LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
2) Environmental monitoring data were collected via two comprehensive US studies. The first determined
LAS surface water and sediment concentrations over 3 separate research vessel cruises on the 2800
kilometer reach of the Mississippi River between Minneapolis and New Orleans in three seasons of 1991-
92. The second determined concentrations of LAS in wastewater plants and surface waters, at 50 locations
in 11 states. These data are summarized in Format B attachments.
3) Potential LAS exposures estimated via modeling are summarized in Format C attachments. Potential
exposures resulting from manufacturing facility effluent discharges are modeled using US EPA’s E-FAST
model. This modeling includes estimates of aquatic exposure based on modeled surface water
concentrations. Potential human exposure is estimated based on modeled drinking water concentrations
and fish consumption from sources downstream from effluent discharges. Similarly, potential aquatic
exposures and human exposures from drinking water and fish consumption are modeled using E-FAST
following consumer use of products containing LAS (i.e., down-the-drain releases). Finally, dermal
exposures from consumer uses of products are examined using general exposure models for three exposure
scenarios: 1) use of diluted and undiluted laundry and cleaning products (laundry pre-treatment, handwash
of laundry, hand-wash of dishes, washing of hands with dishwashing liquid) and diluted and
undiluted hard surface cleaning products; 2) exposure to laundry and fabric conditioning product residual
on clothing (liquid, dry and tablet laundry detergents, dryer sheet fabric conditioner); and 3) exposure to
face and hand soap residual after use.
(3) Discussion of Key Uncertainties, Limitations, Data Gaps
a) Manufacturers representing about 75% of the US volume were involved in the industry survey. Thus, it
is possible that there may be minor uses and potential consumer exposures beyond those estimated here.
However two recently published economic reviews and a published European assessment support the uses
presented. In the assessment, the estimated volume encompassing all US producers was used and
exposure estimates are presented for all known uses.
b) This exposure assessment takes a conservative (protective) approach to modeling, selecting inputs
based on conservative values for each parameter; thus modeled estimates are likely to significantly exceed
actual exposures. For predicted environmental exposures, this is supported by a comparison of monitoring
results to modeling estimates. For consumer exposure, actual dermal absorption is less than 1% of product
(Schaefer and Redelmeier 1996), whereas all modeled exposures include a default assumption of 100%
absorption. Therefore, the modeled exposure is conservative by a factor of at least 100.
c) Several scenarios are not modeled—direct and indirect oral, inhalation, and sediment—but information
is presented to establish that exposure from these scenarios are not significant compared to the scenarios
that are discussed in detail.
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