Proper Etiquette: California Prop 65

California’s chemical law known as Proposition 65 requires the state to publish a list of chemicals known to cause cancer or birth defects or other reproductive harm.  The Prop 65 list was first published in 1987.

The list was updated on Oct. 28. The latest chemical added is tris(1,3-dichloro-2-propyl) phosphate (TDCPP).

Businesses have one year to organize warning and labeling systems if manufacturing or selling products in California that contain this chemical.  What does a label look like?

Here is a sample label under Prop 65.

(That particular label makes you think, doesn’t it?  It made me think..!)

At the end of this post is a current list of chemicals on the Prop 65 list. Scroll down to that section if desired, and download the list in PDF form, to keep for your records.

What is Prop 65?  California Prop 65 is actually the “Safe Drinking Water and Toxic Enforcement Act of 1986.”  It manifests as a list of chemicals known to the state of California to cause either cancer or reproductive toxicity.  The list:

  1. must be updated at least once a year
  2. products and facilities containing these chemicals are asked to clearly post warnings indicating the presence of these chemicals
  3. must be published for all to see

The Prop 65 list currently includes approximately 800 chemicals.

Now, included on the Prop 65 list are things we sometimes think of as benign, such as alcohol and aspirin.  Alcohol makes the list because it obviously can be toxic in sufficient amounts.  Aspirin makes the list because it has been shown to cause reproductive harm in fetuses if ingested by women in advanced stages of pregnancy.

So not all 800 chemicals on the Prop 65 list should be avoided at all costs (and in some cases they might save your life, as with aspirin to thin the blood, or, arguably, alcohol to get through holidays with the in-laws).  The important thing is that even if a chemical is safe for you, it might not be safe for others; some chemicals, eerily, do not seem to harm women at all but mess with the male developmental system in undesirable ways.

And, while a chemical may be safe for some uses, it may be toxic in certain doses, or in other uses, or for another gender.  The Prop 65 list seeks to publish the identity of every chemical that can be a danger.

Requirements for business under Prop 65. All chemicals on the Prop 65 list require businesses to act in some way, typically by posting a warning in the workplace, or by affixing a label on a product that contains, say, a globally-regulated toxin such as cadmium (which is also on the list).

Again, to see an ironic sample Prop 65 label, click here:  toxic breast cancer ribbon.  There you will see one of the great ironies of modern culture, and also the reason I look forward to coming to work in the morning.  The link goes to the image of a Fight Breast Cancer pink ribbon that you pin on your shirt, the packaging bears a warning that the ribbon itself contains chemicals that are known to cause cancer.

For those that don’t know, besides being a practicing CIH and Professional Chemical Engineer, I cofounded a company 15 years ago that provides manufacturers with software for tracking chemical ingredients from suppliers.  This type of software, the hope is, will maybe one day eradicate the need for such “ironic” labels on a Fight Cancer ribbon, because greener, non-toxic alternatives have been identified and used.

Warnings and labels under Prop 65. Businesses are required to provide a “clear and reasonable” warning before knowingly and intentionally exposing anyone to a listed chemical. This warning can be given by a variety of means, such as by labeling a consumer product, posting signs at the workplace, distributing notices at a rental housing complex, or publishing notices in a newspaper. Once a chemical is listed, businesses have 12 months to comply with warning requirements.

Proposition 65 also prohibits companies that do business within California from knowingly discharging listed chemicals into sources of drinking water. Once a chemical is listed, businesses have 20 months to comply with the discharge prohibition.

Exemptions. Businesses with fewer than 10 employees and government agencies are exempt from Proposition 65’s warning requirements and prohibition on discharges into drinking water sources. Businesses are also exempt from the warning requirement and discharge prohibition if the exposures they cause are so low as to create no significant risk of cancer or birth defects or other reproductive harm.

Risk thresholds. For chemicals that are listed as causing cancer, the “no significant risk level” is defined as the level of exposure that would result in not more than one excess case of cancer in 100,000 individuals exposed to the chemical over a 70-year lifetime. In other words, a person exposed to the chemical at the “no significant risk level” for 70 years would not have more than a “one in 100,000” chance of developing cancer as a result of that exposure.

CA Prop 65 “safe harbor numbers.” OEHHA develops numerical guidance levels, known as “safe harbor numbers,” for determining whether a warning is necessary or whether discharges of a chemical into drinking water sources are prohibited.

However, a business may choose to provide a warning simply based on its knowledge, or assumption, about the presence of a listed chemical without attempting to evaluate the levels of exposure.

Businesses do not file reports with OEHHA regarding what warnings they have issued and why, on that basis, or because of that, OEHHA is not able to provide further information about any particular warning, which is unfortunate. Instead, contact the business issuing the warning.

Enforcement and penalties. The California Attorney General’s Office enforces Proposition 65. Also, any district attorney or city attorney (for cities whose population exceeds 750,000) may enforce Proposition 65. So can an individual acting in “public interest” may enforce Proposition 65 by filing a lawsuit against a business alleged to be in violation.

Lawsuits have been filed by the Attorney General’s Office, district attorneys, consumer advocacy groups, and private citizens and law firms.  For enforcement information, contact the California Attorney General’s Office at (510) 622-2160 or visit

Penalties for violating Proposition 65 go up to $2,500 per violation per day if businesses fail to provide notices.

For more information on the Proposition 65 list of chemicals, contact OEHHA’s Proposition 65 program at (916) 445-6900, or visit

Download the list of chemicals on California’s Prop 65 list, no registration required.  Be advised there are 23 pages of this list; below is a snapshot of just the first page.  This list was updated Oct. 28. It’s a good document to download and keep for your records.

This entry was posted in Green Thoughts and tagged , , by Kal. Bookmark the permalink.

About Kal

Kal Kawar, CIH, PE, has a bachelor's in chemical engineering and a master's in industrial hygiene. His professional experience includes serving as staff industrial hygienist for IBM's New York semiconductor manufacturing facility, and as industrial hygienist for IBM’s US headquarters. Now executive vice president of Actio, Kal taps more than 20 years' worth of chemical engineering, industrial hygiene, and environmental engineering experience. His far-reaching expertise with global regulatory challenges created by EPA, TSCA, REACH, RoHS, WEEE – and hundreds of others – aid in developing Actio software solutions for MSDS management, raw material disclosure compliance, and product stewardship in a supply chain.