Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:10:p5
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 10 (pt 5/11)
Character Range: 2247478–2250380

the use of mercury dental amalgams is declining.
    * Based on the above, background intakes by young children may be up to 0.23 µg/kg/day from oral intakes (dietary, dental and water). This is slightly higher than intakes of 0.1 µg/kg/day from RIVM (2001) and 0.037 µg/kg/day from the UK (EA 2009, for 20kg child). These intakes comprise approximately 40% of the recommended oral TRV.
    * Levels of inorganic mercury in air are not available for Australia with estimates from WHO (2003) for mercury in air ranging from 1020 ng/m3 from the US (no indication on speciation between elemental and inorganic). These concentrations comprise up to 10% of the recommended inhalation TRV.
For methyl mercury, review of current information from Australia indicates the following:
    * Mercury levels are reported in the 20th Australian Total Diet Survey (FSANZ 2003). Dietary intakes of total mercury (which is dominated by organic mercury in seafood) ranged from 0.010.2 µg/kg/day for toddlers (aged 2 years). This is consistent with intakes reported in the more recent survey (FSANZ 2011).
    * The most recent review of methyl mercury by JECFA (WHO 2004) included a review of estimated dietary intakes from a number of countries. The review references previous total diet surveys (from 1992 and 1995) and indicates that the mean intake of methyl mercury for the population is approximately 0.7 µg/kg/week. It is noted that the 95th percentile intake estimated exceeds the recommended PTWI adopted by JECFA (WHO 2004). This is a conservative estimate but it suggests intakes may be a significant proportion of the recommended PTWI.
    * Reviews of background intakes of methyl mercury by EA (2009) and RIVM (2001) suggest intakes ranging from 820% of the adopted TDI (similar to the recommended TRV). Data from Australia suggests intakes may be higher and hence a value of 80% is recommended to address the potential for a significant proportion of the recommended oral TRV to be derived from background intakes.
It is noted that the potential for intakes in excess of the recommended oral TRV may occur in populations with high intakes of seafood. This may need to be considered on a site-specific basis.

10.4          Identification of Toxicity Reference Values

    10.4.1     Classification
The International Agency for Research on Cancer (IARC) has classified methyl mercury as Group 2B—possibly carcinogenic to humans. IARC has classified metallic mercury and inorganic mercury compounds as Group 3—not classifiable.

It is noted that US EPA has classified methyl mercury as Class C—possible human carcinogen. In addition, US EPA has classified mercuric chloride as Group C—possible human carcinogen, based on increased incidence of squamous cell papillomas of the forestomach and marginally increased incidence of thyroid follicular cell adenomas and carcinomas from long-term oral studies in