Environmental release, environmental concentrations, and ecological risk of N,N-Diethyl-m-toluamide (DEET).

N,N-Diethyl-m-toluamide's (DEET) commercial use as an insect repellent and other reported uses are reviewed. Evidence that DEET is reaching the environment mainly from consumer use of DEET-containing insect repellent includes studies reporting higher concentrations of DEET in surface water and wastewater samples during the summer months, the presence of DEET in on-site septic tank effluent at concentrations similar to that reported in wastewater treatment plant (WWTP) influent, and changes in WWTP effluent concentrations before and after the introduction of a DEET replacement in Germany. Its detected concentrations in influent and effluent of WWTP and surface water worldwide are reviewed and correlations between DEET usage and wastewater effluent concentrations are analyzed.

A comparative human health risk assessment of p-dichlorobenzene-based toilet rimblock products versus fragrance/surfactant-based alternatives.

A comparison of the human health risk to consumers using one of two types of toilet rimblock products, either a p-dichlorobenzene-based rimblock or two newer fragrance/surfactant-based alternatives, was conducted. Rimblock products are designed for global use by consumers worldwide and function by releasing volatile compounds into indoor air with subsequent exposure presumed to be mainly by inhalation of indoor air. Using the THERdbASE exposure model and experimentally determined emission data, indoor air concentrations and daily intake values were determined for both types of rimblock products.

Chemical structure-based predictive model for methanogenic anaerobic biodegradation potential.

Many screening-level models exist for predicting aerobic biodegradation potential from chemical structure, but anaerobic biodegradation generally has been ignored by modelers. We used a fragment contribution approach to develop a model for predicting biodegradation potential under methanogenic anaerobic conditions. The new model has 37 fragments (substructures) and classifies a substance as either fast or slow, relative to the potential to be biodegraded in the "serum bottle" anaerobic biodegradation screening test (Organization for Economic Cooperation and Development Guideline 311).

Estimating biodegradation half-lives for use in chemical screening.

Biodegradation half-lives are needed for many applications in chemical screening, but these data are not available for most chemicals. To address this, in phase one of this work we correlated the much more abundant ready and inherent biodegradation test data with measured half-lives for water and soil. In phase two, we explored the utility of the BIOWIN models (in EPI Suite) and molecular fragments for predicting half-lives.

A new biodegradation prediction model specific to petroleum hydrocarbons.

A new predictive model for determining quantitative primary biodegradation half-lives of individual petroleum hydrocarbons has been developed. This model uses a fragment-based approach similar to that of several other biodegradation models, such as those within the Biodegradation Probability Program (BIOWIN) estimation program. In the present study, a half-life in days is estimated using multiple linear regression against counts of 31 distinct molecular fragments.