OEHHA Issues a Proposition 65 Safe Use Determination (SUD) for Dermal Exposure to BPA from Eyewear Products
Posted on Behalf of Natalie Binczewski.
On April 17, 2020, the California Office of Environmental Health Hazard Assessment (OEHHA) published a Safe Use Determination (SUD) for exposure to bisphenol A (BPA) in various polycarbonate eyewear products manufactured, distributed, or sold by member companies of The Vision Council (TVC). Polycarbonate plastic is manufactured through a polymerization reaction of BPA monomers, and residual BPA can migrate to the eyewear surface and come into contact with skin while wearing polycarbonate eyewear. Additionally, dermal exposure to BPA may occur during polycarbonate degradation caused by ultraviolet light exposure and humid conditions. OEHHA included BPA on the Proposition 65 (Prop65) list as a chemical known to the state to cause female reproductive toxicity and has a dermal Maximum Allowable Dose Level (MADL) of 3 micrograms per day (µg/day).
OEHHA conducted a screening-level exposure analysis to determine the upper-end estimate of dermal BPA exposure from wearing specified eyewear products. The estimate was based on analytical data from acetonitrile and artificial perspiration extraction studies submitted by TVC. Inhalation, hand-to-mouth, and oral exposures were assumed to be negligible since the concentration of BPA was below the limit of detection (LOD) in the artificial perspiration extraction studies. The LOD of the artificial perspiration extraction study was used as a conservative estimate of the maximum amount of BPA extracted per surface area. The maximum surface area of the face in contact with eyewear was used based on empirical measurements and the variability between eight eyewear users. It was also assumed that complete absorption of BPA occurred from contact with the skin and that there were 24 hours of contact based on the scenario of a professional working a 24-hour shift.
Uncertainties associated with this assessment were overall likely to cause an overestimation of the daily dose calculation. OEHHA noted that the use of the LOD of the artificial perspiration extraction studies and the 24-hour contact parameters were conservative assumptions. OEHHA also noted that data limitations, including BPA migration in facial skin, were the basis for assuming constant dermal transfer rate, continuous dermal contact, and complete dermal absorption. The agency recognized that the condition and age of the eyewear product and the concentration of sebum (oil) on the skin may affect BPA migration rates.
OEHHA calculated an estimated daily dose of 0.53 µg/day, below the MADL of 3 µg/day for BPA (dermal exposure from solid materials), and therefore the eyewear products do not require a Proposition 65 warning. It is noted that the SUD is specific to only the eyewear products manufactured, distributed, or sold by TVC member companies with a polycarbonate component (lenses, frames, temples, and/or nose pads) that contain acetonitrile extractable concentrations of BPA.