SIAM 20, 19-21 April 2005

US/ICCASIDS INITIAL ASSESSMENT PROFILECAS Nos.

1322-98-1
Decylbenzene sulfonic acid, sodium salt
25155-30-0 Dodecylbenzene sulfonic acid, sodium salt
26248-24-8 Tridecylbenzene sulfonic acid, sodium salt
27636-75-5 Undecylbenzene sulfonic acid, sodium salt
68081-81-2 C 10-16 Monoalkylbenzene sulfonic acid, sodium salt
68411-30-3 C 10-13 Alkylbenzene sulfonic acid, sodium salt
69669-44-9 C 10-14 Alkyl deriv benzene sulfonic acid, sodium salt
85117-50-6 C 10-14 Monoalkylbenzene sulfonic acid, sodium salt
90194-45-9 C 10-13 Alkyl deriv benzene sulfonic acid, sodium salt
127184-52-5 4-C 10-13 -sec Alkyl deriv. benzene sulfonic acid,sodium salt

Category Name

Linear Alkylbenzene Sulfonate (LAS)This structure of a C 12 -LAS is representative of the category.
CH3(CH2)5CH(CH2)4CH3

Structural Formula

S03 - Na+SUMMARY CONCLUSIONS OF THE SIAR
Category Identification/ Justification
The LAS molecule contains an aromatic ring sulfonated at the para position and attached to a linear alkyl chain at anyposition except the terminal carbons. The alkyl carbon chain typically has 10 to 14 carbon atoms and the linearity of
the alkyl chains ranges from 87 to 98%. While commercial LAS consists of more than 20 individual components, theratio of the various homologs and isomers, representing different alkyl chain lengths and aromatic ring positions along
the linear alkyl chain, is relatively constant in currently produced products, with the weighted average carbon numberof the alkyl chain based on production volume per region between 11.7-11.8. LAS are supported as a category
because of the close consistency of the mixtures, their commercial uses, fate, and health and environmental effects.
LAS is the primary cleaning agent used in many laundry detergents and cleaners at concentrations up to 25 percent in
consumer products, and up to 30 percent in commercial products, with the exception of one reported product at 45%
percent in concentrated solid form that is mechanically dispensed into diluted solution for dishwashing.
Human Health
Substantial data exist for mammalian toxicity. The available data indicate that LAS exhibits slight acute toxicity.
Oral LD50 values for rats range from 1,080 to 1,980 mg/kg bw. Oral LD50 values for mice are 2,160 and 2,250 mg/kg
bw for males and females, respectively. The rat dermal LD50 value was greater than 2,000 mg/kg bw. The oral anddermal acute toxicity data for LAS generally indicate low hazard potential when all studies are considered together.
Acute inhalation toxicity data indicate that LAS is moderately toxic, with mortality occurring at respirable particle
concentrations of 310 mg/m3 (MMAD = 2.5 microns).
This document may only be reproduced integrally. The conclusions and recommendations (and their rationale) in thisdocument are intended to be mutually supportive, and should be understood and interpreted together.

