No abstract

The effect of the chloride‐to‐sulfate mass ratio (CSMR) on lead leaching from 50:50 lead–tin solder galvanically coupled to copper in stagnant conditions was examined using bench‐scale testing and data from water utilities. The CSMR was significantly altered by coagulant changeover, blending of desalinated seawater, anion exchange, and NaCl brine leaks from onsite hypochlorite generators. Consistent with previous experiences, increasing the CSMR to the range of 0.1 to 1.0 produced dramatic increases in lead leaching from lead–tin solder galvanically coupled to copper. Before implementing any treatment changes that could increase the CSMR, utilities may want to use the protocol described in this article to ascertain the relative effect of the changes on lead corrosion.

As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and the copper. If the resulting galvanic current exceeds about 2 μA/cm(2), a highly corrosive microenvironment can form at the solder surface, with pH < 2.5 and chloride concentrations at least 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface, and contributing to lead contamination of potable water supplies. The total mass of lead corroded was consistent with predictions based on the galvanic current, and lead leaching to water was correlated with galvanic current. If the concentration of sulfate in the water increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated.

The effect of added cupric ions (0 mg/L to 5 mg/L Cu +2 ) on possible deposition corrosion of lead pipe was investigated in bench-scale experiments under flowing and stagnant water conditions. Under stagnation the presence of cupric ions in the water feeding lead pipes marginally increased lead release into the water, but under continuous recirculation it could increase lead release by orders of magnitude. Other benchscale experiments investigated galvanic corrosion between lead and copper pipes under stagnation, confirming that water chemistry (particularly the chloride-to-sulfate mass ratio [CSMR]) is a controlling factor in either "strengthening" galvanic corrosion and increasing water lead contamination by orders of magnitude (high CSMR water) or "weakening" the galvanic effect with less but still significant contribution to water lead contamination (low CSMR water). Longitudinal water pH measurements along the length of the galvanic rigs revealed a significant pH drop close to the lead:copper junction at relatively short stagnation times in high CSMR water, which is consistent with the observations of higher lead leaching and higher galvanic current measured in that situation.

Background Personal care products may contain many chemicals, some of which are suspected endocrine disrupters. This is an important source of chemical exposure for women, but little is known about how chemical exposure differs among different races/ethnicities. Objective This study examines differences in personal care product use among Black, Latina, Vietnamese, Mixed Race, and White women in California. Methods We used a community-based participatory process to create and administer a personal care product usage survey to 321 Black, Latina, Vietnamese, Mixed Race, and White women. We used multivariate regression models with pairwise comparisons to examine the frequency of product use by race/ethnicity. Results We found distinct trends of personal care product use by race/ethnicity: Latina women typically used makeup most frequently; Black women used certain hair products or styles most frequently; and Vietnamese women were most likely to use facial cleansing products compared to other races/ethnicities. Latina and Vietnamese women were less likely to try to avoid certain ingredients in their products. Significance These findings can help estimate disparities in chemical exposure from personal care product use and complement future research on health inequities due to chemical exposures in the larger environmental and social context.