Acute toxicity C12LAS

LAS. The toxicity of C12LAS to aquatic organisms has been widely studied and is reported to span a wide concentration range (Table II see ref. 65 for a more extensive review the references we report in this chapter were selected for applicability to the United States and Europe and for data quality). The toxicity mechanism of LAS and other surfactants (AS and AES) is unknown but is suspected to be polar narcosis. Acute toxicity to invertebrate species (48-h hC ) range from 1.7 mg/L for the oligochaete, Dero,... 

The available C12LAS acute toxicity data for fish indicate little intraspecies variability (Table II). For the four species tested, the 96-h LCso concentrations of C12LAS range from 1.2 mg/L for the fathead minnow Pimephales promelas (64) to 6.2 mg/L for the minnow Phoxinus phoxinus (68). Although the variety of species tested is not as broad as for the invertebrates, the available data suggest that sensitivity of fish to C12LAS is similar to that of the most sensitive invertebrates. 

No studies on the acute toxicity of C12LAS to algae and aquatic plants were found in the literature. Typical toxicity-testing protocols use a test duration of 4-7 days. This duration of testing represents a significant portion of the organisms life span for the taxa tested. Thus these toxicity tests are appropriately considered chronic-toxicity tests. 

Table II, Acute Toxicity of C12LAS to Invertebrates and Fish...

For the effect level, application of the invertebrate acute-to-chronic ratio to the most acutely sensitive invertebrate species, Dero, generates a chronic toxicity value of 0.6 mg/L. This value compares favorably with the measured NOECs of 1.2 and 1.4 mg/L, respectively, for the invertebrates Daphnia magna and Ceriodaphnia dubia. The fish species most sensitive to C12LAS chronic toxicity is the fathead minnow, Pimephales promelas. Most recently, Fairchild et al. (64) reported a chronic C12LAS NOEC of 0.7 mg/L for the fathead minnow. This NOEC compares favorably with the NOEC of 1.1 mg/L reported by Holman and Macek (66) for the same species. 

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