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Urinary concentrations of toxic substances: an assessment of alternative approaches to adjusting for specific gravity

  • Tom Sorahan
    ,
  • Dong Pang
    ,
  • Nurtan Esmen
    ,
  • Steven Sadhra
  • University of Birmingham
    ,
  • The Royal Manchester Children's Hospital
    ,
  • University of Illinois at Chicago
Research Output:
Contribution to journal
Article
 Peer-review

Abstract

Alternative approaches of adjusting urinary concentration of cadmium for differences in specific gravity of biological samples were assessed. The main analysis used 2922 cadmium-in-urine samples collected in the period 1968–1989 from workers at a UK nickel-cadmium battery facility. Geometric means of cadmium-in-urine, adjusted and unadjusted for specific gravity, were obtained for 21 different values of specific gravity ranging from 1.010 to 1.030. There was a highly significant positive trend (P < 0.001) of unadjusted cadmium-in-urine with specific gravity. Conventional adjustment for specific gravity led to a highly significant negative trend (P < 0.001) of adjusted cadmium-in-urine with specific gravity, SG. An approach proposed by Vij and Howell, involving the introduction of a z coefficient, led to satisfactory adjustment. Conventional adjustment of specific gravity leads to overcompensation of the confounding effects of specific gravity. An alternative method is available and should probably be adopted when interpreting urine biological samples for all chemical substances.

Publication Information

Output type

Research Output:
Contribution to journal
Article
 Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 721-723

Journal (Volume, Issue Number)

Journal of Occupational and Environmental Hygiene (Volume 5, Issue 11)

Publication milestones

  • Published - 01/11/2008

Publication status

Published - 01/11/2008

ISSN

1545-9624

Publication IDs

  • handle.net: 10547/227171
  • Scopus: 55949119067

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