Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 9/16)
Character Range: 2073974–2076903

in the APVMA (2005) review. The review considered that skin cancers appear to be the most sensitive indicator of carcinogenicity of inorganic arsenic in humans and, based on epidemiological studies, a threshold of 2.9 μg/kg/day (rounded to 3 μg/kg/day) can be obtained. This threshold is the value adopted as a provisional tolerable daily intake (PTDI) by FSANZ (FSANZ 2003), similar to the former PTWI available from WHO (noted above). This approach has been considered by APVMA for all intakes of arsenic (oral, dermal and inhalation). The evaluation has not been further updated.

1.4.3.2         Oral DoseResponse Approaches - International
Evaluation of arsenic by JECFA (WHO 2011a) considered the available epidemiological data in relation to the increased incidence of lung cancer and urinary tract cancer associated with exposure to arsenic in water and food. Using the data associated with these end points, JECFA derived a benchmark dose lower confidence limit for a 0.5% increased incidence (BMDL0.5) of lung cancer (most sensitive  end point) of 3 μg/kg/day (ranging from 27 μg/kg/day). Uncertainties associated with the assumptions associated with total exposure, extrapolation of the BMDL0.5 and influences of the existing health status of the population were identified. Given the uncertainties and that the BMDL0.5 was essentially equal to the PTWI (WHO 1989), the PTWI was withdrawn. No alternative threshold values were suggested by JECFA, as the application of the BMDL needs to be addressed on a regulatory level, including when establishing guideline levels.

The review conducted by JECFA is generally consistent with that conducted by the European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain (CONTAM) (EFSA 2010). The review concluded that the PTWI was 'no longer appropriate as data is available that shows inorganic arsenic causes cancer of the lung and bladder in addition to skin, and that the range of adverse effects had been reported at exposures lower than those reviewed by the JECFA' in establishing the PTWI. Modelling conducted by EFSA considered the available epidemiological studies and selected a benchmark response (lower limits) of 1% extra risk (BMDL01). BMDL01 range from 0.38 μg/kg/day for cancers of the lung, bladder and skin. The CONTAM Panel (EFSA 2010) concluded that the overall range of BMDL01 values of 0.38 μg/kg/day should be used for the risk characterisation of inorganic arsenic rather than a single reference point, primarily due to the number of uncertainties associated with the possible doseresponse relationships considered. On this basis it would not be appropriate to consider just one value in the range presented.

The derivation of a soil HIL requires the identification of an appropriate TRV, rather than a wide range of values, that is considered adequately protective of the population potentially exposed. The determination of an