Evaluating environmental hazards of land applying composted diazinon using earthworm bioassays.

Environmental hazards resulting from land application of composted pesticide residue have not been rigorously evaluated. This study was conducted to examine the toxicity of a composted pesticide residue using earthworms (Eisenia foetida Savigny) as a microinvertebrate model in a soil bioassay system. Diazinon, which was used in these experiments as a test pesticide, was removed from simulated rinsate (wastewater) by sorption onto peat moss. Following the rinsate clean-up phase, diazinon-laden peat moss was placed into bioreactors and composted for either 30 or 60 days. Earthworms were then exposed to soil amended with the composted material. Mortality and symptomatic effects characteristic of acetylcholinesterase inhibition, including weight loss, reduced burying ability and curling, occurred in earthworms exposed to soil amended with either uncomposted or 30-day composted diazinon, but not in those exposed to soil amended with 60-day composted diazinon. The amount of solvent-extractable diazinon from compost was not directly related to acute earthworm toxicity based on the selected criteria. These results indicated a reduction in diazinon bioavailability during latter 30 d of composting that did not correspond to a reduction in solvent-extractable diazinon concentrations. Measuring symptomatic effects of xenobiotics as described in this study may increase the sensitivity and diagnostic ability of earthworm bioassays.

Fate of atrazine and chlorpyrifos during solid state fermentation--examination of processes.

Solid state fermentation (SSF) was investigated as a means to dispose of two commonly used pesticides, chlorpyrifos (O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate) and atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine). SSF experiments were carried out in bench-scale bioreactors (equipped with CO2 and volatile organic traps) containing a mixture of lignocellulosic materials and a radiolabeled pesticide. Ethyl acetate-extractable, alkali soluble, and alkali insoluble fractions were evaluated for radioactivity following a 60-d incubation period at 40 degrees C. The majority of the [2,6-pyridyl-14C]chlorpyrifos was associated with the ethyl acetate extract (about 74%), 17% was trapped as organic volatiles by polyurethane foam traps and < 0.5% of the chlorpyrifos was mineralized to CO2. Only small amounts of the radioactivity were associated with alkali soluble (0.0003%) and alkali insoluble (0.3%) fractions. In the [14C-U-ring]atrazine bioreactors, very little of the radioactivity volatilized (<0.5%) and less than 0.5% was mineralized to CO2. Approximately 57% of the applied radioactivity was associated with the ethyl acetate extract while 9% and 24% of the radioactivity was associated with the alkali soluble (humic and fulvic acids) and alkali insoluble fractions, respectively. Possible reaction mechanisms by which covalent bonds could be formed between atrazine (or metabolites) and humic substances were investigated. The issue of bound atrazine residue (alkali soluble fraction) was at least partially resolved. Oxidative coupling experiments revealed that formation of covalent bond linkages between amino substituent groups of atrazine residue and humic substances is highly unlikely.

Degradation of dicamba by an anaerobic consortium enriched from wetland soil.

The biodegradability of dicamba was investigated under anaerobic conditions with a consortium enriched from wetland soil. Degradation proceeded through an initial demethylation reaction, forming 3,6-dichlorosalicylic acid, followed by reductive dechlorination, forming 6-chlorosalicylic acid. The consortium, consisting of a sulfate reducer, three methanogens, and a fermenter, was unable to mineralize the aromatic ring.

Metabolism of 3-methylindole by a methanogenic consortium.

A methanogenic 3-methylindole (3-MI)-degrading consortium, enriched from wetland soil, completely mineralized 3-MI. Degradation proceeded through an initial hydroxylation reaction forming 3-methyloxindole. The consortium was unable to degrade oxindole or isatin, suggesting a new pathway for 3-MI fermentation.

Degradation of substituted indoles by an indole-degrading methanogenic consortium.

Degradation of indole by an indole-degrading methanogenic consortium enriched from sewage sludge proceeded through a two-step hydroxylation pathway yielding oxindole and isatin. The ability of this consortium to hydroxylate and subsequently degrade substituted indoles was investigated. Of the substituted indoles tested, the consortium was able to transform or degrade 3-methylindole and 3-indolyl acetate. Oxindole, 3-methyloxindole, and indoxyl were identified as metabolites of indole, 3-methylindole, and 3-indolyl acetate degradation, respectively. Isatin (indole-2,3-dione) was produced as an intermediate when the consortium was amended with oxindole, providing evidence that degradation of indole proceeded through successive hydroxylation of the 2- and 3-positions prior to ring cleavage between the C-2 and C-3 atoms on the pyrrole ring of indole. The presence of a methyl group (-CH3) at either the 1- or 2-position of indole inhibited the initial hydroxylation reaction. The substituted indole, 3-methylindole, was hydroxylated in the 2-position but not in the 3-position and could not be further metabolized through the oxindole-isatin pathway. Indoxyl (indole-3-one), the deacetylated product of 3-indolyl acetate, was not hydroxylated in the 2-position and thus was not further metabolized by the consortium. When an H atom or electron-donating group (i.e., -CH3) was present at the 3-position, hydroxylation proceeded at the 2-position, but the presence of electron-withdrawing substituent groups (i.e., -OH or -COOH) at the 3-position inhibited hydroxylation.

