Regulation and Risk Assessment of 1,4-Dioxane - Environmental Investigation and Remediation - page 303

TABLE 6.21
Exposure Estimates for Dermal Exposure to 1,4-Dioxane from Sundries

1. Shampooing Scenario: Adult Dermal Exposure

Weight: 65 kg (143 lb) Duration: 10 min;

frequency: 2-7 per week

Volume: 2 cm 3 shampoo
(12 g)

Concentration: 50 mg 1,4-dioxane
per 1 kg shampoo (50 ppm)

Dilution: 10-fold Absorbed fraction: 100% Cumulative worst-case

exposure: 21.4 mg/year

Cumulative worst-case daily
exposure: 0.0009 mg/kg

2a. Infant Dermal Exposure Scenario for 1,4-Dioxane in Baby Lotion

Weight: 8 kg (~18 lb) Frequency: 1 application

per day

Volume: 2 cm 3 lotion (2.4 g) 1,4-Dioxane weight fraction:

0.00001 (10 ppm)

Concentration of
1,4-dioxane in lotion:
0.012 mg/cm 3

Absorbed fraction: 100% Cumulative worst-case

exposure (estimate):
8.8 mg/year

Cumulative worst-case daily
exposure (estimate):0.003 mg/kg

2b. Adult Dermal Exposure Scenario for 1,4-Dioxane in Baby Lotion

Weight: 65 kg (143 lb) Frequency: 1-2

applications per day

Volume: 7.5 cm 3 lotion
(7.5 g)

1,4-Dioxane weight fraction:
0.00001 (10 ppm)

Concentration of
1,4-dioxane in lotion:
0.01 mg/kg

Absorbed fraction: 100% Cumulative worst-case

uptake (estimate): 54 mg/
year

Daily cumulative worst-case
uptake (estimate): 0.00023 mg/kg

3. Adult Dermal Exposure Scenario for 1,4-Dioxane in Dish-Washing Liquid
Weight: 70 kg (154 lb) Duration: 40 min/day Volume: 2-10 cm 3 liquid

(2-10 g)

Concentration: 30 mg 1,4-dioxane
per 1 kg liquid (30 ppm)

Dilution: 2000-fold Absorbed fraction: 100% Cumulative worst-case

uptake (estimate):
0.053 mg/year

Daily cumulative worst-case
uptake (estimate): 2.08

× 10 -6

mg/kg

Margins of Safety: Calculated Exposures versus Daily Dermal NOAEL of 20 mg/kg

Cumulative Worst-Case
Daily Uptake (mg/kg)

Margin of Safety
Compared to NOAEL a Scenario

Adult shampooing 0.0009 22,222

Infant baby lotion 0.003 6666

Adult baby lotion 0.00023 89,000

Adult dish-washing soap 2.08 × 10 -6 >1,000,000

Sources: European Chemicals Bureau (ECB), 2002, European Union risk assessment report: 1,4-Dioxane. Institute for Health
and Consumer Protection, European Union; VROM, 1999, Risk assessment: 1,4-Dioxane . Bilthoven, Netherlands:
S. P. Netherlands Ministry of Housing and the Environment (VROM), Chemical Substances Bureau.
Note: The European Chemicals Bureau calculates a dermal NOAEL for 1,4-dioxane of 20 mg/(kg d); other risk assessors
note that a reliable NOAEL for chronic dermal effects has not been determined (NICNAS, 1998).

a

The margin of safety is obtained by dividing the European Chemicals Bureau value for the calculated 1,4-dioxane dermal
NOAEL (20 mg/(kg d)), by the calculated cumulative worst-case daily uptake.

840 cm 2 ), E is the exposure duration (i.e., 8 h/day), F is the skin contact time as a daily
percentage (i.e., 4.16%

only =

0.042 day or 1 h), and BW is the average body weight of worker (70 kg).
In summary, the dermal exposure route can be signii cant for unprotected occupational expo-
sure. The Netherlands risk assessment for 1,4-dioxane notes that repeated-dose toxicity and carci-
nogenicity from dermal exposure in the workplace cannot be ruled out for occupations using
cleaning agents that contain 1,4-dioxane (VROM, 1999). The relatively high NOAELs and the
absence of dose-response values for dermal exposure make it difi cult to estimate the health effects

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