SIAM 20, 19-21 April 2005

US/ICCAIn a series of studies on rabbits, LAS was not irritating to the skin or eyes at low concentrations (0.5-2.5%),
moderately irritating at 5%, and more severely irritating at higher (about 50%) concentrations. In studies that
included rinsing, eye irritation effects diminished with rinsing after 30 seconds of exposure and were slight withrinsing after 4 seconds of exposure. In a low volume eye test (LVET) using a 35% LAS solution, rabbits experienced
moderate irritation that was completely reversible by day 35. (Note that the maximum concentration of LAS is 25
percent in consumer products and normally less than 30 percent in commercial products.) Accidental eye exposure in231 manufacturing employee incidents and 284 consumer incidents established that eye irritation effects of exposure
during manufacturing and use of products containing LAS and other surfactants are moderate, transient andreversible.
In 15 repeated dose studies with rats, mice, and monkeys exposed to LAS via oral and dermal routes, LOAELs ranged
from 115 to 750 mg/kg bw/day. The corresponding NOAELs ranged from 40 to 250 mg/kg bw/day. Effects
commonly observed included suppressed body weight gain, diarrhea, increases in relative liver weight, differences inenzymatic and serum-biochemical parameters, and mild degeneration and desquamation of the tubular epithelium inthe kidneys.
In four well designed in vitro bacterial (Salmonella) mutagenicity studies, LAS shows no evidence of mutagenicityeither with or without S9 metabolic activation. LAS showed no evidence of causing increased cell transformation in
an in vitro cell transformation assay. In in vivo studies, no significant differences in chromosome aberrations wereseen when mice were given either oral doses up to 800 mg/kg bw/day or dietary doses up to 1170 mg/kg bw/day. In amouse micronucleus study, LAS did not induce a clastogenic effect. Rats given dietary doses up to 450 mg/kg
bw/day also showed no significant differences in chromosome aberrations. Collectively, these data support that LASis not genotoxic.
The highest dose tested in four carcinogenicity studies with rats was 300 mg/kg bw/day. In the most documented
study, rats were administered up to 250 mg LAS/kg body weight/day in the diet for two years. Results of this study
indicate no gross or histopathological evidence of a carcinogenic effect. No evidence of tumorigenesis was observedin any of the carcinogenicity studies. While the quality and focus of the studies precludes a definitive assessment, theresults of the genetic toxicology and rodent bioassay studies collectively provide strong weight-of-evidence support
that LAS is not genotoxic and is not a rodent carcinogen.
Similarly, no evidence of reproductive or fertility effects was observed in any of the three available reproductive
toxicity studies in which rats were given dietary doses over three to four generations. NOAELs from these
reproductive studies ranged from 70 to 350 mg/kg bw/day, which were the highest doses tested. In 17 developmental
toxicity studies, effects such as embryo death or deformities, and litter loss were most often observed only atmaternally toxic doses and were associated with the irritation effects of LAS on skin or the gastrointestinal tract. No
decreases in litter size, no changes in litter parameters, no malformations or significant differences in skeletal defects
were observed at oral doses up to 780 mg/kg bw/day in rats and at dermal doses of 500 mg/kg bw/day in mice and 90
mg/kg bw/day in rabbits.
All of the studies included in the dossier are considered reliable, but all with limitations. The results are consistent
with each other and these data are used in a weight-of-evidence approach. Based on these considerations, the highest
NOAEL value below the lowest LOAEL from all of the mammalian toxicity studies is the most appropriate.
Therefore, the NOAEL is 85 mg/kg bw/day. This value comes from a rat drinking water, 9-month repeated dose
toxicity study. The lowest LOAEL (115 mg/kg/day) was associated with increased weight of the cecum and slightdegeneration of the renal tubules.
Environment
Pure LAS is a solid at ambient temperatures with a melting point of 198.5°C. The boiling point for LAS could not
be determined experimentally due to decomposition beginning at 444°C. LAS has a low vapor pressure (calculatedas 3-5 x 10-13 Pa). LAS is water soluble, with a critical micelle concentration (CMC) value of 0.1 g/L and forms aclear solution in water at concentrations up to 250 g/L. Although it is impossible to accurately measure an octanolThis document may only be reproduced integrally. The conclusions and recommendations (and their rationale) in thisdocument are intended to be mutually supportive, and should be understood and interpreted together.

