Laboratory Degradation Rates of 11 Pyrethroids under Aerobic and Anaerobic Conditions

Abstract

Degradation of 11 pyrethroids was measured over approximately 100 days in three sediment/water systems under aerobic and anaerobic conditions at 25 °C in the dark. The three California sediments represented a range of textures and organic matter. Test compounds were bifenthrin, cypermethrin, ζ-cypermethrin, cyfluthrin, β-cyfluthrin, deltamethrin, esfenvalerate, fenpropathrin, γ-cyhalothrin, λ-cyhalothrin, and permethrin. A non-standard design was employed to keep conditions essentially the same for all compounds. The test compounds were applied as two test mixtures (six active ingredients per mixture, with bifenthrin common to both) at approximately 50 μg of test compound/kg of sediment (dry weight). Extracts of sediment/water were cleaned up by solid-phase extraction, concentrated, and analyzed by gas chromatography/mass spectrometry (except deltamethrin) against matrix-matched standards, with cyfluthrin-d6 as an internal standard. Deltamethrin was analyzed by liquid chromatography/tandem mass spectrometry using deltamethrin-phenoxy-(13)C6 as an internal standard. Similar degradation rates of bifenthrin and for related isomeric compounds (e.g., cyfluthrin and β-cyfluthrin) were generally measured in both mixtures for each sediment. First-order half-lives under aerobic conditions ranged from 2.9 to greater than 200 days, with a median value of 18 days. Under anaerobic conditions, the range was from 20 to greater than 200 days, with a median value of 70 days.

Characterization of cell-free extracts from fenpropathrin-degrading strain Bacillus cereus ZH-3 and its potential for bioremediation of pyrethroid-contaminated soils

“…It was reported that Bacillus genus could actively metabolize a variety of xenobiotic aromatic compounds as carbon sources (Cycoń et al, 2011;Meyer et al, 2013;Zhang et al, 2012). Our results showed that the cell-free extracts of B. cereus ZH-3 were capable of utilizing a wide range of pyrethroids.…”

“…Nowadays, biodegradation of pyrethroid contaminants has been a hot issue and numerous researches showed that various species of microorganisms were able to efficiently eliminate pyrethroid residues (Chen et al, 2012(Chen et al, , 2013aMeyer et al, 2013). Most bioremediation cases were realized by the direct contact between wide type microbes and target contaminants (Sharma et al, 2012;Zhang et al, 2011).…”

Measurement of Aquaculture Chemotherapeutants in Flocculent Matter Collected at a Hard-Bottom Dominated Finfish Site on the South Coast of Newfoundland (Canada) After 2 Years of Fallow

“…Degradation half-lives of chemotherapeutants can differ according to sediment type (Ernst et al, 2001;Meyer et al, 2013), presence of bacteria/opportunistic species, OM concentration and oxygenation state. Deltamethrin was shown to degrade slowly at 10 • C, whether incubated by itself or under its commercial formulation (t 1/2 = 330 ± 107 and 201 ± 27.1 d respectively).…”

“…Abiotic processes are predominant under reducing conditions (Tribovillard et al, 2006); these processes may lead to the depletion or formation of complexes, and the precipitation of sulfides and/or insoluble oxyhydroxides (Tribovillard et al, 2006). While deltamethrin degradation can occur through microbial action as well as hydrolysis and photolysis (Farghaly et al, 2013;Meyer et al, 2013), it may degrade less rapidly once adsorbed to OM-rich sediments (similarly to cypermethrin) (Benskin et al, 2016). The sorption of pyrethroids to flocculent matter is also highlighted by the observed correlation between pyrethroids and both OM content and distance to cage.…”

Environmental impact assessment of veterinary drug on fish aquaculture for food safety

“…For the registration of a pesticide, huge sets of data are required for toxicity and environmental impact studies, including risk assessment, but the same data has not been required for the registration of a veterinary drug in most countries. Even though VICH has suggested an environmental impact assessment guideline for veterinary drugs and environmental fate studies are required by the OECD 308 Test Guideline, and the US EPA guidelines OPPTS 835.4300 Aerobic Aquatic Metabolism and OPPTS 835.4400 Anaerobic Aquatic Metabolism, which include a study of degradation in an aquatic system, there have been few published examples of such work . As an internationally harmonized guideline, OECD 308 Test Guideline describes a laboratory test method to assess aerobic and anaerobic transformation of organic chemicals in aquatic sediment systems.…”