This warning is legally required by the state of California for dietary supplements and many other products sold in that state which expose you to levels of one or more chemicals that may cause cancer or reproductive harm. The list of chemicals which can trigger a warning
includes hundreds of compounds but, unfortunately, the California law (known as Prop 65 or the Safe Drinking Water and Toxic Enforcement Act of 1986) does not require businesses to say exactly which compound is the reason for the warning.
California's limits are strict and, in many cases, go beyond any federal limit — particularly as the federal government has not established limits on contaminants in supplements, leaving that decision up to each manufacturer. ConsumerLab.com generally applies the Prop 65 limits when testing for contaminants in supplements. In ConsumerLab.com's experience testing thousands of supplements, it has identified many which exceed the California limit for lead, a heavy metal, which can occur in plant-based ingredients, such as herbs, as well as in minerals. Often these ingredients are not the primary ingredient in a product, but are part of a blend or proprietary formula added to enhance the product or distinguish it in the marketplace.
ConsumerLab.com has typically found that products which exceed the limits for lead contamination pose a greater risk to children and to women who are pregnant or nursing than to other healthy adults but, nevertheless, they represent easily avoidable sources of these toxic compounds. ConsumerLab.com has also found that manufacturers are often not aware that their product exceeds a Prop 65 limit and do not include a warning on the label, even when the product is sold in California.
Although California is the only state requiring this labeled warning, companies that sell products nationally sometimes include the label on products sold even outside of California.
In an effort to protect themselves from potential lawsuits in California for not displaying a required warning, some companies may affix the Prop 65 warning labels to products -- as well as to website pages about products -- regardless of whether or not the specific products exceed Prop 65 limits.
If you see a warning label of this type, you may want to check ConsumerLab.com's website
to see if there is information about the product. You may also want to contact the manufacturer or distributor to learn the reason for the warning.