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US/ICCA

water partition coefficient for surface-active agents like LAS, an octanol-water partition coefficient of log 3.32 hasbeen calculated for C11.6 LAS. Kd values for LAS in activated sludge and sediment increased with increasing alkyl
chain length of LAS homologues with Kd values for C12 LAS of 3210 L/kg in activated sludge and 330 L/kg in river
sediment. In activated sludge, sorption and desorption equilibria for LAS were achieved very rapidly, andcomparison of the extent of sorption and biodegradation shows that the absorbed fraction as well as the soluble
fraction of LAS is available for biodegradation. Based on Fugacity III modeling results using the most relevant input
parameters, more than 99 percent of the residual (non-biodegraded) fraction of LAS distributes to the soil. LAS does
not undergo significant degradation by abiotic mechanisms under environmentally relevant conditions as
photolyzable and hydrolyzable groups are absent from the chemical structure.
An extensive database of studies demonstrates rapid and complete (ultimate) biodegradation of LAS in many of theavailable aerobic biodegradation tests, including soil and the aqueous environment. In several tests, LAS has beenshown to be readily biodegradable, and has passed the 10-day biodegradation window in mineralization tests formost ready tests. LAS is removed in biological wastewater treatment at percentages ranging from 77-82% fortrickling filters up to 99%+ for activated sludge. The biodegradation kinetics of the longer alkyl chain lengths are
generally faster, and their sorption coefficients larger. The primary degradation intermediates are sulfophenyl
carboxylates (SPCs), which further degrade to CO2, SO42-, and water. LAS does not generally degrade underanaerobic conditions. The measured bioconcentration factors of pure homologues and isomers decrease withdecreasing average alkyl chain lengths (from almost 1000 for 2-phenyl-C13 LAS to 2 for 6-phenyl-C10 LAS), all with
rapid clearance. The calculated BCF for currently produced C11.6 LAS is 87 and was 22 for filtered Mississippi
River water (average alkyl chain length of surface water fingerprint = C10.8).
Ecotoxicity data are extensively available for LAS, with several comprehensive reviews having been completed. The
lowest reliable acute LC50/EC50/ErC50 values based on a review of the aquatic toxicity data on commerciallyrepresentative LAS (C11.6-C11.8) were 1.67, 1.62 and 29.0 mg/L for fish, Daphnia magna, and algae, respectively.
Acute toxicity is greater for individual LAS homologues with longer alkyl chain lengths. LAS biodegradationintermediates are significantly less toxic than the parent LAS with L/EC50 values >1000 mg/L for fish and D. magna.
Chronic freshwater toxicity studies following guideline exposures (28-30 days for fish, 21 days for invertebrates and3-4 days for algae provided the following NOEC values: fish NOEC = 1 mg/L (two studies, two species); Daphnia,NOEC = 1.18-3.25 mg/L (six values, two studies, one with 5 diets); algae, NOEC = 0.4-18 mg/L (four studies, twospecies). In addition all of the available, reliable chronic single species aquatic toxicity data on LAS have been
evaluated, including three freshwater species in which multiple studies were reported and nine freshwater species forwhich single studies were reported. Single NOEC values and geometric mean NOEC values (calculated for species
with multiple results) were normalized to C11.6 LAS. These NOEC values range from 0.25 to 6.1 mg/L for freshwater
species, including fish, invertebrates, algae and higher plants. Geometric mean NOEC values for marine species
ranged from 0.025 to 5.0 mg/L. Based on the model ecosystem studies, a NOEC of 0.27 mg/L (0.37 if normalized toC11.6 LAS) was determined for the freshwater ecosystem. This value is based on model stream ecosystem studies ofover 250 species, and is consistent with the single species chronic freshwater data.
NOEC values for sediment exposures were greater than or equal to 81 mg/kg dry matter based on studies in fourspecies, including GLP studies in L. variegates (survival, reproduction and growth over 28 days) and C. elegans (eggproduction, 3 days). Field studies indicate no adverse effects of LAS in sludge-amended soil from LAS levels of 15
mg/kg dry matter in the soil (9 microbial functions/processes and abundance/diversity of microarthropods andearthworms, short-term and 4 years) or 31,300 mg/kg dry matter in sludge (function of microbial community, shortterm and 1 year).
In laboratory studies in which young trees are exposed to artificial sea spray, LAS concentrations of 10 mg/L lead toincreased foliar penetration of NaCl, a hypothesized mechanism of defoliation.
A health and environmental risk assessment is available (heraproject.com).
Exposure
Current LAS production is approximately 390,000 metric tons in the North America, 400,000 metric tonnes inThis document may only be reproduced integrally. The conclusions and recommendations (and their rationale) in thisdocument are intended to be mutually supportive, and should be understood and interpreted together.

