Urinary arsenic concentrations and speciation in residents living in an area with naturally contaminated soils

A cross sectional study was carried out to evaluate arsenic exposure of residents living in an area with a soil naturally rich in arsenic (As), through urinary measurements. During the summer of 2007, 322 people aged over 7 years and resident in the study area for at least 4 days prior to the investigation were recruited. The sum of urinary inorganic arsenic and metabolites (iAs+MMA+DMA) and speciation were determined by graphite furnace atomic absorption spectrometry and high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry, respectively. Geometric means levels of iAs+MMA+DMA were 3.6 microg/L or 4.4 microg/g creatinine. The percent of DMA, As(III) and MMA contribution to urinary arsenic concentrations was respectively 84.2%, 12% and 3.7%. We found significant associations between urinary arsenic concentrations and the consumption of seafood (p=0.03), the consumption of wine (p=0.03) and beer (p=0.001), respectively 3 and 4 days before the investigation. When we focus on the various species, As(V) was rarely detected and DMA is the predominant metabolite composing the majority of measurable inorganic-related As in the urine. Considering the percent of DMA contribution to iAs+MMA+DMA urinary concentrations, almost half of the subjects had 100% of DMA contribution whatever the concentration of urinary As whereas the others had a lower DMA contribution, between 39 and 90%. Arsenic levels reported in this original study in France were between 2 and 4 times lower than in other studies dealing with iAs+MMA+DMA levels associated with soil arsenic exposure. Arsenic levels were similar to those observed in unexposed individuals in European countries, although 10% were above the French guideline values for the general population.