Page 7 - Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada

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Appendix A: Limits of detection

Laboratory analyses of environmental chemicals and creatinine were performed at analytical laboratories within Health Canada, l'Institut national de santé publique du Québec, and the ALS Laboratory Group. Laboratories developed standardized operating procedures for the analytical methods used to measure environmental chemicals or their metabolites in biological samples. The limit of detection (LOD) is defined as the lowest concentration of the analyte whose analytical response is measured to be greater than the noise level with 99% confidence and evaluated using U.S. Environmental Protection Agency methodology (EPA, 2015).

References

• EPA (U.S. Environmental Protection Agency) (2015). Definition and procedure for the determination of the method detection limit – Revision 1.11, Federal Regulation 40 CFR 136 Appendix B. U.S. Environmental Protection Agency, Washington, DC.

Appendix B: Conversion factors

Units of measurement are important. Results are reported here using standard units; however, units can be converted using the conversion factors presented below for comparison of data with other data sets.

For concentrations of environmental chemicals in blood and urine, data can be converted from μg/L to μmol/L using the molecular weight (MW) of the chemical and the formula:

Y µmol/L = X µg/L × conversion factor (CF), where the CF is equivalent to 1/MW.

For concentrations of environmental chemicals in hair, data can be converted from μg/g to μmol/g using the MW of the chemical and the formula:

Y µmol/g = X µg/g × CF, where the CF is equivalent to 1/MW.

Appendix C: Creatinine

Appendix D: Biomonitoring of metals and trace elements in hair

Overview

The first nationally representative data for 25 metals and trace elements in hair of Canadians are presented here. These data were collected between January 2016 and December 2017 as part of cycle 5 of the Canadian Health Measures Survey (CHMS) from approximately 2,000 Canadians aged 20–59 years at 16 sites across Canada.

The metals and trace elements measured in hair of individual respondents in cycle 5 of the CHMS are listed in Table D-1.

Metals and trace elements can accumulate in hair as it grows, making it a useful matrix to measure both recent and long-term exposures. Chemicals can enter hair through internal and external exposure. Internal exposures (via inhalation, ingestion, etc.) are incorporated into growing hair through the blood supply following absorption of a chemical into the body. External exposures result in deposition onto hair from sources such as air, water, and product use. The amount of a chemical measured in hair indicates the total amount resulting from both internal and external exposures. As such, measurements in hair do not provide information about the source or route of the exposure.

Laboratory Analyses

Metal and trace element analyses in hair were performed at the Centre de toxicologie du Québec (CTQ), Institut National de Santé Publique du Québec (INSPQ), Québec, Canada (INSPQ, 2018). Hair samples were collected from the occipital region of the head by cutting strands close to the scalp, clearly identifying the proximal (scalp) end of the samples. A minimum natural hair length of 2 cm was required and approximately 100 strands of full-length hair were collected. Segments of hair 2 cm to 3 cm in length were cut from the proximal end of the sample and digested overnight in pressurized Teflon bombs at 120°C under acidic conditions (concentrated nitric acid). The digest was then diluted in a solution of L-cysteine and gold, and analyzed for metals and trace elements using inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS method employed a PerkinElmer NexION 300S with a ESI-SC-2 autosampler. Results are expressed on a wet-weight basis. The analytical method was fully validated for clinical and monitoring purposes following ISO 17025 guidelines. Internal quality control was ensured by analyzing certified hair reference materials from the Japanese National Institute for Environmental Studies and the European Commission's Institute for Reference Materials and Measurements as well as non-certified materials from the Québec Multi-element External Quality Assessment Scheme (QMEQAS). External quality and accuracy of the analytical method was assessed by participating in interlaboratory comparison programs, including QMEQAS.

Biomonitoring in Canada

Of the 25 metals and trace elements measured in hair as part of the CHMS, existing Canadian hair biomonitoring data were identified for 15 of them. These metals and trace elements include aluminum, antimony, arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium, uranium, vanadium, and zinc. The majority of the studies reporting metals and trace elements in hair predate the 1990s; most were focused on either children or occupational and industrial exposures (Chattopadhyay and Jervis, 1974; Gibson and Dewolfe, 1979; Gibson et al., 1985; Gibson et al., 1989; Jervis et al., 1977; Moon et al., 1986; O'Toole et al., 1972; Randall and Gibson, 1989; Vanderkooy and Gibson, 1987). The remaining 10 metals and trace elements (barium, beryllium, bismuth, lithium, molybdenum, platinum, silver, tellurium, thallium, and thorium) were not identified in hair biomonitoring literature in Canada for any time period. This summary focuses on recent data (1990 onward) available for a subset of metals and trace elements, namely arsenic, manganese, mercury, selenium, uranium, and zinc.