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Europe, and 85,000 metric tonnes in Japan. Global production was 2.6 million metric tonnes in 1995. In theproduction phase, manufacturing processes have been designed to maximize production yield and minimize potentialreleases. Worker exposure is possible during the detergent formulation stage by inhalation of powders or dermal
contact of powders and liquids. Good manufacturing design practices (e.g., enclosed production in agglomeration
processes, exhaust ventilation, dust collection) and personal protective equipment (e.g., protective clothing, eyewear,and gloves) in place at facilities that manufacture liquid and dry (granular/powder) materials are anticipated tomitigate worker exposure to LAS. Any LAS that is not incorporated into a product is captured by dust-handlingequipment for recycling back into the production process. A limited amount of LAS in aqueous solution may bereleased as a dilute solution from washing and rinsing operations in the manufacturing process and is discharged towastewater treatment. Incidental quantities of the dry (granular/powder) product (e.g., from floor sweepings) may bedisposed in landfills.
Labeling of consumer products containing LAS and other surfactants include warnings of the potential for eye
irritation and first aid instructions to rinse with water.
Data suggest that inhalation of LAS products during use will be low. Spray products containing LAS are designed
to produce the large particle sizes needed for efficient delivery of the spray to the surface being cleaned. In
laboratory simulations with six spray nozzles representing those used in spray cleaning products, less than 0.1% of
the total volume sprayed consists of respirable particles (particles under 10 microns in diameter) and air
concentrations in the breathing zone are in the 0.13-0.72 mg/m3 range. Inhalation of detergent dusts during washingprocesses, modeled by HERA (2004), was 10-fold lower than inhalation of aerosols from cleaning product sprays.
This estimate is based on a published study reporting an average of 0.27 µg dust per cup of product used for machinelaundering. This is a conservative (protective) estimate as exposure from modern compact/granular detergent
formulations produced in agglomeration processes, which produce larger particle sizes, would be expected to bemuch less. Based on these data, it is expected that exposures to respirable particles from inhalation are low.
Results of extensive environmental monitoring evaluations in the United States indicate that measured surface water
concentrations were generally below 50 µg/L for river water samples collected under low dilution (worst case)conditions below treatment plant mixing zones. Values in the 2800 km reach of the Mississippi River fromMinneapolis to New Orleans range from non-detect (<0.1 µg/L) to 28 µg/L (362 samples). LAS river water
concentrations similar to those in the US were observed in monitoring studies conducted in Europe and Japan.
Measured LAS concentrations in river sediments were generally less than 1-2 mg/kg dry weight. Mississippi Riversediments were <1 mg/kg dry matter with one exception. LAS levels in sediments of the receiving waters of theTiber River (Italy) were 1.8 mg/kg dry matter. Higher LAS concentrations have been observed near untreated or
poorly treated wastewater discharges, e.g. LAS in sediments of a small river (Rapid Creek, USA) below a trickling
filter treatment plant averaged 190 mg/kg just below the outfall, 11.2 mg/kg less than 5 miles downstream and 5.3
mg/kg greater than 5 miles downstream

RECOMMENDATION AND RATIONALE FOR THE RECOMMENDATION AND NATURE
OF FURTHER WORK RECOMMENDED
Human Health: The chemicals in the LAS category are currently of low priority for further work because of their lowhazard potential except for skin and eye irritation and acute inhalation. Based on data presented by the Sponsor
Country, exposure to respirable particles is anticipated to be low. Other countries may desire to investigate any
exposure scenarios that were not presented by the Sponsor Country.
Environment: The chemicals in the LAS category possess properties indicating a hazard for the environment (fish,invertebrates and algae). However, they are of low priority for further work due to ready and/or rapid biodegradationand limited potential for bioaccumulation.

This document may only be reproduced integrally. The conclusions and recommendations (and their rationale) in thisdocument are intended to be mutually supportive, and should be understood and interpreted together.