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Got Lead? Significant Changes to Proposition 65's Lead MADL May Be on the Horizon

August 2015

On July 2, the Center for Environmental Health (CEH), a consumer advocacy organization, petitioned California's Office of Environmental Health Hazard Assessment (OEHHA) to (1) repeal or amend Proposition 65 regulations pertaining to the Maximum Allowable Dose Level (MADL) for lead, and (2) clarify that the MADL for lead is a single-day exposure limit, and that averaging exposures over time is improper. OEHHA will hold a public hearing on October 9 to address CEH's petition. Based on information communicated by OEHHA, it is expected to respond with four significant and potentially controversial regulatory proposals.

Officially known as the "Safe Drinking Water and Toxic Enforcement Act of 1986," Proposition 65 (Prop 65) requires businesses to notify consumers of potential exposures to specifically-listed chemicals "known to" the State to cause cancer or birth defects or other reproductive harm. When a company "knowingly or intentionally" exposes consumers to Prop 65 listed chemicals, a warning is necessary unless a manufacturer can prove that its product fits within a statutory exemption. Thus, for example, no warning is required if the company can prove that exposure to a reproductive toxin will cause "no observable effect assuming exposure at one thousand (1,000) times the level in question." Health & Safety Code § 25249.10(c). To determine the level for which a warning is required, one must determine the maximum level of exposure to the chemical that will have "no observable effect" and then divide the number by 1,000 to determine the MADL. If it can be proven that any exposures to a listed reproductive toxin is below the MADL, the company need not provide a warning.

CEH's Position


The lead exemption was first established in 1989, and was based on a federal Occupational Safety and Health Administration (OSHA) permissible exposure limit of 500 micrograms per day. According to CEH, the current MADL of 0.5 micrograms per day is scientifically indefensible and too high to protect consumers against lead's reproductive effects. CEH contends that when the lead MADL was first adopted, OEHHA had a clear record establishing a reproductive effect from exposure to 500 micrograms of lead per day, and that subsequent research has reinforced this finding. As a result, CEH has requested that OEHHA repeal the lead MADL, or amend it to establish a lower level.


In addition, despite a recent court decision permitting otherwise, CEH has asked OEHHA to establish that the lead MADL reflects a single-day exposure limit, and that averaging over time is improper. In Envt'l Law Found v. Beech-Nut Nutrition Corp., et al., No. A139821 (Cal. Ct. App. Aug. 21, 2014), the defendants were permitted to average lead exposures over a 14-day period. According to CEH, OEHHA should supplant this decision by promulgating a regulation that the lead MADL is a single-day exposure limit.

OEHHA's Response

Based on current information, OEHHA is anticipated to respond with four regulatory proposals pertaining to: (1) a revised lead safe harbor (MADL), (2) "naturally occurring" allowances, (3) averaging levels of lead in product samples, and (4) averaging rates of exposure.

Revised Lead Safe Harbor: OEHHA is expected to replace the current MADL of 0.5 micrograms per day with a range of MADLs based on frequency of lead exposure. The resulting MADLs would, notionally, yield blood levels below 30 microgram of lead per deciliter of blood based on modeling that predicts how exposure to lead, over time, affects lead concentrations in the bloodstream. OEHHA anticipates that the MADL for daily lead exposure would be approximately 0.3 micrograms, a 40 percent decrease from the current MADL. Less-frequent exposure to lead would have correspondingly higher MADLs. For example, lead exposures once every 10 days (or even less frequently) would yield MADLs of roughly 3.0 micrograms. OEHHA believes that this approach is both scientifically more accurate and legally defensible.

"Naturally Occurring" Allowances: OEHHA would adopt allowances for lead in various California plant products based on data regarding background levels of lead in soil and uptake by plants. To establish these levels, OEHHA would review United States Geological Survey (USGS) and other scientific data regarding background levels and plant uptake. These levels would be deemed "naturally occurring" and, therefore, the only amount of lead that would be credited toward the new lead safe harbor MADLs would be the amount above these allowances. OEHHA recognizes that these levels would apply only to California-grown plant products, and not to products grown elsewhere. Nonetheless, OEHHA believes that the "naturally occurring" allowances would set target levels related to the requirement that contaminants be reduced to the "lowest level currently feasible."

Averaging of Product Samples: OEHHA would prohibit the averaging of levels of lead (or other Prop 65 listed chemicals) across different lots of food products. Rather, the level of contaminants in a particular lot of food would be determined by representative sampling from within that lot. One repercussion of this approach would be that a food company faced with a Prop 65 claim would need to show that each lot has contaminants below the Prop 65 level. While "lot" would be defined on a production basis—by reference to date or production codes—OEHHA does not intend to define "representative sampling."

Average Rate of Exposure: OEHHA would clarify that "average rate of exposure" is based on the arithmetic mean, not the geometric mean. This approach would apply to both carcinogens and reproductive toxins. The arithmetic mean adds individual data points and divides the sum by the number of data points. In contrast, the geometric mean, which is often used by public health agencies, disregards high and low data points that may skew the average.

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Kevin C. Mayer
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