Polymorphisms in genes encoding potential mercury transporters and urine mercury concentrations in populations exposed to mercury vapor from gold mining.
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.
Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden. karin.engstrom@med.lu.se
Karin
K
Engström
Shegufta
S
Ameer
Ludovic
L
Bernaudat
Gustav
G
Drasch
Jennifer
J
Baeuml
Staffan
S
Skerfving
Stephan
S
Bose-O'Reilly
Karin
K
Broberg
D000328:Adult; D005260:Female; D006046:Gold; D006801:Humans; D008297:Male; D008628:Mercury / Q000633:toxicity* / Q000652:urine*; D008875:Middle Aged; D008906:Mining; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics
D006046:Gold; D008628:Mercury; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C000715087:ABCC2 protein, human