Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:10:p7
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 10 (pt 7/11)
Character Range: 2252997–2256152

speciation is limited, the toxicological database on mercury (II) chloride was relevant for establishing a PTWI for foodborne inorganic mercury. A PTWI was established on the bases of a benchmark dose approach, where the BMDL10 of 0.06 mg/kg/day for relative kidney weight increases in male rates was considered as the point of departure. A 100 fold uncertainty factor was applied.
                    (equivalent to PTDI = 0.0006 mg/kg/day)
WHO (2000b)         TC = 0.001 mg/m3                                      TC or guideline value derived on the basis of a LOAEL derived from occupational studies on elemental vapour. WHO notes that this value is expected to be adequately protective of renal effects associated with exposure to inorganic mercury.
WHO (2003)          TDI = 0.002 mg/kg/day                                 TDI derived as noted in the DWG above.
                    TC = 0.0002 mg/m3                                     A TC in air was also derived for elemental mercury in air (0.0002 mg/m3) associated with CNS effects in workers exposed to elemental mercury. The relevance of this value to inorganic compounds is not discussed. The TC is considered relevant to inhalation exposures to elemental vapour.
EA (2009)           TDI = 0.002 mg/kg/day                                 TDI referenced from WHO (2003) and WHO DWG (2011). Inhalation value (converted to a dose by the EA) is based on the WHO (2003) value and has been assumed to be relevant to inorganic mercury in air.
                    TC = 0.0002 mg/m3
RIVM (2001)         TDI = 0.002 mg/kg/day                                 Derived on the same basis as WHO. No inhalation value is derived for inorganic mercury.
ATSDR (1999)        No chronic MRLs derived                               No chronic duration MRLs have been derived for inorganic mercury. An intermediate duration oral MRL of 0.002 mg/kg/day was derived.
US EPA (IRIS 2012)  RfD = 0.0003 mg/kg/day                                RfD (last reviewed in 1995) based on a LOAEL of 0.226 mg/kg/day associated with autoimmune effects in a subchronic rat feeding study and an uncertainty factor of 1000.
                                                                          No RfC is available for inorganic mercury. An RfC of 0.0003 mg/m3 is derived for elemental mercury.

The PTWI derived for inorganic mercury available from JECFA (WHO 2011a) is considered to provide the most current review of the available studies in relation to exposure to inorganic mercury and has been used in the derivation of a soil HIL.
Inhalation values for mercury are derived from occupational studies associated with elemental mercury vapour.  While WHO (2000b) provides some comment on the potential relevance of the guideline value derived to the assessment of inorganic mercury in air, the available toxicity data does not specifically relate to the inhalation of inorganic mercury compounds likely to be present in soil contamination. EA (2009) has adopted the lower guideline value (TC) available from WHO (2003) assuming its relevance to the assessment of inorganic mercury. This approach has been adopted, though it