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Contaminated groundwater from a pesticide production facility was assessed using whole-organism and in-vitro bioassays to determine the potential for these tests to replace or augment traditional chemical analyses being employed at this site. The groundwater, which is contaminated with a variety of pesticides (organochlorine, organophosphorus, and carbamate insecticides) and pesticide adjuvants (spreading agents, emulsifiers, etc.) was sampled from an activated-carbon-based on-site remediation system before, during, and after the cleanup procedure. Toxicity was evaluated at each point using whole-organism (96-h acute Pimephales promelas, chronic 3-brood Ceriodaphnia dubia) and in-vitro [submitochondrial particle (SMP) and MicrotoxR] bioassays. Chemical indicator parameters [pentachlorophenol, gasoline-range organics (GROs), and benzene, toluene, ethylbenzene, and xylenes (BTEX)] were also measured to compare with bioassay responses. 50% effective concentrations (EC50)s from the different tests indicate that the whole-organism assays were slightly more sensitive than the in-vitro assays: the order of sensitivity was C. dubia>P. promelas>SMP>MicrotoxR, but responses were quite similar. All assays showed decreasing toxicity as cleanup progressed, mimicking theconcomitant decrease in chemical concentration parameters. A toxicity identification evaluation (TIE) analysis, conducted using the in-vitro bioassays, identified pentachlorophenol as the major contributor to toxicity in the samples with additional contributions likely from other less-prevalent compounds. Results suggest that these in-vitro tests can be credible alternatives to whole-organism bioassays for monitoring remediation of system effluents and that they can complement chemical analyses with useful effects-based toxicity data. [ABSTRACT FROM AUTHOR]

Many studies on the toxicity of n-alkanols have been conducted and quantitative structure- activity relationships (QSARS) established comparing bioassay toxicity data to carbon number. The results typicallyindicate increasing toxicity with increasing n-alkanol chain length,but often higher homologues are not assessed, where toxicity no longer increases with carbon number -- a phenomenon commonly called the cutoff effect. The mode of toxic action of these compounds has been designated narcosis I; however, the specific mechanism is unknown and widely debated. This study compares results for two commonly used bioassays, the submitochondrial particle (SMP) and the Microtox(R) bioassay, for the homologous series of n-alkanols ranging from methanol (C1-OH) to stearyl alcohol (C18-OH). Analysis of dose-response curve slopes indicates that the SMP assay exhibits a general mechanism of toxicity, whereas the Microtox assay exhibits this general mechanism to short-chain alkanols, but subsequently switches to specific interaction with the higher alkanols. This specific interaction is likely competitive inhibition of the bacterial luciferase. Comparison of the toxicities in these assays with octanol/water partition coefficients (Kow), the re~ults of whole-organism tests, and a bacterial luciferase assay further substantiate this claim and indicate that the SMP is a better model of toxicity in whole organisms. [ABSTRACT FROM AUTHOR]

Decision-makers, scientists, and the interested public should be informed what future research and education is needed if a strong pesticide regulatory program is imposed. Recommendations are intended to highlight research gaps. Some may be of general concern and apply to many pesticides. A situation that calls into question the value of many of our management decisions, is the lack of good field-scale experimentation and of logical mechanisms for translating and extrapolating laboratory data to field-scale dimensions. Many experiments were not designed to allow application of basic statistical criteria. High costs often preclude sufficient replication in field-scale experiments so that researchers must make the "no-win" choice between doing one investigation well or doing two or three poorly. The following observations about alachlor and metolachlor are provided: Pysicochemical properties are accurately determined. The herbicides' modes of action and plant selectivity have received a great deal of attention, but gaps remain in defining which of three modes of action are most important. Geographic distribution and extent of residue contamination of surface waters is documented, but groundwater contamination is poorly defined. Any groundwater monitoring protocol should limit the investigation based on sound scientific judgment since a nationwide monitoring network cannot be economically justified. Enough data are needed, however, to allow mathematical model development, verification and validation for a diversity of soil, geographic, climatic, and agricultural management conditions. In view of the importance of adsorption in determining the fate of pesticides, improved methods of determining adsorption coefficients (KD) are needed particularly for very low concentrations. The impact of soil aggregation on adsorption/desorption needs to be examined. The role of temperature and water content in adsorption/desorption processes needs clearer definition. Although volatilization is probably of limited concern for herbicides with Henry's Law constants less than 10(-5), better field-scale methods of estimating volatilization are needed. Lack of clear relationships between laboratory and field investigations is particularly acute in leaching studies. Differentiation between transport rates in the root and vadose zones are limited. Methods of sampling water in the vadose zone await innovative technology. Techniques to confine pesticides to the root zone or to retard their movement beyond the root zone are needed. Management strategies must protect groundwater by curtailing movement or reducing pesticide use. Losses of chloracetanilide herbicides through surface runoff and erosion is poorly documented. When erosion control was linked to soil productivity, use of small plot experiments was probably justified. If improved surface water quality is a goal, small plot findings must be extrapolatable to large watersheds.(ABSTRACT TRUNCATED AT 400 WORDS)

The first known cleavage by a bacterium of an arylglycerol-beta-aryl ether linkage, the most common intermonomer linkage in lignin, is described.

Syringaldazine did not turn purple on cross sections of tree branches or saplings or on cambial tissue cultures unless hydrogen peroxide was added; this indicated the absence of laccase but presence of peroxidase in lignifying cells. Peroxidase, therefore, apparently is the only en enzyme that polymerizes p-coumaryl alcohols to lignin in trees.