California’s Proposition 65

At The Science Standard, transparency is part of our standard. That includes helping you understand the warnings you may see on products sold in California.

Below, you'll find answers to common questions about California Proposition 65, what its warnings mean, and how it relates to dietary supplements.

What is California Proposition 65?

California Proposition 65, formally known as the Safe Drinking Water and Toxic Enforcement Act of 1986, is a California law designed to inform consumers about potential exposure to chemicals the state has identified as causing cancer, birth defects, or other reproductive harm.

The State of California maintains and regularly updates a list of these chemicals. Businesses selling products in California may be required to provide a warning when use of a product could result in exposure to a listed chemical above applicable levels.

Proposition 65 warnings aren't limited to supplements. They can be found on a wide range of consumer products and at businesses and locations throughout California.

What chemicals are included under Proposition 65?

The Proposition 65 list includes a broad range of naturally occurring and synthetic chemicals. Some may be found in foods, dietary supplements, household products, building materials, and other everyday items.

Certain listed substances, including heavy metals such as lead, cadmium, and arsenic, occur naturally in the environment. Plants can absorb naturally occurring elements from soil and water, which means trace amounts can sometimes be present in botanical, mineral, and other naturally derived ingredients.

Because Proposition 65 requirements are based on exposure to listed chemicals, some products may require a warning even when those substances were not intentionally added to the product.

Does Proposition 65 apply outside California?

Proposition 65 is a California law. However, companies located outside California can still be subject to its requirements when their products are sold to consumers in California.

As a result, you may see a Proposition 65 warning associated with a product purchased or shipped to California even though the same warning isn't required in other states.

Does a Proposition 65 warning mean a product is unsafe?

Not necessarily.

A Proposition 65 warning is intended to notify California consumers about exposure to a chemical on the state's Proposition 65 list. The presence of a warning is not, by itself, a determination that a product is unsafe.

Proposition 65 has its own exposure thresholds and warning requirements, which can differ from standards established by federal agencies and other regulatory bodies.

The purpose of the warning is to provide California consumers with information so they can make their own informed purchasing decisions.

How are Proposition 65 warning levels determined?

Proposition 65 uses different approaches for chemicals associated with cancer and those associated with reproductive or developmental harm.

For chemicals listed as carcinogens, California establishes a "No Significant Risk Level" (NSRL). Generally, this represents an exposure level calculated to result in no more than one additional case of cancer among 100,000 people exposed at that level every day over a 70-year lifetime.

For chemicals associated with reproductive harm, California may establish a "Maximum Allowable Dose Level" (MADL). This is generally calculated from a level at which no observable reproductive effect has been identified, with an additional 1,000-fold safety factor applied.

When exposure to a listed chemical exceeds an applicable safe harbor level, a Proposition 65 warning may be required.

Why can dietary supplements contain Proposition 65-listed substances?

Some ingredients used in dietary supplements come from plants, minerals, and other natural sources. Because elements such as lead, cadmium, and arsenic occur naturally in soil, water, and the environment, trace amounts can sometimes be present in agricultural and botanical ingredients.

This doesn't necessarily mean these substances were added during manufacturing. In some cases, they are naturally present in the raw materials from which the ingredient is derived.

Proposition 65 evaluates exposure to listed chemicals, including certain naturally occurring substances, under requirements specific to California.

What is The Science Standard doing about Proposition 65?

Quality and transparency are fundamental to The Science Standard.

Our products undergo four rounds of testing using accredited third-party laboratories to verify identity, potency, and purity. Our quality testing includes screening designed to identify contaminants and verify that finished products meet our established specifications.

We evaluate our products and testing data against applicable regulatory requirements, including California Proposition 65. When a Proposition 65 warning is required for a product sold in California, we provide the appropriate warning.

A Proposition 65 warning doesn't change our commitment to quality. It reflects our commitment to transparency and to complying with the requirements that apply wherever our products are sold.

You can read more about The Science Standard's quality standards here.

Why might I see a warning on one product but not another?

Proposition 65 requirements are based on exposure to specific listed chemicals, not simply on the type of product.

Ingredient sources, serving sizes, naturally occurring trace elements, and the applicable exposure threshold can all affect whether a warning is required. As a result, one dietary supplement may require a Proposition 65 warning while another does not.

Where can I learn more about Proposition 65?

For additional information about California Proposition 65, including the current chemical list, warning requirements, and safe harbor levels, visit the California Office of Environmental Health Hazard Assessment (OEHHA) or the California Attorney General's Office.