LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
eliminated via the urine, with sulfophenyl butanoic and sulfophenyl pentatonic acid as metabolites.
Approximately 35% of the absorbed dose was excreted in the bile. Although the metabolites in the
bile were not identified, it was shown that no unchanged LAS was eliminated via this pathway. In
oral studies with pigs, Havermann and Menke (1959) found that at 200 hours after oral
administration, the radiolabeled LAS was relatively high in bristles and bones, while low in liver,
kidney and spleen. After 10 weeks only traces of radioactivity were still in the body. At 40 hours
after administration, 40% of the dose was excreted into the urine and 60% of the dose via the feces.
In another study (Sunakawa et al. 1979), rats were dosed orally with 14C-LAS and radioactivity
was detected 0.25 hours after administraton, reaching a maximum at 2 hours. The biological halflife
was calculated to be 10.9 hours. The distribution was high in the digestive tract and in the
bladder at 4 hours after administration, with high concentrations also found in the liver, kidney,
testis, spleen and lung. At 168 hours after administration, the rates of excreted radioactivity were
47% in the urine and 50% in the feces.
Toxicokinetics has also been studied in adult rhesus monkeys (Cresswell et al. 1978). Two male
and two female monkeys were given single or repeated oral (30, 150 or 300 mg/kg) or subcutaneous
(0.1, 0.5 or 1 mg/kg) doses of 14C-LAS. For example, after single 30 mg/kg oral doses, the
radioactivity was rapidly excreted, mostly during the first 24 hours. Means of 71.2% and 23.1% of
the dose were excreted in the urine and feces, respectively, during 5 days. During seven
consecutive daily (30 mg/kg/day) or subcutaneous (1 mg/kg/day) doses, there was no accumulation
of radioactivity in plasma. Mean peak concentrations and biological half-lives were similar after
the first and seventh doses. No unchanged LAS was detected in the urine after oral or subcutaneous
doses. Five metabolites were excreted but they were not identified.
Studies in Humans
Studies were conducted with isolated human skin preparations using two solutions of C12 LAS
(Howes 1975). The results demonstrated that penetration through the skin and subsequent
absorption does not occur to any significant extent (less than 1%) at 24 to 48 hours.
3.1.2 Acute Toxicity
Acute mammalian toxicity data are available for all three potential routes of exposure (inhalation,
dermal, oral), as summarized below and in Table 5.
Studies in Animals
Oral
Eight acute oral toxicity studies are available for LAS using rats, and one acute oral study is
available using mice (Murmann 1984a,b,c; Ito et al. 1978; Kynoch 1986a; Monsanto 1971,
1972a,b). All of the studies were conducted on the low average chain length LAS (C11.2-C11.7).
The resultant LD50 values ranged from 1,080 up to 1,980 mg/kg bw for rats and greater than 2000
mg/kg bw for mice, with no significant difference between sexes. Mortality and symptoms of
toxicity occurred at the high doses tested in each study, and usually within the first few hours or
days, after which surviving animals generally recovered. Symptoms noted in most of the studies
included piloerection, hunched posture, abnormal gait (waddling), lethargy, reduced appetite,
decreased respiratory rate, ptosis, pallor of the extremities, and diarrhea. All oral studies are
reliability 1 or 2, except for those by Ito et al. (1978), which were rated unassignable (4) since the
original reports were not available for review. However, these studies were considered reliable
because they have been reviewed by the International Program on Chemical Safety.
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