Environmental lab report distribution, May 2002

NYC 9/11 Public Portal Document

exposure (i.e., 1 year), acute effects from exposures that are below the benchmark levels would be unlikely. Additionally, a review of California EPA’s (CAL-EPA) Acute Risk Levels demonstrates that the benchmark levels developed are categorically more stringent than the Cal-EPA’s analogous acute levels.

Developing Risk-Based Criteria for Dust

Wipe sampling is a common technique used to estimate the amount of exposure that occurs from contact with contaminated surfaces. There is no established national guidance, and very little scientific literature, for the estimation of risks from wipe samples. The EPA approach used in this report was developed by the EPA Superfund program, and is consistent with evaluations found in literature. The approach involves analyzing the wipe sample for the concentration of the contaminant on the indoor surface, estimating the exposure to that contaminant concentration to determine dose in the body, and using this information to estimate risk.

Exposure to a contaminant on an indoor surface is estimated by calculating 1) the amount of the contaminant that is deposited on the skin touching the surface, 2) the fraction that is then transferred from the skin to the mouth, and 3) the fraction that is absorbed by the skin into the body. The three equations are as follows [Radian International 1999]:

1) Ds = C X SA X CF X FTSS x EF x ED

Ds = Amount of chemical deposited on skin (mg) C = Concentration of chemical on contaminated surface (mg/cm2) SA = Exposed skin surface area (cm2) CF = Contact frequency of skin against surface (1/day) FTSS = Fraction transferred from surface to skin EF = Exposure frequency (days/year) ED = Exposure duration (years)

2) Do = (Ds X FTSM x ABSo)/(BW x AT)

Do = Oral dose (mg/kg/day) FTSM = Fraction transferred from skin to mouth ABSo = Oral absorption fraction BW= Body weight (kilograms) AT = Averaging time (days)

3) Dd = (Ds X (1-FTSM) x ABSd)/(BW x AT)

Dd = Dermal dose (mg/kg/day) FTSM = Fraction transferred from skin to mouth ABSd = Dermal absorption fraction

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