Scientific & Technical Support: Proposition 65 - Safe Harbor Levels
California’s Office of Environmental Health Hazard Assessment (OEHHA)
establishes threshold levels, often called “Safe Harbor Levels,” which
trigger warning and discharge prohibition requirements under
Proposition 65.
OEHHA has published default Safe Harbor Levels for many
listed chemicals,
but others lack default values, even many years after the compounds have
been added to the list.
Companies
are required to provide “clear and reasonable warnings” and terminate
discharges one year after a chemical is listed under Proposition 65 if
exposures exceed the Safe Harbor Level. If OEHHA has not published a default
Safe Harbor Level, companies must establish their own Safe Harbor Level as
described in regulations.
TSG’s scientists have the toxicology expertise required to independently
establish Safe Harbor Levels (NSRL and MADL) that companies can use with
confidence in risk assessments until defaults are published by OEHHA.
Safe Harbor Levels are
described as follows:
Carcinogen Safe Harbor Levels are termed No Significant Risk Levels (NSRL).
They are based on the most
sensitive study meeting certain requirements and
calculations described in regulations for an exposure level that
results in
1 excess cancer in an exposed human population of 100,000
Reproductive Toxin Safe Harbor Levels are termed Maximum Allowable Dose
Level (MADL). They are based on
the most sensitive study meeting certain
requirements at a level that is 1,000 fold below the no observable effect
level (NOEL) of the study
TSG’s consultants are experienced at
calculating NSRL and MADL using regulations and underlying documentation.
Companies have used TSG's independent NSRL and MADL to comply with
Proposition 65 until default values are published by OEHHA. TSG's values and
documentation along with appropriate risk assessments establish a record of
Proposition 65 compliance that deters
litigation under the Act.
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