Table 13.

Estimated HD and VX Degradation Product Surface Removal Contaminant Levels (SRCLs) for child transit passengers.^a

CWA Degradation Product	Transit Passenger SRCL4bc Protective estimate (mg/cm2 surface, continuous exposure)	Transit Passenger SRCL24bd Protective estimate (mg/cm2 surface, continuous exposure)
TDG (thiodiglycol)	1.06 × 102	1.77 × 101
EMPA (ethyl methylphosphonic acid)	7.08	1.18
MPA (methyl phosphonic acid)	5.06	8.44 × 10−1
EA2192	1.89 × 10−3	3.15 × 10−4

^aChemical formulae: TDG, C₄H₁₀O₂S; EMPA, C₃H₉O₃P; MPA, CH₅O₃P; EA2192, C₉H₂₂NO₂PS.

^bThe “child passenger” estimate employs child-specific information regarding object mouthing behavior and dermal contact with surfaces, and is thus a protective estimate for adult transit passengers. Passenger SRCL estimates incorporate contaminant transfer from hard and soft surfaces to the eye, skin, and mouth (incidental ingestion), as well as potential particle inhalation due to resuspension from surfaces.

^cSRCL4 assumes average exposure dwell time of 4 continuous h (incorporates inhalation toxicity value for exposure durations ≤8 h).

^dSRCL₂₄ assumes maximal exposure dwell time of 24 continuous h (incorporates inhalation toxicity value for exposure durations >8 h but ≤24 h).