California's Proposition 65 and Its Impact on Public Health

Burning fireplace or wood stove fuels such as natural firewood results in emission of carbon monoxide, soot, and other combustion by-products which are known by the State of California to cause cancer, birth defects, or reproductive harm.


Proposition 65, passed into law by the voters of California in 1986, was created with the intent of improving public health through reductions in the incidence of cancer and adverse reproductive outcomes that might result from exposure to potentially hazardous chemicals. To carry out this mission, Proposition 65 relies on a growing list of chemicals and substances believed to have the potential to cause cancer or deleterious reproductive effects in humans. The law strives to reduce human exposure by restricting discharges of listed chemicals into known drinking water sources, although the major activity of the Act has been in the area of warnings. Under the Act, a clear and reasonable warning must be given prior to a known and intentional exposure to a listed substance.

Proposition 65 places little emphasis on the major known risk factors for human cancer and reproductive toxicity. In contrast, many listed chemicals are included because of effects in laboratory animals, a not uncommon basis for chemical "lists" as long as the purpose (i.e., to produce an effect) and conditions (i.e., high-dose, chronic exposure) under which chemicals are tested are understood. Although Proposition 65 has established some safe exposure levels for listed chemicals based on conservative exposure assumptions, it does not include a robust program aimed at developing human exposure data for listed chemicals; rather, companies with listed chemicals have the onus of developing exposure information, which may or may not be challenged by the state.

Proposition 65 is essentially a "right-to-know" law, one which seeks to provide consumers with knowledge, but with little, if any, guidance on how to use and interpret the information provided. Furthermore, there are no mechanisms for evaluating the effectiveness of Proposition 65 in its mission to improve public health. It can be postulated that by failing to focus on the known risk factors associated with specific health effects (e.g., cancer) in humans, Proposition 65 has diminished the ability and effectiveness of public health efforts to address those known risks. Because various other states have considered similar initiatives, the American Council on Science and Health undertook this critique so that future efforts aimed at addressing public health and chemical exposures could benefit from the experience of Proposition 65.

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California's Proposition 65 and Its Impact on Public Health