Of the six metals and trace elements for which there are recent Canadian biomonitoring data in hair, mercury is the most studied. Concentration of mercury in hair and blood indicates methylmercury exposure, while urine concentrations generally indicate inorganic mercury exposure. The normal level of mercury in hair is 1 µg/g to 2 µg/g, but people who consume fish one or more times per day may have mercury levels in hair exceeding 10 µg/g (UNEP/WHO, 2008). In Canada, a comprehensive overview of studies measuring mercury in hair is presented in the Canadian Mercury Science Assessment Report (CMSAR) (Environment and Climate Change Canada and Health Canada, 2016). The geometric mean hair mercury levels presented in the CMSAR ranged from 0.23 µg/g to 2.8 µg/g for various groups in the Canadian adult population. The highest concentrations were reported for James Bay sport fishermen (Bélanger et al., 2008). In Northern Canada, a biomonitoring project was carried out among Dene/Métis communities of the Dehcho region of the Northwest Territories from 2016 to 2018 (Ratelle et al., 2018). The geometric mean concentration for mercury in hair was 0.39 μg/g based upon measures from 279 participants (aged six years and older).

Health Canada has established a methylmercury hair guidance value of 6 µg/g for the general adult population; levels below this value are considered within the normal acceptable range (Health Canada, 2004). For individuals under 18 years of age, pregnant women, and women of childbearing age (under 50 years of age), Health Canada has proposed a provisional methylmercury blood guidance value of 8 µg/L for the protection of the developing nervous system, which is equivalent to a methylmercury hair guidance value of 2 µg/g (Legrand et al., 2010).

Studies measuring levels of arsenic, manganese, selenium, uranium, or zinc in hair have been conducted in various locations and subpopulations in Canada since 1990. Studies examining arsenic in hair reported average, geometric mean, or median levels ranging from 0.018 to 0.15 µg/g in adults (Spallholz et al., 2005; Nieboer et al., 2017; Normandin et al., 2014). Studies measuring levels of manganese in hair have focused on children (6 to 13 years of age) and reported geometric mean levels ranging from 0.29 to 0.70 µg/g (Bouchard et al., 2011; Dion et al., 2018; Ntihabose et al., 2018). Selenium in hair was reported to have a mean concentration of 0.546 µg/g in adults (Spallholz et al., 2005). Levels of uranium measured in hair from a small sample of active and retired Canadian Forces personnel were reported to range from 0.0018 µg/g to 0.354 µg/g (Ough et al., 2002). A potential exposure source in this study may be depleted uranium munitions resulting from active duty overseas. Lastly, a mean level of zinc in hair of 115 µg/g was reported in children two to six years old (Vaghri et al., 2008).

Data Analysis

Tables D-2 to D-26 present each metal and trace element measured in hair in cycle 5. The data tables include the sample size (n), detection frequency, geometric mean (GM), and the 10^th, 50^th, 90^th, and 95^th percentiles, with associated 95% confidence intervals (CIs). For each chemical, results are presented for the total population as well as by sex and age group. While the numbers of male and female respondents were similar, the minimum requirement of 2 cm of natural hair length resulted in a greatly reduced final male sample size. Measurements that fell below the LOD for the laboratory analytical method were assigned a value equal to half the LOD. If the proportion of results below the LOD was greater than 40%, GMs were not calculated. Percentile estimates that are less than the LOD are reported as <LOD. LOD values for each chemical are provided alongside their respective data tables and in Appendix A. Conversion factors to assist in the comparison of data from other studies that report different units are provided in Appendix B. Finding a measurable amount of a chemical in hair is an indicator of exposure to that chemical and does not necessarily mean that an adverse health effect will occur.