Soil and groundwater transport of microorganisms.

Releases of GEMs into the environment are expected to increase in the next few years, with the most dramatic increases resulting from the application of pest-control agents in agriculture and forestry. Of major significance in assessing the environmental risk impact of GEMs is an understanding of their survival and transport in soil and subsurface environments. While information on the transport and survival of microorganisms through soil is available, it is neither abundant nor extensive in terms of microbial types tested or soils examined. Though the transport of microorganisms from an application site depends primarily upon passive mechanisms, broad generalizations pertaining to the transportability of a specific microorganism within a particular soil environment may not be possible. Indeed, to extrapolate from information about one microbe to another, or from one geographical location to another, may not be appropriate. What is clear, however, is that the broader the data base, the more powerful the argument for making reasoned judgement, and consequently the more satisfactory the results of the predictive process. Several inherent difficulties exist in studying the transport behavior of GEMs in soil and subsurface environments. Detection of low microbial numbers or of stressed microbial populations is exceedingly difficult with traditional technology. In an effort to improve detection sensitivity, many improved methods of monitoring GEMs in the soil and subsurface are currently under development (Chaudhry et al. 1989). Beyond the difficulties of making accurate measurements of microorganisms to determine their spatial and temporal situation in the soil and subsurface environment, lies the need to ascertain the dynamic relationships between indigenous populations of microorganisms and how they may interact with a released GEM. Also, research strategies have not adequately addressed methods to predict the potential interactions between GEMs and natural microorganisms. These issues must be addressed if environmental risk assessment is to be valuable. There is clearly a need for focused research on the survival and transport of GEMs in these environments.

Small bowel obstruction due to enterolith: CT appearance.

A case of small bowel obstruction due to an enterolith presented on CT with a laminated appearance mimicking intussusception.

Conversion of indole to oxindole under methanogenic conditions.

When indole was incubated under methanogenic conditions with an inoculum of sewage sludge, the chemical was metabolized with 10 days and temporary formation of an intermediate was observed. The metabolite was isolated by thin-layer chromatography and determined to be 1,3-dihydro-2H-indol-2one (oxindole) by UV spectroscopy (lambdaMAX, 247 nm) and mass spectrometry (m/z, 133). The methane produced (net amount) indicated nearly complete mineralization of indole.

Pulmonary vascular occlusion and fibrosing mediastinitis.

Patients with fibrosing mediastinitis causing obstruction of pulmonary veins and arteries may present with many of the historic, physical, and laboratory findings of patients with pulmonary hypertension due to chronic thrombotic obstruction of major pulmonary arteries. Because the latter is subject to surgical correction, and the former is not, it is important to differentiate between the two and to be aware of the similarities in presentation. Three patients with pulmonary hypertension due to compression of pulmonary veins and the right pulmonary artery by fibrosing mediastinitis are presented who illustrate these points. A review of the literature documents other instances in which vascular involvement due to fibrosing mediastinitis has mimicked other types of pulmonary hypertension.

A trial use of some of Reitan's neuropsychological tests to assess mild organic complications in psychiatric patients.

Several testing procedures borrowed from Reitan's extensive investigations of impairment in brain function were employed in the present study (Tactual Performance Test, Trail Making Test, Seashore Rhythm Test, Speech Sounds Perception Test, Finger Oscillation Test). These tests were administer to three groups of Ss matched for age, education, and sex distribution. All Ss were 40 years of age or older. The groups were: hospitalized psychiatric patients suspected by their psychiatrists of some degree of organic impairment; hospitalized psychiatric patients not suspected of any organic impairment; and nonhospitalized, apparently normally functioning control Ss. Four months after the beginning of the study, the psychiatrists reevaluated and reclassified the patient Ss and formed new groups of those suspected and not suspected of organic impairment. A comparison of group means that used the original S groups showed that three of nine test scores were nondiscriminating, while the remaining six discriminated the control Ss from the patients, but not the two patient groups from each other. A similar comparison that used the revised patient groups formed from the psychiatrists' re-evaluations after an additional 4 months of observation yielded four test scores that discriminated successfully between the two patient groups: Tactual Performance Test, total time; Trail Making Test, Part A and Part B; and Finger Oscillation Test, right hand. These four test scores predicted the later classification of the patients more accurately than did the psychiatrists' own original evaluations, which would be in keeping with the general function of diagnostic testing, i.e., to provide initial information about patients beyond that which can be obtained from initial psychiatric examination.