Probabilistic Risk Assessment of Cotton Pyrethroids: I. Distributional Analyses of Laboratory Aquatic Toxicity Data

Abstract

This is the first in a series of five papers that assess the risk of the cotton pyrethroids in aquatic ecosystems in a series of steps ranging from the analysis of effects data through modeling exposures in the landscape. Pyrethroid insecticides used on cotton have the potential to contaminate aquatic systems. The objectives of this study were to develop probabilistic estimates of toxicity distributions, to compare these among the pyrethroids, and to evaluate cypermethrin as a representative pyrethroid for the purposes of a class risk assessment of the pyrethroids. The distribution of cypermethrin acute toxicity data gave 10th centile values of 10 ng/L for all organisms, 6.4 ng/L for arthropods, and 380 ng/L for vertebrates. For bifenthrin, cyfluthrin, lambda-cyhalothrin, and deltamethrin, the 10th centile values for all organisms were 15, 12, 10, and 9 ng/L, respectively, indicating similar or somewhat lower toxicity than cypermethrin. For tralomethrin and fenpropathrin, the 10th centiles were <310 and 240 ng/L, respectively. The distribution of permethrin toxicity to all organisms, arthropods, and vertebrates gave 10th centiles of 180, 76, and 1600 ng/L, respectively, whereas those for fenvalerate were 37, 8, and 150 ng/L. With the exception of tralomethrin, the distributions of acute toxicity values had similar slopes, suggesting that the variation of sensitivity in a range of aquatic nontarget species is similar. The pyrethroids have different recommended field rates of application that are related to their efficacy, and the relationship between field rate and 10th centiles showed a trend. These results support the use of cypermethrin as a reasonable worst-case surrogate for the other pyrethroids for the purposes of risk assessment of pyrethroids as a class.

Preliminary risk assessment of common-use pesticides using PRIMET and PERPEST pesticide risk models in a semi-arid subtropical region

“…However, its toxicity decreases significantly under natural in-field conditions as it undergoes microbial degradation, and also due to its good adsorptive properties (Schroer et al, 2004). Intensive application of deltamethrin causes toxicity to aquatic arthropods as well (Solomon et al, 2001). Deltamethrin is hydrophobic and has a high octanol-water coefficient which indicates a potential to bio-concentrate within aquatic organisms.…”

“…Deltamethrin is hydrophobic and has a high octanol-water coefficient which indicates a potential to bio-concentrate within aquatic organisms. The bio-concentration of this pesticide can potentially cause toxicity to aquatic invertebrates and fish (Van der Werf, 1996;Solomon et al, 2001). …”

Identifying the Causes of Sediment-Associated Toxicity in Urban Waterways of the Pearl River Delta, China

“…This method characterized relative sediment toxicity for a compound using criteria from water-only studies by Solomon et al 19 No LC50 values could be found for chlordane and hexachlorocyclohexane (BHC), thus probable effect concentrations (PEC) were used, 20,21 and PEC values were normalized to 1% TOC. Meanwhile, it should be noted that R-and γ-chlordane values were summed together for TU analysis, and γ-BHC sediment PEC values were used to quantify β-BHC predicted TUs, as data for β-BHC were not available.…”

Assessment of the Occurrence and Potential Risks of Pharmaceuticals and their Metabolites in Fish and Water Using Liquid Chromatography Mass Spectrometry

“…In recently years, probabilistic approach which determines the probability of an exposure concentration exceeding the probability of effects has been increasingly used in ERA procedures (Solomon et al 2001;Carriger and Rand 2008). This is because, when used correctly, it can introduce greater statistical confidence into risk assessment when compared to traditional hazard quotient and assessment factor approaches (Wheeler et al 2002).…”