albuminuria, are discussed briefly. The draft IRIS assessment notes that the results are contradictory. It should also note that some albumin is normally filtered, so small increases in the amount of albumin in the urine can be indicative of tubular damage (the result of failure to reabsorb the small amount filtered). EPA’s table should also include the negative findings on albumin in studies by Verplanke et al. (1999) and Lauwerys et al. (1983) and on total protein by Vyskocil et al. (1990). EPA concluded that the epidemiologic studies provided evidence suggestive of subtle damage in renal tubules. The committee agrees with that assessment.
Several types of epidemiologic studies have been used to explore a possible association between jobs in which workers are exposed to tetrachloroethylene and renal-cell carcinoma (RCC), including cohort mortality studies, case-control studies, and nested case-control studies. Ultimately, the methodologic challenges of studying such a rare cancer as RCC, assessing tetrachloroethylene exposure accurately, and evaluating inconsistencies in results among studies limit the conclusions that can be drawn from the epidemiologic data. Most of the studies either did not have explicit information about exposures or had considerable methodologic limitations.
Pesch et al. (2000) conducted a population-based case-control study in Germany that estimated tetrachloroethylene exposure with a job-exposure matrix (JEM) and a job-task exposure matrix (JTEM). The latter is usually superior for estimating specific exposures. The data were acquired in in-person interviews, so information on occupational history was obtained and confounding covariates (such as smoking) were well measured. An increased odds ratio (OR) for tetrachloroethylene exposure was observed in men who had a medium exposure index (OR, 1.4; 95% confidence interval [CI], 1.1-1.7) or a substantial exposure index (OR, 1.4; 95% CI, 1.1-2.0) on the basis of the JEM. However, the results based on the JTEM were less convincing (OR, 1.2; 95% CI, 0.9-1.7 and OR, 1.3; 95% CI, 0.7-2.3 for medium and substantial exposure, respectively). In contrast, no association was observed in women on the basis of the JEM, but a positive albeit imprecise association was observed on the basis of the JTEM for medium and substantial exposure (OR, 2.2; 95% CI, 0.9-5.2 and OR, 2.0; 95% CI, 0.5-7.8, respectively). Those variable results are representative of inconsistencies among studies. Lynge et al. (2006) (listed in Table 4B-4 of the EPA draft but not discussed in the renal-cancer section) conducted a nested case-control study in four Scandinavian countries in a cohort of about 47,000 persons employed in the laundry and dry-cleaning industry as of 1970 and followed through 1997-2001 to identify incident cancers. Multiple cancers were assessed, including 56 RCC cases in men and 154 in women. The cohort was divided into those who were not exposed to the dry-cleaning process, dry-cleaners and other exposed workers, and others working in dry-cleaning. Risk was also estimated by