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State of the Science Report for Dichloroethene
APPENDIX A: Upper-Bounding Estimates of Exposure to 1,1-Dichloroethene from Consumer Products 1
| Consumer product type |
Scenarios |
Estimated daily exposure |
Carpet latex backing |
Inhalation
The background for the following scenarios is detailed in the VCCEP submission on DCE (U.S. EPA, 2002b).
- maximum concentration of 3 ppm (3 µg/g) residual DCE monomer in carpet latex, with no loss during manufacturing and storage
- carpet is made using 20 oz. of wet latex per square yard of carpet
- a typical 20-m3 room has a ceiling 2.44 m high
| Average amount |
= |
(3 µg/g) (20 oz./yd.2) (28.35 g/oz.)
(0.83612 m2/yd.2) |
| = |
2034 µ g/m2 |
|
|
Scenario 1
- air exchanges per hour (k2) = 0.3
- release is first order and the rate constant (k1) is very large compared with k2
- complete release of residual DCE over the 5-year lifetime of the carpet (t = 5 years × 365.25 days/year × 24 h/day = 43 830 h)
| Average air concn. |
= |
(2034 µg/m2) (1-exp(-k2t)
k2t (2.44 m) |
For an average Canadian child 0.5-4 years old, with a breathing rate of 0.39 m3/h (EHD, 1998):
| Intake |
= |
(0.0634 µ g/m3) (0.39 m3/h) (24 h)
15.5 kg |
|
Scenario 1
Average air concentration = 0.0634 µg/m3
Daily intake = 0.038 µg/kg-bw per day |
| |
Scenario 2
- emission of DCE from carpet decreases as first-order decay, with the highest concentration being released initially. Over time, the amount available for release is reduced. It is assumed that the release rate constant corresponds to release half-lives of 2 weeks, 1 year and 5 years.
- first-order rate constant (k1) = ln 2/half-life
- air exchanges per hour (k2) = 0.3
- t = 5 × 365.25 × 24 = 43 830 h
| Air concn. |
= |
(k1)(2034 µg/m2)[1/k1(1-exp(-k1t)
- 1/k2(1-exp(-k2t)]
(k2-k1)t (2.44 m) |
For an average Canadian child 0.5-4 years old, with a breathing rate of 0.39 m3/h (EHD, 1998):
| Intake |
= |
(air concn. µg /m3) ( 0.39 m3/h ) (24 h)
(15.5 kg) |
|
Scenario 2
Air concentration (half-life) =
0.0633 µg/m3 (2 weeks)
0.061 µg/m3 (1 year)
0.032 µg/m3 (5 years)
Daily intake (half-life) =
0.04 µ g/kg-bw per day (2 weeks)
0.04 µ g/kg-bw per day (1 year)
0.02 µ g/kg-bw per day (5 years) |
Food in contact with PVDC film wrap |
Ingestion
- mean residual DCE monomer in film wrap migrating to food is 5 ng/g food (U.S. EPA, 2002b)
- mean food consumption for a 15.5-kg average Canadian child (0.5-4 years) is 1.8 kg/day (EHD, 1998)
- consumption factor (fraction of food in contact with packaging) for PVDC is 0.05 (U.S. FDA, 2002).
| Intake |
= |
(0.05) (5 ng/g) (1 µ g/1000 ng) (1.8 kg/day) (1000 g/kg)
(15.5 kg) |
|
Daily intake = 0.03 µ g/kg-bw per day |
- Each scenario assumes the maximum exposure possible for a 15.5-kg child (0.5-4 years), as this group has the highest inhalation volume and food consumption relative to body weight.
