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Industry groups call for ditching of Prop 65 reprotox calculation amendments

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A broad industry coalition has pushed back on proposed changes to how exposures to reproductive toxicants are calculated under Proposition 65. They claim the amendments would "place additional and unjustified burdens solely on the backs of businesses".

The comments, spearheaded by the California Chamber of Commerce and co-signed by more than 200 organisations across a range of business sectors, come in response to an October proposal from California’s Office of Environmental Health Hazard Assessment (Oehha). This proposed making "clarifying" changes to how businesses calculate exposures to consumer products – a key step in determining whether a warning must be provided under the state’s right-to-know scheme.

Along with amendments aimed at calculating chemical intake from foods, the proposal seeks to specify that a company should use an arithmetic mean when calculating a level of exposure for an average user of a consumer product.

Oehha, which oversees Prop 65, says this will help businesses "to correctly determine the rate of intake or exposure for average users of the consumer product and properly decide whether a warning is required for a given exposure".

But in their comments industry argued the changes run against longstanding practice and would "exacerbate" the problem of businesses carrying the burden of proof in Prop 65 litigation.

More specifically, they said that defaulting to an arithmetic mean over other averaging measures is "inconsistent with sound principles of statistics and data evaluation". When the distribution of data is not bell-shaped, they said, the arithmetic mean will be more influenced by the highest and lowest values, and therefore become less representative of the actual average value.

"The obvious practical effect of the Arithmetic Mean Proposal would be to significantly increase the number of Proposition 65 warnings on products and the number of consumers who are unnecessarily receiving" them, the coalition said.

It also wrote that it "disagrees in the strongest possible terms" with Oehha's conclusion that the proposal will not have a significant adverse impact on businesses.

Oehha's proposals are not a 'clarification' to existing regulations, it said, but rather "present entirely new regulatory requirements that will directly affect businesses in their Proposition 65 compliance efforts, as well as placing additional obstacles to a defendant meeting its burden of proof in litigation".

The groups have urged Oehha to continue to allow case-by-case determinations for selecting an averaging measure, and to withdraw the proposal entirely.

Consumer advocates welcome changes

However, consumer advocates and frequent Prop 65 private enforcement plaintiffs back the planned changes.

The Center for Environmental Health applauded Oehha's proposal, noting that calculations using a geometric mean are often a level of magnitude less than the arithmetic mean. The proposed amendment, it said, "addresses this problem and specifies that the use of the geometric mean is not appropriate … This is the correct interpretation."

CEH also urged Oehha to adopt the arithmetic mean as the default averaging measure not just for reproductive toxicants, but for carcinogens, as well.

NGO As You Sow agreed in its comments that a geometric mean is "inappropriate, and that the arithmetic mean better products consumers".

But the group sought further clarifying changes, such as noting that an arithmetic mean is only appropriate in situations "where averaging is appropriate".

The Environmental Law Foundation, meanwhile, pressed Oehha to propose regulations that "tackle other lingering issues" in enforcement, such as the "inappropriate" use of averaging over time for exposures to teratogenic chemicals.

The consultation on the proposal closed on 3 December. Oehha must address substantive comments when finalising regulatory changes.

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