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Proposition 65 - Compliance Implications

Business Objective

A product manufacturer with multiple warehouse and logistics operations in Southern California sought to evaluate their obligations under Proposition 65. Proposition 65 – The Safe Drinking Water and Toxic Enforcement Act of 1986 (Prop 65) relative to exposures to diesel exhaust from their truck operations. Recent litigation by Proposition 65 “bounty hunters” had centered on exposures to diesel exhaust, and the product manufacturer required a defensible technical analysis to assure that such warnings were – or were not - required. Failure to provide a prior “clear and reasonable warning” could result in a prolonged and expensive litigation.

Technical Approach

Given the number, variability and complexity of the client’s operations, and their relative proximity to residential homes, ALG developed a screening strategy to discern which facility posed with the greatest exposure risk to the public taking into account diesel truck traffic , chemical usage within the facility, and proximity to the nearest residential home. The screening analysis identified the candidate facility; a site visit was then performed to justify the site selection based on operations. Once the site selection was confirmed, ALG prepared an accurate emissions inventory for actual operations, which was then combined with agency-approved dispersion modeling to predict exposures to specific Proposition 65 compounds. ALG then applied agency-approved health risk assessments models to predict incremental risks posed by actual emissions from the facility. The results from the health risk assessment were then compared to OEHHA guideline for Proposition 65 warning obligations.


ALG successfully evaluated the client’s risk exposure to Proposition 65 warning thresholds for their most critical facility and the results from this evaluation was normalized for all their other facilities. This was the most cost-effective approach and provided reassurance to the client that no prior warning was required to address listed compounds emitted from their operations in California.

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