Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:8:p5
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 8 (pt 5/8)
Character Range: 2210268–2213060

to also be adequately protective of carcinogenic effects.

Blood lead levels have been found to be a good indicator of exposure to lead. A blood lead level reflects lead's dynamic equilibrium between adsorption, excretion and deposition in soft and hard tissues. Epidemiological studies (and expert groups) do not provide definitive evidence of a threshold in relation to blood lead levels and neurotoxic effects (US EPA (IRIS 2012), ATSDR 2007, DEFRA & EA 2002 and RIVM 2001) but blood lead goals and associated intakes have been identified by various agencies for the assessment of lead exposures by the general public.  The NHMRC has noted that there are no benefits of human exposure to lead and that all demonstrated effects of exposure are adverse.

The following threshold values are available from Level 1 Australian and International sources:
Source              Value                         Basis/Comments
Australian
ADWG (NHMRC 2011)   PTDI = 0.0035 mg/kg/day       The PTDI considered in the ADWG (NHMRC 2011) is based on the evaluation provided by JECFA (WHO 1993 and WHO 2011) associated with a PTWI of 0.025 mg/kg/week (see comments below).
NHMRC (2009)        PbB goal <10 µg/dL            Blood lead goal set in 1987 and re-iterated in 1993. The document provides a series of graduated response levels associated with concentrations ranging from 1525 µg/dL. The guidance was rescinded by the NHMRC on 31/12/2005. NHMRC (2009) notes that the value of 10 µg/dL was never intended as a 'safe' level of exposure of a 'level of concern', however they still recommend that goal of <10 µg/dL for all Australians.
NEPM (2003)         Air Quality Goal = 0.5 µg/m3  Air guideline (based on an annual average) set by NEPM. Basis of the value is not stated; however it is the same as that set by WHO (2000).
International
JECFA (WHO 1993)    PTWI = 0.025 mg/kg            In 1972 the JECFA set a PTWI of 0.05 mg/kg. The current PTWI was established in 1986 for infants and children based on metabolic studies showing a mean daily intake of 34 µg/kg was not associated with an increase in blood lead levels or in the body burden of lead. An intake of 5 µg/kg was associated with an increase in lead retention. The PTWI was reconfirmed in 1993 and extended to all age groups. The PTWI was estimated to be responsible for a blood lead concentration of 5.6 µg/dL for a 10 kg child, which is thought to be below that associated with effects on intellectual performance.
                                                  This PTWI was withdrawn by JECFA in 2010 (WHO 2010) as the committee could no longer consider the value to be health-protective. The committee estimated that the previous PTWI is associated with a decrease of at least 3 intelligence quotient (IQ) points in children and