Evaluating the sensitivity of a chronic plant bioassay relative to an independently derived predicted no-effect thresholds to support risk assessment of very hydrophobic organic chemicals.

Environmental risk assessments of very hydrophobic organic compounds (VHOCs) in soils are often difficult because multiple processes (e.g., sorption, volatilization, biodegradation) can complicate the interpretation of results.

Recommendations for advancing media preparation methods used to assess aquatic hazards of oils and spill response agents.

Laboratory preparation of aqueous test media is a critical step in developing toxicity information needed for oil spill response decision-making. Multiple methods have been used to prepare physically and chemically dispersed oils which influence test outcome, interpretation, and utility for hazard assessment and modeling. This paper aims to review media preparation strategies, highlight advantages and limitations, provide recommendations for improvement, and promote the standardization of methods to better inform assessment and modeling.

Using weight of evidence to assess degradation potential of UVCB hydrocarbon solvents.

Hydrocarbon solvents are a diverse group of petrochemical substances that are identified as unknown or variable composition, complex reaction products, or biological materials (UVCBs) and may contain tens of thousands of individual chemical constituents. As such, it is generally not possible to analytically resolve every chemical constituent in a hydrocarbon solvent. This, along with the low water solubility and/or high vapor pressure of constituents, precludes the use of many standardized tests designed to determine biodegradation in the environment (e.

Assessing toxicity of hydrophobic aliphatic and monoaromatic hydrocarbons at the solubility limit using novel dosing methods.

Reliable delineation of aquatic toxicity cut-offs for poorly soluble hydrocarbons is lacking. In this study, vapor and passive dosing methods were applied in limit tests with algae and daphnids to evaluate the presence or absence of chronic effects at exposures corresponding to the water solubility for representative hydrocarbons from five structural classes: branched alkanes, mono, di, and polynaphthenic (cyclic) alkanes and monoaromatic naphthenic hydrocarbons (MANHs). Algal growth rate and daphnid immobilization, growth and reproduction served as the chronic endpoints investigated.

Chronic toxicity of selected polycyclic aromatic hydrocarbons to algae and crustaceans using passive dosing.

Because of the large number of possible aromatic hydrocarbon structures, predictive toxicity models are needed to support substance hazard and risk assessments. Calibration and evaluation of such models requires toxicity data with well-defined exposures. The present study has applied a passive dosing method to generate reliable chronic effects data for 8 polycyclic aromatic hydrocarbons (PAHs) on the green algae Pseudokirchneriella subcapitata and the crustacean Ceriodaphnia dubia.

A novel passive dosing system for determining the toxicity of phenanthrene to early life stages of zebrafish.

Reliable experimental early life stage chronic toxicity data for fish are limited and further data are needed for polyaromatic hydrocarbons to establish environmental quality objectives and compare with toxicity model predictions. Efforts are underway to develop a zebrafish embryo toxicity test guideline to reduce, refine and replace the use of vertebrates in animal testing. An adaptation of this method which includes embryo lethal and sub-lethal developmental endpoints after a 5-day exposure as well as larval survival and growth endpoints during a subsequent 25-day test period is described using phenanthrene as a model test substance.