19085-1701857-UL_Prop_65_Test_Results_2019

Released by UL Environment
Date Prepared:
February 11, 2019
Report #:
1000339735-1162663EA
©2019 UL LLC
CA Prop 65 Exposure Assessment Page 5 | 15
Equation 1 estimates the 1,4 dioxane, acetaldehyde and cumene concentrations in specific
indoor environments based on measured emission rates (EF
A
), the emitting surface area
(A) that is within the indoor environment, and the clean, outdoor, ventilation airflow rate (Q).
From Equation 1, it is evident that a larger emitting surface area (A) will result in a higher
VOC concentration, while increased outdoor airflow (Q) will result in a lower VOC
concentration. This assessment uses “worst-case” conditions for both emitting surface
area and outdoor airflow rate to conservatively estimate indoor air 1,4 dioxane,
acetaldehyde and cumene concentrations associated with use of the Execumat Chair Mats
within either an occupational or residential environment.
VOC Emission Rates from the Execumat Chair Mats
The decrease in VOC emission rates from consumer products over time is an important
factor in reducing the indoor air concentrations of VOCs. This VOC emission decay has
been reported by several investigators in laboratory studies of wood products, carpet
products and thermoset composite materials (ATSDR, 2010; Crawford, 2011; Schaeffer,
1996; Hodgson, 1993 and 1999). For example, in one study, Crawford (2011) reported that
styrene concentrations emitted from newly manufactured thermoset composite material
decreased from 0.127 mg/m
3
to 0.014 mg/m
3
between 48 and 162 hours. Likewise, styrene
emissions from new carpet assemblies were reported to decrease rapidly over the initial
two to three days of chamber measurements (Hodgson, 1999).
Similar decreases in the 1,4 dioxane, acetaldehyde and cumene emissions have been
observed for the Execumat Chair Mats during environmental chamber tests (UL report #
1000333735-1162663, issued on 12/28/2017). Specifically, air chamber samples collected
over a 168-hour time course show 1,4 dioxane decrease from 4.9 µg/m
2
hr
-1
at the 6-hour
time point down to below the quantification limit (2 µg/m
2
hr
-1
) at the 168-hour time point.
Acetaldehyde emissions decrease from 6.9 µg/m
2
hr
-1
at the 6-hour time point down to 5.1
µg/m
2
hr
-1
at the 168-hour time point. Cumene emissions decrease from 15.2 µg/m
2
hr
-1
at
the 6-hour time point down to 5.5 µg/m
2
hr
-1
at the 168-hour time point.
To calculate an indoor 1,4 dioxane, acetaldehyde and cumene air concentration associated with
an emission source using Equation 1, a discrete emission rate must be selected. Therefore, it is
conservatively assumed herein that a consumer is exposed, over the product life, to the 95th
percentile emission rate based on a 25-year decay period. The 95th percentile emission rate is
calculated using the data measured for the Execumat Chair Mats during the 168-hour indoor air
chamber analysis. Specifically, a power equation was fit to the 1,4 dioxane, acetaldehyde and
cumene emissions measured during the decay portion of the time course using the curve fitting
function within MS Excel, Office 2016. The power curve equations were then used to predict
1,4 dioxane, acetaldehyde and cumene emission rates over a 25-year product life. The 95th
percentile emission rates of 0.69 µg/m
2
h
-1
, 3.6 µg/m
2
h
-1
and 1.8 µg/ m
2
h
-1
were calculated for
1,4 dioxane, acetaldehyde and cumene, respectively. These calculated emissions are used