CA Prop 65

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that one or more listed chemicals is present. By law, a warning must be given for listed
chemicals unless exposure is low enough to pose no significant risk of cancer or is
significantly below levels observed to cause birth defects or other reproductive harm.
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.
For chemicals that are listed as causing birth defects or reproductive harm, the “no
observable effect level” is determined by identifying the level of exposure that has been
shown to not pose any harm to humans or laboratory animals. Proposition 65 then
requires this “no observable effect level” to be divided by 1,000 in order to provide an
ample margin of safety. Businesses subject to Proposition 65 are required to provide a
warning if they cause exposures to chemicals listed as causing birth defects or
reproductive harm that exceed 1/1000
th
of the “no observable effect level.”
To further assist businesses, OEHHA develops numerical guidance levels, known as
“safe harbor numbers” (described below) 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. Because businesses do not file reports with OEHHA
regarding what warnings they have issued and why, OEHHA is not able to provide
further information about any particular warning. The business issuing the warning
should be contacted for specific information, such as what chemicals are present, and
at what levels, as well as how exposure to them may occur.
What are safe harbor levels?
As stated above, to guide businesses in determining whether a warning is necessary or
whether discharges of a chemical into drinking water sources are prohibited, OEHHA
has developed safe harbor levels. A business has “safe harbor” from Proposition 65
warning requirements or discharge prohibitions if exposure to a chemical occurs at or
below these levels. These safe harbor levels consist of No Significant Risk Levels for
chemicals listed as causing cancer and Maximum Allowable Dose Levels for chemicals
listed as causing birth defects or other reproductive harm. OEHHA has established over
300 safe harbor levels to date and continues to develop more levels for listed
chemicals.
What if there is no safe harbor level?
If there is no safe harbor level for a chemical, businesses that expose individuals to that
chemical would be required to provide a Proposition 65 warning, unless the business
can show that the anticipated exposure level will not pose a significant risk of cancer or
reproductive harm. OEHHA has adopted regulations that provide guidance for
calculating a level in the absence of a safe harbor level. Regulations are available at