V. Zitko

Effects of excitotoxins on free radical indices in mouse brain

Excitotoxins and free radicals individually have been implicated in several neurological disorders including those associated with aging. We observed that systemically administered domoic acid enhanced mouse brain superoxide dismutase activity with either an associated decrease or no change in mouse brain lipid peroxidation. These findings reflect a state of adequately compensated oxidative stress induced by excitotoxins. In homogenates containing disrupted cells from various regions of mouse brain, however, kainic acid produced a 2 to 5-fold increase in lipid peroxidation. This suggests that excitotoxins cause lipid peroxidation possibly by acting at intracellular loci which become more accessible following disruption of cells in vitro and by extrapolation, possibly in vivo due to cellular permeability changes during the edematous stage of ischemic and other related neuropathological conditions.

Toxicity of pyrethoids to juvenile Atlantic salmon

ConclusionsPermethrin is extremely toxic to juvenile Atlantic salmon and has a lethal threshold of approximately 9 μg/ℓ. It is relatively much more persistent than pyrethrins and allethrin. Fish accumulate permethrin from water and the accumulation coefficient of 55 indicates an intermediate degree of accumulation under the used experimental conditions.

The lethality of the cypermethrin formulation Excis® to larval and post-larval stages of the American lobster (Homarus americanus)

The pesticide formulation Excis® (1% w/v cypermethrin) is currently registered for use in the State of Maine, USA to treat farmed salmon for infestations of the copepod parasites, Lepeophtheirus salmonis and Caligus elongatus (sea lice). In Canada, the product has yet to receive regulatory approval. We have determined the acute lethality of this product to the three larval stages and the first post-larval stage of American lobster (Homarus americanus), a species of significant economic importance in eastern Canada and the northeast United States. The 48-h LC50 (as cypermethrin) is: 0.18 μg/l for stage I, 0.12 μg/l for stage II, 0.06 μg/l for stage III, and 0.12 μg/l for stage IV (the first post-larval stage). The differences in sensitivity among the larval stages are not statistically significant. These data, when interpreted in conjunction with known physical oceanographic data and results of chemical dispersion studies, indicate that single anti-louse treatments are unlikely to result in lobster mortality. However, the sublethal effects of this product on lobsters and the consequences of repeated exposures have yet to be determined.

Prediction of biodegradability of organic chemicals by an artificial neural network

Abstract A commercial Artificial Neural Network (ANN) program was used to predict the biodegradability of organic chemicals. Good predictions were obtained for mono- and di-substituted benzenes. The predictions based on a more heterogeneous set of various organic chemicals were not as good, but the approach is promising and ANNs are easy to implement.

Isomer-specific detection of PAHs and pah metabolites in environmental matrices by Shpol'skii luminescence spectroscopy

Shpolskii Spectroscopy, a high-resolution low temperature molecular luminescence technique, was applied to the analysis of various complex environmental matrices to obtain isomer specific information on a wide range of polycyclic aromatic hydrocarbons (PAHs) and their derivatives. Using conventional lamp excitation and fluorescence and phosphorescence detection, parent priority PAHs, six-membered ring compounds (e. g. potent carcinogens, dibenzopyrenes), and methyl-substituted PAHs were determined in crude and purified lubricating oil sample, extracts of sediment, and muscle from finfish. In addition, detection of major PAH metabolites (hydroxy-substituted PAHs) in gall bladder of fish is demonstrated by applying conventional lamp and Laser Excited Shpolskii Spectroscopy (LESS).

Assessment of the significance of chemicals in sediments

Abstract The assessment of pollution by sediments is based on the sediments’ similarity to sediments of known toxicities. The similarity is judged from plots produced by principal component analysis (PCA).

“Shorthand” numbering of chlorobiphenyls

Abstract It is proposed to use numbers in base 16 (Hex) for an abbreviated designation of chlorobiphenyls. Values assigned to substituents in positions 2, 3, 4, and 5 are 1, 2, 4, and 8, respectively. These are added and expressed in Hex. Substitutions in positions 6 and 6′ are given values of 1 and 2. The designation is a three-digit number, the digits from left to right referring to the first ring, primed ring, and to substituents in the 6 positions, respectively. In the shorthand notation, BD1h stands for 2, 2′, 3, 4′, 5, 5′, 6-heptachlorobiphenyl (h indicates Hex).

“Shorthand” numbering of chlorinated dibenzodioxins (CDD) and dibenzofurans (CDF)

Abstract Numbers in base 16 (Hex) are used for an abbreviated designation of chlorine substitution in CDD and CDF. This “shorthand” requires two hexadecimal digits. A letter (“d” or “f”) may be used to distinguish between CDD and CDF. The digits describe the substitution patterns in positions 6,7,8,9, and 4,3,2,1, assigned values of 8,4,2, and 1, respectively. For example, 66d = 2,3,7,8-tetrachlorodibenzo-p-dioxin.

TLC detection of brominated flame retardants in styrofoam

Abstract To detect the title compounds, a sample of styrofoam is dissolved in toluene and polystyrene is precipitated by hexane. Brominated flame retardants remain in the supernatant, are separated by silica TLC with toluene — hexane 25:75, and visualized by silver nitrate. 1,2,5,6,9,10-Hexabromocyclododecane (HBCD) was the most frequently detected flame retardant. 1,2,5,6-Tetrabromocyclooctane (TBCO) and pentabromochlorocyclohexane (PBCC) were found in two samples. Brominated flame retardants were not detectable in styrofoam used in food packaging and in two recent samples of packaging and ‘cooler’ styrofoam.

Multivariate classification of chlorobiphenyls according to enzyme induction

Abstract The data of Parkinson et al. (2) are evaluated by principal component analysis and the positions of the chlorobiphenyls in the plane of the first two principal components are discussed in relation to the substitution patterns of the chlorobiphenyls.