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Biomonitoring is used increasingly as an indicator and quantitative measure of exposure; however, there is a large gap in interpreting and communicating biomonitoring results to study participants. Two separate, national biomonitoring initiatives are under way in Canada; the household recruitment-based Canadian Health Measures Survey (CHMS) and the clinic recruitment-based Maternal-Infant Research on Environmental Chemicals (MIREC) Study. The CHMS provides participants with the option to receive all their results, but this option is not provided to MIREC participants. The approach to reporting results to participants depends on the availability of reference ranges and guidelines for which tissue concentrations may be interpreted as being elevated or associated with increased health risks, how participants are recruited, unique vulnerabilities of the population, legislation governing access to personal information, and decisions of research ethics committees. It is the researchers' responsibility to present the best case for their approach and, once the decision has been made, to inform participants about access to their results through the consent process.

Although it has been established that mercury (Hg) can be detected in single hair strands using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), calibration remains a challenge due to the lack of well-characterized matrix-matched standards. We concurrently evaluated two strategies for quantifying Hg signals in single hair strands using LA-ICP-MS. The main objective was to obtain time-resolved Hg concentrations in single hair strands of fish-eaters that would correspond to the changes of their body burden over time. Experiments were conducted using hair samples collected from 10 individuals. The first experiment involved the construction of a calibration curve with four powdered hair standard reference materials (SRMs) with a range of Hg concentrations (0.573-23.2 mg/kg). An internal standard, sulfur, as 34S, was applied to correct for ablation efficiency for both the hair strands and the SRMs. Results showed a linear relationship (R2 = 0.899) between the ratio of 202Hg to 34S obtained by LA-ICP-MS and the certified total Hg concentration in the SRMs. Using this calibration curve, average Hg concentrations of 10 shots within a 1-cm segment of a hair strand were calculated and then compared to the total Hg concentrations in the matched 1-cm segment as measured by cold vapor atomic absorption spectrometry (CV-AAS). A significant difference (p < 0.05) was observed. The difference could be attributed to the highly variable ablation/sampling process caused by the use of the laser on the hair powder SRM pellets and the difference in the physical properties of the SRMs. An alternative approach was adopted to quantify consecutive 202Hg to 34S ratios by calibrating the signals against the average Hg concentration of the matched hair segment as measured by CV-AAS. Consecutive daily Hg deposition in single hairs of fish eaters was determined. Results showed that apparent daily changes in Hg concentrations within a hair segment that corresponds to 1 month of hair growth. In addition, a significant decreasing or increasing time-trend was observed. The difference between the minimum and maximum Hg concentration within each individual corresponded to a change of 26-40%. Our results showed that LA-ICP-MS can be used to reconstruct time-resolved Hg exposure in micrometer segments of a single hair strand.

Hair samples continue to be used extensively for biomonitoring of mercury (Hg) exposure. Routine methods require a bundle of 100-150 hair strands and involve chemical digestion. Recently, Hg analyzers that combine combustion, gold amalgamation, and atomic absorption spectrometry (C-GA-AAS) became commercially available. This method was shown to provide quick and sensitive measurements in solid samples such as hair. The objective of this study was to validate C-GA-AAS for measuring total Hg in single hair strands as an alternative method for Hg biomonitoring. Hair samples from 12 women with a wide range of Hg exposure were obtained from two projects conducted in Brazil and Canada. A 1:1 relationship was observed between C-GA-AAS and the established cold vapor atomic absorption spectrometry (CV-AAS) for analysis of 1-cm segments from a bundle of hair. For individual hair variability, the average relative standard deviation (RSD) of Hg between hair strands was 6.5 +/- 2.8%, thus justifying the use of single hair strand for biomonitoring. With a limit of quantification of 0.10 ng of total Hg, a single hair strand can be used to assess monthly exposure. This technique will facilitate routine biomonitoring and thus help prevent Hg poisoning among the public.

Background: Manganese neurotoxicity is well documented in individuals occupationally exposed to airborne particulates, but few data are available on risks from drinking-water exposure. Objective: We examined associations of exposure from concentrations of manganese in water and hair with memory, attention, motor function, and parent- and teacher-reported hyperactive behaviors. Methods: We recruited 375 children and measured manganese in home tap water (MnW) and hair (MnH). We estimated manganese intake from water ingestion. Using structural equation modeling, we estimated associations between neurobehavioral functions and MnH, MnW, and manganese intake from water. We evaluated exposure–response relationships using generalized additive models. Results: After adjusting for potential confounders, a 1-SD increase in log10 MnH was associated with a significant difference of –24% (95% CI: –36, –12%) SD in memory and –25% (95% CI: –41, –9%) SD in attention. The relations between log10 MnH and poorer memory and attention were linear. A 1-SD increase in log10 MnW was associated with a significant difference of –14% (95% CI: –24, –4%) SD in memory, and this relation was nonlinear, with a steeper decline in performance at MnW > 100 μg/L. A 1-SD increase in log10 manganese intake from water was associated with a significant difference of –11% (95% CI: –21, –0.4%) SD in motor function. The relation between log10 manganese intake and poorer motor function was linear. There was no significant association between manganese exposure and hyperactivity. Conclusion: Exposure to manganese in water was associated with poorer neurobehavioral performances in children, even at low levels commonly encountered in North America. [ABSTRACT FROM AUTHOR]