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Laura D. K. Thomas,¹ Susan Hodgson,² Mark Nieuwenhuijsen,^1,3 and Lars Jarup¹

¹Small Area Health Statistics Unit, Imperial College London, London, United Kingdom; ²Institute of Health and Society, Newcastle University, Newcastle, United Kingdom; ³Centre for Research in Environmental Epidemiology, Institut Municipal d'Investigació Mèdica, Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública, Barcelona, Spain

Abstract
Background: Exposure to heavy metals may cause kidney damage. The population living near the Avonmouth zinc smelter has been exposed to cadmium and other heavy metals for many decades.

Objectives: We aimed to assess Cd body burden and early signs of kidney damage in the Avonmouth population.

Methods: We used dispersion modeling to assess exposure to Cd. We analyzed urine samples from the local population (n = 180) for Cd (U-Cd) to assess dose (body burden) and for three biomarkers of early kidney damage [N-acetyl-β-d-glucosaminidase (U-NAG) , retinol-binding protein, and α-1-microglobulin]. We collected information on occupation, intake of homegrown vegetables, smoking, and medical history by questionnaire.

Results: Median U-Cd concentrations were 0.22 nmol/mmol creatinine (nonsmoking 0.18/smoking 0.40) and 0.34 nmol/mmol creatinine (nonsmoking 0.31/smoking 0.46) in non-occupationally exposed men and women, respectively. There was a significant dose–response relationship between U-Cd and the prevalence of early renal damage—defined as U-NAG > 0.22 IU/mmol—with odds ratios of 2.64 [95% confidence interval (95% CI) , 0.70–9.97] and 3.64 (95% CI, 0.98–13.5) for U-Cd levels of 0.3 to < 0.5 and levels ≥ 0.5 nmol/mmol creatinine, respectively (p for trend = 0.045) .

Conclusion: U-Cd concentrations were close to levels where kidney and bone effects have been found in other populations. The dose–response relationship between U-Cd levels and prevalence of U-NAG above the reference value support the need for measures to reduce environmental Cd exposure.

Key words: cadmium, environmental exposure, heavy metals, kidney disease, nephrotoxicants, zinc smelter. Environ Health Perspect 117:181–184 (2009) . doi:10.1289/ehp.11641 available via http://dx.doi.org/ [Online 9 September 2008]

Address correspondence to L. Jarup, SAHSU, Department of Epidemiology and Public Health, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK. Telephone: 0044-0-20-7594-3337. Fax: 0044-0-20-7594-3196. E-mail: l.jarup@imperial.ac.uk

We thank Bristol Primary Care Trust and the Health Protection Agency for collaborating on this project and the British Atmospheric Data Centre for supplying data. We especially thank all study participants in Avonmouth.

The work of the Small Area Health Statistics Unit is funded by a grant from the Department of Health for England and the U.K. Department for Environment, Food, and Rural Affairs. Additional funding for and advice on this study was provided by the Environment Agency.

The authors declare they have no competing financial interests.

Received 29 April 2008 ; accepted 9 September 2008.