HUMAN HEALTH

The presence of LAS in many commonly used household detergents gives rise to a variety of possible consumer contact scenarios including direct and indirect skin contact, inhalation, and oral ingestion derived either from residues deposited on dishes, from accidental product ingestion, or indirectly from drinking water.

HUMAN TOXICITY

Acute toxicity

The oral toxicity is greater than 3000 mg/kg bw (Huntingdon, 1984) and the dermal toxicity is greater than 2000 mg/kg bw (Huntingdon-a, 1986).

LAS is severely irritating to the eye at concentrations of about 50%, while is moderately irritating at 5% and non-irritating at 1% (Huntingdon-b, 1986; BIOLAB, 1988; BIOLAB-b, 1989; BIOLAB, 1983). The irritating effects diminishes with rinsing after the exposure.

LAS is irritating to skin at a concentration of about 50% after 4 hours of exposure, while it is moderately irritating at a concentration of 5%, and not irritating at 2.5%, after 24 hours exposure.

Sensitisation

LAS is not a contact sensitiser, on the basis of both animal (Hüls, 1988; Procter & Gamble, 1985; RBM, 1985), and human volunteer tests (Procter & Gamble, 1997).

Repeated dose toxicity

Many studies are available for the repeated dose oral toxicity. In view of the available information it is not possible to determine which single study is the most reliable or appropriate for the determination of a NOAEL. Because of that, based on data from all the studies, a NOAEL (No Observed Adverse Effect Level) of 85 mg/kg bw d is proposed, which is the NOAEL value closest to the lowest available LOAEL (Lower Observed Adverse Effect Level) (115 mg/kg bw d). This NOAEL is the dose with no effects on renal biochemical parameters that has been observed in a 9-month study of oral toxicity in rats (Yoneyama et al., 1976*).

Genotoxicity

In all in vitro and in vivo assays there is no indication of genetic toxicity for LAS (Hüls, 1993; Inoue et al., 1979 and 1980; Sunakawa et al., 1981*).

Carcinogenicity

The oral long-term studies performed did not indicate any potential for carcinogenicity of LAS and showed no effects or histopathological findings at doses up to 300 mg/kg bw d (Buehler et al., 1971; Fujii. et al., 1977 Yoneyama et al., 1977; Endo et al., 1980 *).

Reproductive toxicity

Results of studies on reproduction fail to show any adverse effects at any of the doses tested.

Developmental toxicity and teratogenicity

Some findings of maternal toxicity were found at low or relatively low doses, administered dermally and by gavage to rats, mice and rabbits, but they are associated with irritation effects of LAS, either on the skin or the gastrointestinal tract.

In other oral studies no effects were found in parental animals up to 780 mg/kg bw d. To sum up, some effects, such as embryo death or deformities, decrease in pregnancy rate and litter loss were noted in some studies at maternal toxic doses, but in general no decreases in the litter size, no changes in the litter parameters, no malformations or significant difference in skeletal defects were observed at oral doses up to 780 mg/kg (Tiba et al., 1976 *) and at dermal doses up to 1500 mg/kg bw d (Imahori et al., 1976 *(*) Japanese studies reported in IPCS, 1996).

Key references

Van de Plassche et al., 1999
Belanger et al., 2002
Holmstrup et al., 2001-a
Jensen et al., 2001
Huntingdon-a, 1986
Huntingdon-b, 1986
RBM, 1985
Buehler et al., 1971