Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 3/8)
Character Range: 2785507–2788517

Other significant exposures of the general public are likely to occur through the use of dry-cleaning. Variable concentrations of PCE in homes and where dry-cleaned clothes are stored and worn are reported by NICNAS (2001) and WHO (2000). A study on the effect of wearing dry-cleaned clothes reported median personal air concentrations ranging from 0.032 mg/m3 to 0.22 mg/m3, depending on the garment. These exposures, together with exposures to paint solvents and cleaning material containing PCE were considered potentially significant. No estimate of intake by the general public is provided in the NICNAS review. Median indoor air concentration reported by WHO (2006) for homes not located in the same building as dry-cleaners was 0.004 mg/m3 (note that concentrations indoors were much higher in buildings with a dry-cleaner with indoor air levels ranging from 0.05 to 6.1 mg/m3). This value is also essentially negligible compared with the recommended inhalation TRV. While there is the potential for increased background intakes depending on consumer use of products and frequency of dry-cleaning, average intakes are considered low, with a conservative average intake of 10% assumed in the derivation of HILs.

It is noted that other sources found indoors (from a wide range of common products) are likely to be present and may contribute more significantly to background exposures. These sources need to be addressed on a site-specific basis.

3.5              Identification of Toxicity Reference Values

    3.5.1         Classification
The International Agency for Research on Cancer (IARC 1995) has classified PCE as Group 2A—probably carcinogenic to humans, based on limited evidence in humans and sufficient evidence in experimental animals.

Review of PCE by US EPA (2012) classified it as 'Likely to be Carcinogenic to Humans' by all routes of exposure, based on suggestive evidence of carcinogenicity in epidemiologic studies and conclusive evidence that the administration of PCE, either by ingestion or by inhalation to sexually mature rats and mice, increases tumour incidence.

    3.5.2         Review of Available Values/Information
Some epidemiological studies indicate a possible association between chronic exposure to PCE and an increased cancer risk. Review of these studies has indicated that the evidence provided is inconclusive (US EPA 2012). This is mainly due to concurrent exposure to other petroleum solvents as well as PCE, confounding factors (smoking, alcohol, socio-economic status) and small numbers of cancers in the studies.

An association between exposure to PCE (inhalation and ingestion) and an increased risk of cancer (mononuclear cell leukaemia and hepatic tumours) in animals has been suggested. Review of PCE by WHO (2000) indicates that PCE is a non-genotoxic animal carcinogen. Review of the possible mechanisms of tumour formation by PCE in animals suggests that the tumours observed may have little relevance for humans. This is subject to some debate,