The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Toxicological Risks of Selected Flame-Retardant Chemicals
(0.25/hr) and with a relatively large amount of fabric upholstery treated with antimony trioxide (30 m2 in a 30-m3 room), with this treatment gradually being worn away over 25% of its surface to 50% of its initial quantity over the 15-yr lifetime of the fabric. A small fraction, 1%, of the worn-off antimony trioxide is released into the indoor air as inhalable particles and is breathed by the occupant. Equations 4 through 6 in Chapter 3 were used to estimate the average concentration of antimony trioxide in the air. The highest expected application rate for antimony trioxide is 2.5 mg/cm2. The estimated release rate is 2.3× 10−7/d. Using those values, the estimated time-averaged exposure concentration for antimony trioxide is 0.24 µg/m3.
Division of that exposure concentration (0.24 µg/m3) by the inhalation RfC (2×10−4 mg/m3; see Quantitative Toxicity Assessment section) results in a hazard index of 1.2, indicating that under the worst-case exposure scenario, antimony trioxide might possibly pose a noncancer risk via inhalation of particles.
Vapors
In addition to the possibility of release of antimony trioxide in particles worn from upholstery fabric, the subcommittee considered the possibility of its release by evaporation. However, because of antimony trioxide’s negligible vapor pressure at ambient temperatures, the subcommittee considered antimony trioxide not likely to pose a noncancer risk by exposure to vapors.
Oral Exposure
The assessment of the noncancer risk by the oral exposure route is based on the scenario described in Chapter 3. That exposure assumes that a child sucks on 50 cm2 of fabric backcoated with antimony trioxide daily for two yr, one hr/d. The highest expected application rate (per unit time) for antimony trioxide is about 2.5 mg/cm2. The fractional release rate of antimory trioxide is estimated as 0.001/d, based on the leaching of antimony from polyvinyl chloride cot mattresses (Jenkins et al. 1998). Using those assumptions and Equation 15 in Chapter 3, the average oral dose rate is estimated to be 0.00052 mg/kg-d. Division of that exposure estimate (0.00052 mg/kg-d) by the oral RfD (0.2 mg/kg-d; see Quantitative Toxicity Assessment section) results in a hazard index of 2.6×10−3. Therefore, under the worst-case exposure assumptions, antimony trioxide, used as a flame retardant in upholstery fabric, is not likely to pose a noncancer risk by the oral route of exposure.
Items in cart [0]
