Whole sediment toxicity identification evaluation tools for pyrethroid insecticides: III. Temperature manipulation

Abstract

Since the toxicity of pyrethroid insecticides is known to increase at low temperatures, the use of temperature manipulation was explored as a whole-sediment toxicity identification evaluation (TIE) tool to help identify sediment samples in which pyrethroid insecticides are responsible for observed toxicity. The amphipod Hyalella azteca is commonly used for toxicity testing of sediments at a 23 degrees C test temperature. However, a temperature reduction to 18 degrees C doubled the toxicity of pyrethroids, and a further reduction to 13 degrees C tripled their toxicity. A similar response, though less dramatic, was found for 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), and dissimilar temperature responses were seen for cadmium and the insecticide chlorpyrifos. Tests with field-collected sediments containing pyrethroids and/or chlorpyrifos showed the expected thermal dependency in nearly all instances. The inverse relationship between temperature and toxicity provides a simple approach to help establish when pyrethroids are the principal toxicant in a sediment sample that could be used as a supplemental tool in concert with chemical analysis or other TIE manipulations. The phenomenon appears to be, in part, a consequence of a reduced ability to biotransform the toxic parent compound at cooler temperatures. The strong dependence of pyrethroid toxicity on temperature has important ramifications for predicting their environmental effects, and the standard test temperature of 23 degrees C dramatically underestimates risk to resident fauna during the cooler months.

Does cadmium affect the toxicokinetics of permethrin in Chironomus dilutus at sublethal level? Evidence of enzymatic activity and gene expression

“…Coefficients of determination for both exposures were approximately 0.7, indicating a good fitting to the model (Table 2). Toxicokinetic parameters, including k u , k e and t 1/2 of permethrin in the midges were comparable with the previously reported values within a factor of 2 (Weston et al, 2009). Weston et al (2009) used 14 C-radiolabeled chemicals to track the biotransformation of permethrin in the midges and fitted the data to a two-compartment model.…”

The contribution of pyrethroid pesticides to sediment toxicity in four urban creeks in California, USA

“…Pyrethroid-specific TIE treatments for whole sediment have been thoroughly evaluated and their use is becoming more routine. [4][5][6]23,30,31) In the current study, the results of the whole sediment treatments provided valuable TIE evidence, but were variable in some samples. Samples which had a high magnitude of toxicity such as Bouquet and Marsh Creeks were not analyzed using TIE treatments that increase toxicity, but could have been evaluated by treating a dilution series of the sediments.…”

“…An increase in sample toxicity at the lower test temperature was considered additional evidence of pyrethroid toxicity. 23) Whole sediment TIEs on the Cottonwood and Peters Canyon samples did not include the latter two treatments because complete mortality was observed in these samples and toxicity could not be increased.…”

“…A recent study has demonstrated that a temperature reduction of 5°C increases the toxicity of pyrethroids to H. azteca two-fold, and a reduction of 10°C increases the toxicity three-fold. 23) These increases would be dependent on the concentrations of pyrethroids in the sediment.…”

“…This technique has been shown to provide additional lines of evidence of pyrethroid toxicity using PBO addition and temperature manipulation. 23,30) This approach can be labor intensive, but is recommended for sediments showing variable TIE response signatures.…”