References

• Arbuckle, T.E., Fraser, W.D., Fisher, M., Davis, K., Liang, C.L., Lupien, N., Bastien, S., Velez, M.P., Von Dadelszen, P., Hemmings, D.G., et al. (2013). Cohort profile: The maternal-infant research on environmental chemicals research platform. Paediatric and Perinatal Epidemiology, 27 (4), 415–425.
• Bélanger, M.C. Mirault, M.E., Dewailly, E., Plante, M., Berthiaume, L., Noël, M. and Julien, P. (2008). Seasonal mercury exposure and oxidant-antioxidant status of James Bay sport fishermen. Metabolism, 57 (5), 630–636.
• Bouchard, M.F., Sauvé, S., Barbeau, B., Legrand, M., Brodeur, M., Bouffard, T., Limoges, E., Bellinger, D.C. and Mergler, D. (2011). Intellectual impairment in school-age children exposed to manganese from drinking water. Environmental Health Perspectives, 119(1), 138–143.
• Chattopadhyay, A. and Jervis, R.E. (1974). Hair as an indicator of multielement exposure of population groups. Proceedings of Symposium on Trace Substances in Environmental Health, 31–38.
• Dion, L.-A., Saint-Amour, D., Sauvé, S., Barbeau, B., Mergler, D. and Bouchard, M.F. (2018). Changes in water manganese levels and longitudinal assessment of intellectual function in children exposed through drinking water. NeuroToxicology, 64, 118–125.
• Environment and Climate Change Canada and Health Canada (2016). Mercury and human health (Chapter 14), Canadian Mercury Science Assessment Report. Government of Canada, Ottawa, ON. Retrieved December 6, 2018.
• Gibson, R.S. and Dewolfe, M.S. (1979). The zinc, copper, manganese, iodine, vanadium and iodine content of hair from 38 Canadian neonates. Pediatric Research, 13, 959–962.
• Gibson, R.S., Ferguson, E.F., Vanderkooy, P.D.S. and MacDonald, A.C. (1989). Seasonal variations in hair zinc concentrations in Canadian and African children. The Science of the Total Environment, 84, 291–298.
• Gibson, R.S., Martinez, O.B. and MacDonald, A.C. (1985). The zinc, copper, and selenium status of a selected sample of Canadian elderly women. Journals of Gerontology, 40(3), 296–302.
• Health Canada (2004). Mercury – Your health and the Environment: A Resource Tool. Minister of Health, Ottawa, ON. Retrieved February 27, 2019.
• INSPQ (Institut national de santé publique du Québec) (2018). Méthode d'analyse pour doser les métaux et autres éléments dans les cheveux et les ongles par ICP-MS NexION 300S (M-599-04), format condensé pour ECMS. Laboratoire de toxicologie, Québec, QC.
• Jervis, R.E., Tiefenbach, B. and Chattopadhyay, A. (1977). Scalp hair as a monitor of population exposure to environmental pollutants. Journal of Radioanalytical Chemistry, 37, 751–760.
• Legrand, M., Feeley, M., Tikhonov, C., Schoen, D., and Li-Muller, A. (2010). Methylmercury blood guidance values for Canada. Canadian Journal of Public Health, 101(1), 28–31.
• Moon, J., Smith, T.J., Tamaro, S., Enarson, D., Fadl, S., Davison, A.J. and Weldon, L. (1986). Trace metals in scalp hair of children and adults in three Alberta Indian villages. Science of the Total Environment, 54-, 107–125.
• Nieboer, E., Martin, I.D., Liberda, E.N., Dewailly, E., Robinson, E. and Tsuji, L.J.S. (2017). Body burdens, sources and interrelations of selected toxic and essential elements among the nine Cree First Nations of: Eeyou Istchee, James Bay region of northern Quebec, Canada. Environmental Science: Processes and Impacts, 19 (5), 727–741.
• Normandin, L., Ayotte, P., Levallois, P., Ibanez, Y., Courteau, M., Kennedy, G., Chen, L., Le, X.C. and Bouchard, M. (2014). Biomarkers of arsenic exposure and effects in a Canadian rural population exposed through groundwater consumption. Journal of Exposure Science and Environmental Epidemiology, 24, 127–134.
• Ntihabose, R., Surette, C., Foucher, D., Clarisse, O. and Bouchard, M.F. (2018). Assessment of saliva, hair and toenails as biomarkers of low level exposure to manganese from drinking water in children. NeuroToxicology, 64, 126–133.
• O'Toole, J.J., Clark, R.G., Malaby, K.L. and Trauger, D.L. (1972). Environmental trace element survey at a heavy metals refining site. Pp 172-182 IN Nuclear methods in environmental research (eds. Vogt, J.R., Parkinson, T.F and Carter R.L.), University of Missouri-Columbia, Columbia, MO.
• Ough, E.A., Lewis, B.J., Andrews, W.S., Bennett, L.G.I., Hancock, R.G.V. and Scott, K. (2002). An examination of uranium levels in Canadian Forces personnel who served in the Gulf War and Kosovo. Health Physics, 82 (4), 527–532.
• Randall, J.A. and Gibson, R.S. (1989). Hair chromium as an index of chromium exposure of tannery workers. British Journal of Industrial Medicine, 46(3), 171–175.
• Ratelle, M., Skinner, K., Laird, M.J., Majowicz, S., Brandow, D., Packull-McCormick, S., Bouchard, M., Dieme, D., Stark, K.D., Henao, J.J.A., et al. (2018). Implementation of human biomonitoring in the Dehcho region of the Northwest Territories, Canada (2016–2017). Archives of Public Health, 76(1).
• Ruggieri, F., Majorani, C., Domanico, F., Alimonti, A. (2017). Mercury in Children: Current State on Exposure through Human Biomonitoring Studies. International Journal of Environmental Research and Public Health, 14(5), 519.
• Spallholz, J.E., Boylan, L.M., Palace, V., Chen, J., Smith, L., Rahman, M.M. and Robertson, J.D. (2005). Arsenic and selenium in human hair: A comparison of five countries with and without arsenicosis. Biological Trace Element Research, 106 (2), 133–144.
• Vaghri, Z., Barr, S., Wong, H., Chapman, G. and Hertzman, C. (2008). Age-based differences in hair zinc of Vancouver preschoolers. Biological Trace Element Research, 126 (suppl. 1), S21–S30.
• Vanderkooy, P.D.S. and Gibson, R.S. (1987). Food consumption patterns of Canadian preschool children in relation to zinc and growth status. American Journal of Clinical Nutrition, 45, 609–616.
• UNEP/WHO (United Nations Environment Programme/World Health Organization) (2008). Guidance for Identifying Populations at Risk from Mercury Exposure. UNEP/WHO, Geneva. Retrieved February 25, 2019.

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