title: Hospital admissions for neurological and renal diseases among dentists and dental assistants occupationally exposed to mercury.
abstract: OBJECTIVE
  For many years an amalgam containing metallic mercury, which has been associated with neurological and renal diseases, has been used in dentistry. In this nationwide study we compared hospital admissions due to neurological and renal diseases among dentists and dental assistants to admissions in controls.
  
  
  METHODS
  This register-based cohort study included all Danish workers employed in dental clinics, general practitioners' clinics or lawyers' offices between 1964 and 2006. We compared dentists with general practitioners and lawyers, and dental assistants with medical secretaries, nurses and legal secretaries. We also compared dentists and dental assistants employed during periods with high occupational mercury exposure with dentists and dental assistants employed during periods with less mercury exposure. We followed all subjects in a nationwide register of hospital admissions. We analysed risk of neurological diseases, Parkinson's disease and renal diseases using a Cox regression model.
  
  
  RESULTS
  The cohort consisted of 122,481 workers including 5371 dentists and 33,858 dental assistants. For neurological diseases, no association was observed for dental assistants, while for dentists an increasing risk for periods with less mercury exposure was observed. Among dental assistants, a negative association between employment length and risk of neurological disease was observed. Admissions for renal disease among dental assistants were increased during periods with less mercury exposure compared with controls. For dentists a non-significant increased risk was observed between employment length and renal disease risk.
  
  
  CONCLUSIONS
  Our nationwide study does not indicate that occupational exposure to mercury increases the risk of hospital admissions for neurological, Parkinson's or renal diseases.
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5 A, 2nd floor, DK-1353 Copenhagen K, Denmark. lct@niph.dk
authors.forename: Lau Caspar
authors.initials: LC
authors.lastname: Thygesen
authors.forename: Esben Meulengracht
authors.initials: EM
authors.lastname: Flachs
authors.forename: Kirsten
authors.initials: K
authors.lastname: Hanehøj
authors.forename: Helge
authors.initials: H
authors.lastname: Kjuus
authors.forename: Knud
authors.initials: K
authors.lastname: Juel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003718:Denmark / Q000453:epidemiology; D003723:Dental Amalgam / Q000633:toxicity*; D003726:Dental Assistants / Q000706:statistics & numerical data; D003815:Dentists / Q000706:statistics & numerical data; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced / Q000453:epidemiology*; D008297:Male; D008628:Mercury / Q000633:toxicity* / Q000652:urine; D008875:Middle Aged; D009422:Nervous System Diseases / Q000139:chemically induced / Q000453:epidemiology*; D009784:Occupational Diseases / Q000139:chemically induced / Q000453:epidemiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D010302:Parkinson Disease, Secondary / Q000139:chemically induced / Q000453:epidemiology; D055815:Young Adult
chemical_list: D003723:Dental Amalgam; D008628:Mercury