Exposure to asphalt or bitumen fume and renal disease.

Exposure to asphalt or bitumen fume and renal disease EDITOR,—The correspondence from Dittmer and Armitage 1 provides further support for a causal association between exposure to various hydrocarbons and the development of renal disease. Since 1912, some case reports, 2–4 case-control studies, 5 and cross sectional 6 studies together with animal experiments 7 8 have provided compelling evidence for a causative role for hydrocarbon exposure in the development of both tubular and glomerular lesions. We now report the case of a road worker exposed to asphalt and bitumen fumes who presented in 1990 at the age of 36 with neph-rotic syndrome. He was then normotensive, had proteinuria with 24 hour urinary protein of 12.2 g, showed some clinical oedema, and his renal biopsy was consistent with a diagnosis of stage 2 membranous glomerulonephritis. Later that year he presented with an unexplained deterioration in renal function. This followed several weeks of abdominal pain, and he then had haematuria without pyuria, serum creatinine of 298 compared with his previously normal value of 85 µmol/l, and a marked deterioration in his renal biopsy with 20 glomeru-lar profiles per section and tubulointerstitial scarring occupying 40% of the biopsy. Before developing renal disease, the patient had been employed as a road worker for more than 10 years, during which time he was repeatedly exposed to intermittent but high concentrations of asphalt or bitumen fumes. Since the diagnosis of nephrotic syndrome due to membranous glomerulonephritis, the patient stopped being exposed to asphalt and bitumen fumes. Subsequent assessments of proteinuria have shown a reduction of up to 50% from 12 to 5 g/day. However, he currently is hypertensive with serum creati-nine 170 µmol/l, urea 10.4 mmol/l, serum albumin 30 mmol/l, and 24 hour urinary excretion of protein 5.0 g. Searches of the scientific literature in 1990 and subsequently have not found any specific references to exposure to asphalt or bitumen and renal disease. We therefore investigated the issue further by means of (a) detailed fume analyses, and (b) a study of the renal health of road workers exposed to asphalt or bitumen. It was clear from the fume analyses that exposures in this industry include a wide range of aromatic and aliphatic hydrocarbons. Time weighted average exposures ranged from 0.4 to 8.9 mg/m 3 measured as total organic fume (not including inorganic particulates), but short term or peak fume exposures were as high as 300–900 mg/m 3. …