Urinary and hair concentrations of trace metals in pregnant women from Northeastern British Columbia, Canada: a pilot study

Background Northeastern British Columbia (Canada) is an area of intense natural gas exploitation by hydraulic fracturing. Hydraulic fracturing can release contaminants, including trace metals, many of which are known developmental toxicants. To date, there is limited data on human exposure to contaminants in this region. Objective We aimed to examine trace metals in urine and hair samples from 29 Indigenous and non-Indigenous pregnant women from two communities (Chetwynd and Dawson Creek) in Northeastern British Columbia. Methods We recruited 29 pregnant women who provided spot urine samples over five consecutive days and one hair sample. We measured 19 trace metals in pooled urine samples from each participant and in the first 2 cm of hair closest to the scalp. We compared urinary and hair concentrations to those measured in women from the general population using data from the Canadian Health Measure Survey (CHMS), or reference values found in the literature for trace metals not measured in the CHMS. Results Median urinary (0.49 mu g/L) and hair (0.16 mu g/g) concentrations of manganese were higher in our participants than in the CHMS (<0.05 pg/L in urine) or reference population (0.067 mu g/g in hair). In hair, median values for barium (4.48 mu g/g), aluminum (4.37 mu g/g) and strontium (4.47 mu g/g) were respectively 16, 3, and 6 times higher compared with median values in a reference population. Concentrations of barium and strontium in hair were higher in self-identified Indigenous participants (5.9 and 5.46 mu g/g, respectively) compared to non-Indigenous participants (3.88 and 2.60 mu g/g) (p-values = 0.02 and 0.03). Conclusion Our results suggest higher gestational exposure to certain trace metals in our study population compared to reference populations.