Warning to California Residents

Prop 65

In California, signs of Proposition 65 are everywhere, literally. Everywhere you turn (the gas station, the coffee shop, even the beach), there are signs to notify you that you may come into contact with a chemical known to cause reproductive harm or cancer.

What is Proposition 65 (also called "Prop 65")?

In 1986, California voters approved an initiative to address concerns about unintended exposure to toxic chemicals. Proposition 65 (also known as the Safe Drinking Water and Toxic Enforcement Act of 1986) requires the State to publish a list of chemicals known to cause cancer, birth defects or other reproductive harm when repeated exposure to toxic thresholds occur. The Governor of California is required to have the list updated yearly; currently there are over 800 chemicals on this list.

Does this law apply everywhere?

The “Prop 65” warnings are only required under California law. Prop 65 standards are among the most stringent standards in place anywhere and are often far more stringent than federal standards.

What kinds of substances require warnings?

Proposition 65 regulates substances officially listed by California as having a 1 in 100,000 chance of causing cancer over a 70-year period or birth defects or other reproductive harm in two ways.

  1. The first statutory requirement of Proposition 65 prohibits businesses from knowingly discharging listed substances into drinking water sources, or onto land where the substances can pass into drinking water sources.
  2. The second prohibits businesses from knowingly exposing individuals to listed substances without providing a clear and reasonable warning.

The list contains a wide range of naturally occurring and synthetic chemicals that are known to cause cancer or birth defects or other reproductive harm when exposure thresholds are met. These chemicals include additives or ingredients in pesticides, common household products, food, drugs, dyes, or solvents. Listed chemicals may also be used in manufacturing and construction,or they may be byproducts of chemical processes, such as motor vehicle exhaust.

Californians are no stranger to these warnings, as they are posted in hotels, gas stations, and coffee shops and are found on many products they encounter on a daily basis.

Should I be concerned?

A Prop 65 warning does not mean that the use of an individual product will cause cancer or reproductive harm when used as directed. There continues to be much debate over what a toxic level or a cumulative toxic level of each substance is. For example, for reproductive toxins, the stated level requiring a warning label is 1,000 times lower than the lowest level at which animal studies reported no reproductive health effect. At this dose, the risk of harm may be very low, yet a product still requires the Prop 65 warning.

Are dietary supplements labeled with the Prop 65 warning unsafe?

While many substances that require labeling are straightforward, there are others that might surprise you. One example of this is vitamin A (retinol/retinyl esters), which requires labeling if it is above a certain dosage.  Additionally, many plant-based foods, even when grown organically, can contain lead and mercury due to absorbing low amounts that are naturally occurring in soil. These will require a label as well if there’s a chance they contain any heavy metals.

One example of this is lead. The proposition 65 limit for lead is 0.5 mcg per day. The US Environmental Protection Agency’s (EPA) safe limit for lead in drinking water is 15 mcg/L per day. To provide some perspective on how some of the standards set by Proposition 65 are extremely low, many foods contain naturally-occurring lead from the soil it was grown in. One ounce of dark chocolate can contain about 0.6 mcg of lead, which would exceed the 0.5 mcg/day safe limit of lead by Prop 65 standards. And who can stop at one ounce!

What is the required warning?

The State of California requires dietary supplement companies to label products containing ingredients on their list with the following:



Consuming this product can expose you to chemicals including {Name of chemicals}, which is (are) known to the State of California to cause cancer and {Name of chemicals}, which is (are) known to the State of California to cause birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov

If you have questions about Proposition 65 or how it affects your products, please contact our Customer Service customerservice@mushroomwisdom.com .

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