Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:8:p6
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 8 (pt 6/8)
Character Range: 2212818–2215606

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 an increase in systolic blood pressure of approximately 3 mm Hg in adults. Both these effects were considered important within a population. The committee did not provide any indication of a suitable threshold for the key adverse effects of lead and no alternate PTWI was established.
WHO (2011)          No value provided             WHO has adopted a provisional guideline of 0.01 mg/L based on treatment performance and analytical achievability. The WHO evaluation notes the withdrawal of the JECFA PTWI (WHO 1993) and that no new value is available. The review notes that there does not appear to be a threshold for the key effects of lead.
WHO (2000)          TC = 0.5 µg/m3                Air guideline (based on an annual average) established for lead, based on an objective of 98% of the general population having a blood lead concentration of <10 µg/dL, where the median blood lead levels would be no more than 5.4 µg/dL.
RIVM (2001)         PTWI = 0.025 mg/kg            Adopted the JECFA (WHO 1993) evaluation.
DEFRA & EA (2002)   PbB goal <10 µg/dL            Guideline established for adults and children associated with exposures from all routes and sources. It is considered that neurotoxicity effects associated with lead exposure have no threshold and therefore an additional requirement to keep exposures from all sources as low as practically possible is noted.
ATSDR (2007)        No MRLs derived               No MRLs derived as some health effects associated with exposure to lead occur at blood lead levels as low as to be essentially without a threshold.
US EPA (IRIS 2012)  No RfD derived                No threshold values derived by the US EPA as it is noted that 'It appears that some of these effects, particularly changes in the levels of certain blood enzymes and in aspects of children's neurobehavioral development, may occur at blood lead levels so low as to be essentially without a threshold'.

The available goals reflect a blood lead goal of <10 µg/dL from all sources, which is considered relevant for all exposures and sources.

8.5              Calculated HILs
The HILs for lead have been previously established using both the JECFA (WHO 1993) PTWI and the blood lead model. Given that the PTWI has now been withdrawn and is no longer considered adequately protective, the HIL has been established on the basis of the blood lead model, on the basis of the blood lead goal of <10 µg/dL for all routes of exposure and all sources.

The most commonly used (and recommended) blood lead model relevant to the