tested at a private lab – how much less than it leaches, because no company is going to make that information publicly available. And that goes for products you might want to compare with crock pots, such as the cast-iron enameled cookware you might be researching as a possible alternative.

So Prop 65 is a good thing. But below its required warning levels companies don’t have to quantify what’s there. So as long as products meet the standard, there’s no public information about which ones do a better job of doing so – that is, no information about no lead vs. small amounts of lead.

And you can’t tell by currently available over-the-counter tests, either; these are only sensitive enough to find levels exceeding FDA standards, 10 times the Prop 65 amount.

Most crock pots pass the test, but …

The good news is most major brands of crock pots pass the test, at least according to my informal survey. So do most major brands of cast iron cookware, enameled and bare. Don’t take my word for it, though. Before buying any cookware, check the company website or contact customer service to verify that it is not required to carry a Prop 65 label in the state of California.

You can also check for Prop 65 labels on Amazon. Look under “Product Details” for any given product. If that product carries a Prop 65 label, there should be a line there that says “California residents: click here for Proposition 65 warning.” I’d still confirm with the company either way. The labeling can be vague, and this is your chance to ask the company for details.

The bad news is that, as I explained in the previous post, medical research is increasingly suggesting that amounts of lead below the Prop 65 limit can be measurably harmful, particularly for children and developing fetuses.

So how much lead are we talking about here?

If your crock pot actually leaches the maximum allowable Prop 65 warning-free level of 0.1 ppm, that amounts to 100 micrograms per liter, or roughly 25 micrograms per cup.

That’s determined by a standard test known as ASTM-738, which involves subjecting the pot to 24 hours of a 4 percent acetic acid solution at 80 degrees Fahrenheit and analyzing the solution with high-tech lab instruments. Don’t try this at home unless your atomic spectroscopy absorption equipment is fully up-to-date. A reputable lab I checked with quoted me a price of $350 to have it done.

This leaching level may possibly be acceptable for adults, who absorb a far smaller proportion than children (8-15 percent vs. 50 percent) and excrete a far greater proportion (up to 99 percent vs. only 32 percent), but by the FDA’s own standards, even those developed prior to recent findings, it is unsafe for children consuming more than small amounts.

Using EPA estimates of the effects of exposure to given quantities of lead, the FDA has developed the PTTIL – Provisional Tolerable Total Intake Levels (FDA, 1993):

  • Children, ages 0-6 years: 6 micrograms a day
  • Children, over 7 years: 15 micrograms a day
  • Pregnant women: 25 micrograms a day
  • Adults: 75 micrograms a day

There are so many variables affecting the leaching, absorption and excretion of lead that it would be unwise to take these figures too literally. But they do provide enough of an idea to suggest extreme caution for children, though there may be a reasonable margin of safety for non-pregnant adults.

Why bother counting micrograms when you already know that no amount is acceptable? Well, because lead is so ubiquitous in the environment that most people are going to have to tolerate some.

Just because your crock pot can leach that amount doesn’t mean it does. But it does mean you can’t know whether it does or not without testing. And it means the best standard we have is not good enough for infants, children and pregnant women.


California Office of Environmental Health Hazard Assessment,

Cheng, John, FDA. “Elemental Analysis Manual: Section 4.6: Inductively Coupled Plasma-Atomic Emission Spectrometric Determination of Cadmium and Lead Extracted from Ceramic Foodware,” August 2010,

“Draft Lead Report,” California Department of Toxic Substances Control,  Hazardous Waste Management Program Regulatory and Program Development Division, August 2004, (note; contains misprint of 35 micrograms for pregnant women),

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