Polymorphisms in Genes Encoding Potential Mercury Transporters and Urine Mercury Concentrations in Populations Exposed to Mercury Vapor from Gold Mining

Karin Engström,¹ Shegufta Ameer,¹ Ludovic Bernaudat,² Gustav Drasch,³ Jennifer Baeuml,⁴ Staffan Skerfving,¹ Stephan Bose-O’Reilly,^4,5 and Karin Broberg¹

¹Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden; ²United Nations Industrial Development Organization, Vienna, Austria; ³Institute of Forensic Medicine, Ludwig Maximilians University, Munich, Germany; ⁴Institute of Public Health, Medical Decision Making and Health Technology Assessment, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall in Tirol, Austria; ⁵Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, University Hospital Munich, Munich, Germany


Abstract

Background: Elemental mercury (Hg⁰) is widely used in small-scale gold mining. Persons working or living in mining areas have high urinary concentrations of Hg (U-Hg). Differences in genes encoding potential Hg-transporters may affect uptake and elimination of Hg.


Objective: We aimed to identify single nucleotide polymorphisms (SNPs) in Hg-transporter genes that modify U-Hg.


Methods: Men and women (1,017) from Indonesia, the Philippines, Tanzania, and Zimbabwe were classified either as controls (no Hg exposure from gold mining) or as having low (living in a gold-mining area) or high exposure (working as gold miners). U-Hg was analyzed by cold-vapor atomic absorption spectrometry. Eighteen SNPs in eight Hg-transporter genes were analyzed.


Results: U-Hg concentrations were higher among ABCC2/MRP2 rs1885301 A–allele carriers than among GG homozygotes in all populations, though differences were not statistically significant in most cases. MRP2 SNPs showed particularly strong associations with U-Hg in the subgroup with highest exposure (miners in Zimbabwe), whereas rs1885301 A–allele carriers had higher U-Hg than GG homozygotes [geometric mean (GM): 36.4 µg/g creatinine vs. 21.9; p = 0.027], rs2273697 GG homozygotes had higher U-Hg than A–allele carriers (GM: 37.4 vs. 16.7; p = 0.001), and rs717620 A–allele carriers had higher U-Hg than GG homozygotes (GM: 83 vs. 28; p = 0.084). The SLC7A5/LAT1 rs33916661 GG genotype was associated with higher U-Hg in all populations (statistically significant for all Tanzanians combined). SNPs in SLC22A6/OAT1 (rs4149170) and SLC22A8/OAT3 (rs4149182) were associated with U-Hg mainly in the Tanzanian study groups.


Conclusions: SNPs in putative Hg-transporter genes may influence U-Hg concentrations.


Key words: gold mining, inorganic mercury, LAT1, MDR1, MRP1, OAT1, OAT3, SLC3A2, SLC22A6, SLC22A8. 


Environ Health Perspect 121:85–91 (2013). http://dx.doi.org/10.1289/ehp.1204951 [Online 9 October 2012]


Address correspondence to K. Engström, Occupational and Environmental Medicine, Lund University Hospital, SE-22185 Lund, Sweden. Telephone: 46 (0) 46 173135. Fax: 46 (0) 46 143702. E-mail: karin.engstrom@med.lu.se


Supplemental Material is available online (http://dx.doi.org/10.1289/ehp.1204951).


The samples used in this study were derived from the Global Mercury Project (GMP) implemented by the United Nations Industrial Organization (UNIDO). We thank K. Paulsson for help with the genetic analyses. 


The study was supported by the Swedish Council for Working Life and Social Research, the Medical Faculty of Lund University, the County Councils of Southern Sweden, and the European Union (EU; FP6; PHIME; FOOD-CT-2006-016253).


The work reflects only the authors’ views; the EU is not liable for any use that may be made of the information. 


The authors declare they have no actual or potential competing financial interests.


Received 11 January 2012; Accepted 9 October 2012; Online 9 October 2012.