Assessing the risk of lead exposure to children from drinking water in Metro Vancouver child care facilities

Abstract

Background: Environmental lead exposure has been a concern since the early 1970’s. With the reduction of airborne lead for inhalation, ingestion from food and water has become the major route of exposure leading to elevated blood lead levels. Previous research and the recent lead contamination of drinking water in Flint, Michigan demonstrate the vulnerability of young children and potential for exposure through drinking water. The purpose of this study was to assess and characterize the risk of lead contamination of drinking water for Metro Vancouver-area early childhood care facilities, and the effect of flushing fixtures as a control measure. Method: 91 drinking water samples were collected from various fixtures at 16 child care facilities at progressive time points to observe the effects of flushing and re-stagnation on total dissolved lead content. Analysis was performed using Varian AAS-240 coupled with GTA-120 graphite furnace atomic absorption spectroscopy. Results were analysed statistically using Excel 2010 and SAS/STAT® 14.2 software with SAS Studio 3.6 interface. Results: The mean (SD, min-max) lead concentrations of the water samples were 0.69 (2.32, 0.1-11.27) μg/L at zero minutes of flushing, 0.21 (0.44, 0.1-2.19) μg/L after one minute of flushing, 0.15 (0.17, 0.1- 0.87) μg/L after five minutes of flushing, 0.18 (0.17, 0.1 -0.64) μg/L after re-stagnation, and 0.31 (1.20, 0.1-11.27) μg/L overall. One outlier sample had a lead concentration of 11.27 μg/L, which exceeded Health Canada’s maximum allowable concentration of 10 μg/L. The decrease in mean lead concentration between zero minutes and one minute of flushing was statistically significant (p=0.0020). Conclusions: The results indicate that lead contamination of drinking water in child care facilities is present but below regulatory action levels under normal circumstances. The flushing of fixtures for at least one minute was shown to be effective in lowering lead concentrations further. Efforts should be taken to identify facilities at higher risk of lead contamination and to educate operators of flushing as an effective control measure.