State of California Proposition 65
Safe Drinking Water and Toxic Enforcement
Act of 1986
The State of California Safe Drinking Water and Toxic Enforcement Act of 1986, known as Proposition 65 (Prop 65), requires products sold in California that could, based on the presence of certain substances, pose a risk to either reproductive harm or increased cancer occurrence to carry a warning to consumers.
Proposition 65 requires the Governor of California to publish a list of substances that are known to the State of California to cause cancer, birth defects or other reproductive harm.
Progesterone, as well as other human hormones, is on this list. As such, products containing any of these substances are subject to carrying an appropriate and specific warning label.
Under California’s Proposition 65 list, progesterone creams manufactured and/or distributed in California are required by law to carry a warning on all labels as follows:
"WARNING: This Product Contains A Chemical Known To The State of California To Cause Cancer."
Proposition 65 imposes certain requirements that apply to chemicals that appear on this list. These requirements are designed to protect California’s drinking water sources from contamination by these chemicals, to allow California consumers to make informed choices about the products they purchase, and to enable residents or workers to take whatever action they deem appropriate to protect themselves from exposures to harmful chemicals.
Currently, there are over seven hundred substances on the Prop 65 list. Many of these substances are naturally or commonly occurring in the environment. They can be found in many natural products - including foods and cosmetics.
Natural progesterone is such a substance.
Although Prop 65 states "known", in practice, substances added to the list are those that could, under certain circumstances, be reasonably thought of as posing a cancer risk based on the interpretation of existing scientific information, such as animal studies, at the time of inclusion.
Substances can be added to or removed from the Prop 65 list by various mechanisms, such as declaration by an “authorative body” or by scientific testing. Whether one of these other sources has engaged in sound scientific practices before designating a substance as a carcinogen or reproductive toxicant is often the subject of much debate.
Delisting progesterone is apparently very costly. So, for the time being, progesterone remains on the Prop 65 list.
Why isn’t synthetic HRT made to carry a Prop 65 warning if estrogens and artificial progestins are on the list? Well, because prescriptions given to consumers are excluded [from carrying warnings] on the grounds your physician and/or pharmacist act as "informed intermediaries".
Peter McGaw, Of Counsel to Archer Norris defends clients in regulatory, remediation, personal injury, and property damage cases arising out of environmental legislation, including California Proposition 65. In his “pull no punches” article ‘Proposition 65: A National Problem‘ he writes, “Although Proposition 65 is intended to prevent harm to individuals, the “enforcer” is not required to demonstrate that any actual harm has occurred.”
According to Mr McGaw, there is substantial concern about the efficacy of the warning. The proliferation of “generic” Proposition 65 warning labels on products and in areas around the state is seen by many as both over-warning (where there is no significant risk) and under-warning (where the user cannot distinguish between a significant risk and an insignificant risk), yet the Bounty Hunters are adamant that adding “qualifications” to the standard language is not permitted.
Proposition 65 does not apply to businesses with fewer than ten employees. Be careful though. “Employees” includes temporary and part-time employees. If, even counting temporary and part-time employees, your business has fewer than ten employees, consider yourself lucky. You get a pass on Proposition 65 liability, for now. Just don’t grow!
Small size is no guarantee of safety: in fact, many of the private enforcers prefer to target the small operation that does not have the financial ability to mount a strong defence.
To add some perspective here:
- Bioidentical progesterone is not listed as a potential carcinogen in any other state in the USA.
- Bioidentical progesterone is routinely used in fertility clinics around the globe to help sustain pregnancy in high-risk situations.
- Bioidentical progesterone is carcino-protective; it helps counteract the carcinogenic effects of estrogen.
Experts agree, our cumulative exposure to estrogen during our lifetime is the single most important risk factor for breast cancer. And that the body’s natural anti-estrogen is progesterone. Medical professionals working in the bioidentical HRT arena concur progesterone is carcino-protective and helps counteract the carcinogenic effects of estrogen.
Human-identical progesterone is routinely used in fertility clinics around the world, and I’m guessing this would include the State of California. Now, you’ve got to ask the obvious question - why would governing medical authorities sanction prenatal exposure to a supposedly carcinogenic hormone at the very point where life begins if they genuinely believed human-identical progesterone to be linked to cancer?
Progesterone is needed to prepare the uterus lining for embryo implantation and helps maintain the pregnancy until the placenta is developed, a process known as luteal phase support. Where progesterone levels are low, the drug Crinone (containing bioidentical progesterone) can be used as a supplement during assisted reproductive technology (ART) cycles and into early pregnancy.
Crinone’s Product Information Sheet does include the following warning, "Nonclinical toxicity studies to determine the potential of Crinone to cause carcinogenicity or mutagenicity have not been performed." So I guess, once again, we’re left to plough our way through fact and fiction and draw our own conclusions!
If you currently access the Natural-Progesterone-Advisory-Network.com website, then you already know that there is a great deal of medical evidence and clinical studies that validate the safety and efficacy of progesterone.
Should you - the consumer - have any questions concerning Prop 65 and the cream you are using or have recently purchased, I urge you to speak with your cream manufacturer or distributor for clarification and reassurance.
In light & love,

Catherine P. Rollins
Director, Making Plans Pty Ltd
www.natural-progesterone-advisory-network.com