Bioconcentration, biotransformation, and chronic toxicity of sodium laurate to zebrafish (Danio rerio)

Abstract

Abstract-The chronic toxicity of sodium laurate (dodecanoic acid, sodium salt; CAS 629-25-4) to zebrafish (Danio rerio) was determined in a 28-d growth rate study. The laurate did cause lethal effects, but a reduction in growth was not observed at sublethal exposure concentrations. The 15-d median lethal concentration was 7.6 mg/L, which is similar to the theoretical and measured solubility limit of laurate under the test conditions. The 28-d no-observed-effect concentration (lethality) was 2 mg/L, whereas growth was not impaired at 6.4 mg/L in survivors after 28 d. Laurate was extensively biotransformed to metabolites, including less polar compounds, possibly triacylglycerols. At the end of the exposure period, which was considered long enough for steady state to be achieved, the bioconcentration factor of laurate was estimated to be 255 L/kg. Body burdens of nonmetabolized laurate for surviving fish were up to 10-fold higher (2.7-8.7 mmol/kg) than the chronic critical (sublethal) body residues (0.2-0.8 mmol/ kg) proposed for nonpolar or polar narcotics.

Surfactant partitioning in cloud droplet activation: a study of C8, C10, C12 and C14 normal fatty acid sodium salts

“…The fatty acids are weak: pK a is 4.89 for caprylic acid (CRC, 2004–2005), 4.9 for capric acid (Stahl and Wermuth, 2002), 5.3 for lauric acid (Van Egmond et al, 1999) and approximately 5.8 for myristic acid (Wen and Franses, 2000). We have not considered the various effects of carboxylate ion protonation explicitly in the model calculations, since droplet solutions at activation are predicted to be rather dilute (<0.1 M for the ‘partitioning’ approach and <0.5 M for the ‘σ w ’ approach, all dry particle sizes and compositions considered) and the protonation equilibrium therefore is shifted greatly in favour of the carboxylate ion form (e.g.…”

Predicted no‐effect concentrations and risk characterization of four surfactants: Linear alkyl benzene sulfonate, alcohol ethoxylates, alcohol ethoxylated sulfates, and soap

“…The lowest EC50 is for lauric acid tested on Daphnia magna . The only available longterm NOEC is from a 28‐d growth test with sodium laurate, resulting in 3.7 mg/L for Brachydanio rerio [49].…”

Bioconcentration and biotransformation of the nonionic surfactant octaethylene glycol monotridecyl ether 14C‐C13EO8

“…Lipid content was quantified as the weight of the dry hexane extract of MSPD [24,25]. Less than 5% of the radioactivity of lauric acid appeared to be retained by MSPD columns after elution with MeOH [26]. The use of MeOH: H 2 O (1:1) allows us to extract radioactivity incorporated into even more polar molecules.…”