Ga. Comp. R. & Regs. dept. 391, ch. 391-3, sub. 391-3-19, app (391-3-19) IV
U.S. EPA's Adult Lead Model provided in this appendix applies to the protection of industrial workers at nonresidential sites at which it can be demonstrated that children are not now exposed, nor will become exposed, to lead in soil or soil-derived dust at the site. U.S. EPA's ALM attempts to protect against elevated blood lead (PbB) levels in the unborn fetus of women who spend considerable time at the site. Protection of the PbB of a hypothetical fetus ensures that any other human receptor at the site will be adequately protected. The ALM ultimately involves two equations. Equation 1 establishes the average adult PbB level that is protective of the fetus, which is an input to Equation 2. Equation 2 calculates the target soil cleanup level for no more than 5% probability that fetal PbB exceeds the target PbB and the concentration that would generate the average adult PbB level indicated in Equation 1. |
EQUATION 1 PbB = PbBfetal,0.95 / R*GSD1.645 EQUATION 2 CS = [([[PbBfetal,0.95/(R*(GSDi1.645)] * PbBo) - (IRS*AFS)-1 / BKSF*(EF/AT) |
Exposure Variable | Description of Exposure Variable | Units | GSDi and PbBo from Analysis of NHANES 2007-2012 |
PbBfetal, 0.95 | 95th percentile PbB in fetus | µg/dL | 5 |
Rfetal/maternal | Fetal/maternal PbB ratio | -- | 0.9 |
BKSF | Biokinetic Slope Factor | µg/dL per µg/day | 0.4 |
GSDi | Geometric standard deviation PbB | -- | 1.8 |
PbBo | Baseline PbB | µg/dL | 0.6 |
IRS | Soil ingestion rate (including soil-derived indoor dust) | g/day | 0.05a |
AFS, D | Absorption fraction (same for soil and dust) | -- | 0.12 |
EFS, D | Exposure frequency (same for soil and dust) | days/year | 219a |
ATS, D | Averaging time (same for soil and dust) | days/year | 365 |
CS | Soil Lead Target Concentration where PbBt = 5 µg/dL | mg/kg | calculated |
a Any proposed site-specific value is subject to approval by the Division and should be protective of current and future exposure conditions at a site. |
Shaded cells - Based on U.S. EPA May 17, 2017 GSDi and PbB0 updated estimates (using data from NHANES 2009-2014) for the ALM and IEUBK. These values should be amended based on updates by the U.S. EPA Technical Review Workgroup for Lead - Adult Lead Committee. |
Ga. Comp. R. & Regs. R. dept. 391, ch. 391-3, sub. 391-3-19, app (391-3-19) IV