title: Low-level methylmercury exposure through rice ingestion in a cohort of pregnant mothers in rural China.
abstract: Rice ingestion is an important dietary exposure pathway for methylmercury. There are few studies concerning prenatal methylmercury exposure through rice ingestion, yet the health risks are greatest to the developing fetus, and thus should be investigated.
  
  
  
  Our main objective was to quantify dietary methylmercury intake through rice and fish/shellfish ingestion among pregnant mothers living in southern China, where rice was a staple food and mercury contamination was considered minimal.
  
  
  
  A total of 398 mothers were recruited at parturition, who donated scalp hair and blood samples. Total mercury and/or methylmercury concentrations were measured in biomarkers, in rice samples from each participant's home, and in fish tissue purchased from local markets. Additional fish/shellfish mercury concentrations were obtained from a literature search. Dietary methylmercury intake during the third trimester was equivalent to the ingestion rate for rice (or fish/shellfish)×the respective methylmercury concentration.
  
  
  
  Dietary methylmercury intake from both rice and fish/shellfish ingestion averaged 1.2±1.8µg/day (median=0.79µg/day, range=0-22µg/day), including on average 71% from rice ingestion (median: 87%, range: 0-100%), and 29% from fish/shellfish consumption (median 13%, range: 0-100%). Median concentrations of hair total mercury, hair methylmercury, and blood total mercury were 0.40µg/g (range: 0.08-1.7µg/g), 0.28µg/g (range: 0.01-1.4µg/g), and 1.2µg/L (range: 0.29-8.6µg/L), respectively, and all three biomarkers were positively correlated with dietary methylmercury intake through rice ingestion (Spearman's rho=0.18-0.21, p≤0.0005), although the correlations were weak. In contrast, biomarkers were not correlated with fish/shellfish methylmercury intake (Spearman's rho=0.04-0.08, p=0.11-0.46).
  
  
  
  Among pregnant mothers living in rural inland China, rice ingestion contributed to prenatal methylmercury exposure, more so than fish/shellfish ingestion.
authors.affiliation: Department of Environmental Health Sciences, University of South Carolina, Columbia, SC, USA.
authors.forename: Chuan
authors.initials: C
authors.lastname: Hong
authors.affiliation: MOE-Shanghai Key Lab of Children's Environmental Health, XinHua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: xdyu1108@163.com.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA.
authors.forename: Jihong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Public Health, Xi'an Jiaotong University College of Medicine, Xi'an, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Environmental Health Sciences, University of South Carolina, Columbia, SC, USA. Electronic address: rothenbs@mailbox.sc.edu.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Rothenberg
mesh_terms: D000328:Adult; D000818:Animals; D002681:China; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis* / Q000097:blood; D005260:Female; D005399:Fishes; D005506:Food Contamination / Q000032:analysis*; D006197:Hair / Q000737:chemistry; D006801:Humans; D018811:Maternal Exposure; D008628:Mercury / Q000032:analysis* / Q000097:blood; D008767:Methylmercury Compounds / Q000032:analysis* / Q000097:blood; D009035:Mothers; D012275:Oryza; D011247:Pregnancy / Q000097:blood; D012424:Rural Population; D012758:Shellfish; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D008628:Mercury
keywords: China; Fish; Mercury; Prenatal exposure; Rice