| Ökotoxizitätsauszüge | /AQUATIC SPECIES/ The response of the water receptor of frogs was repressed by nitrophenol derivatives. The order of reversible inhibitory action of the derivatives was 2,4-dinitrophenol (I) > 2,5-dinitrophenol > 2,4,6-trinitrophenol > p-nitrophenol > 2,6-dinitrophenol > m-nitrophenol > o-nitrophenol./AQUATIC SPECIES/ A comparison was made between the predicted 96-hr guppy median lethal concn of 110 phenols based upon quant structure-activity relationship (QSAR) equations of J Saarikoski and M Viluksela (1982) and the data from 936 toxicity screening tests for these chems. Test data on up to 8 species of freshwater fishers were available per cmpd. Overall, the experimental toxicity data on these chem were consistent with the QSAR predictions. The 110 phenols occupy a considerably larger range of spanned substituent space than the QSAR training set. One cmpd, 4-aminophenol exhibited lethality at test concn of 35 times below that predicted. The increased fish toxicity of this cmpd is explained in terms of a proelectrophilic mol mechanism, in which the parent cmpd is metabolically oxidized to a para quinoid structure. The resulting electrophilic metabolite is susceptible to attack by nucleophilic moieties present in biological macromols leading to covalent bond formation and inhibition of biochem processes./AQUATIC SPECIES/ The 96-hr median lethal concn (LC50) of 21 substituted phenols (I, R= H, alkyl, Cl, or NO2R1= H, Cl, OH, methoxy, alkyl, or NO2n= 0-5m= 0 to 5-n) for the guppy (Poecilia reticulata) were detd at pH 6-8 and related to the lipohilicity defined as log P from the 1-octanol/water system, and to the DELTApKa value (pKa of phenol - pKa). Log P was the more important parameter and exhibited a good correlation with log (1/LC50) at all pH levels. The contribution of DELTApKa when introduced as a 2nd parameter into the regression equation was dependent on the pH of water: at pH 6, it was pos but turned neg as the pH was raised to 8. If the LC50 were correlated for ionization using an empirically formulated relation between toxicity and pH, the resulting regression equation could be used to predict the toxicity at any pH from 6 to 8. When corrected for ionization, log BCF (the bioconcn factor) of 8 phenols was highly correlated with log P but not with DELTApKa. The regression of log BCF on log P sufficed to explain the regression of toxicity on lipophilicity./AQUATIC SPECIES/ The effects of the uncoupling reagents 2,4- and 2,5-dinitrophenol (DNP) on the ontogenesis of herring (Culpea harengus) were investigated. Eggs of the Baltic spring and autumn spawning herring were artificially fertilized, attached to glass plates and incubated in 1-L aerated containers (14 to 16% water salinity) for 30, 48 or 55 hr prior to incubation in 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.05, 0.075 and 0.10 mM 2,4- or 2,5-DNP/l. The solution temperatures were maintained at about 10.8 and 11.8 °C for the spring and autumn spawners, respectively. The effects of the DNP concentrations on the embryonic development were determined by measuring the activity of the embryo, the heartbeat rate and the mutagenic and mortality rates. The rate of mortality was shown to be dependent on the age of the embryo at the start of exposure and on the concentration of the DNP. Exposure at 30 and 48 hr resulted in 100% mortality at 0.025 and 0.03 mM/l, respectively. When the embryos were first exposed at 55 hr, highest concentration (0.10 mM DNP/l) produced 92.6% mortality. DNP also increased the occurrence of malformations which were in the form of anophthalmy, symmetrical and unilateral microphthalmy, curled bodies and dedifferentiations.For more Ecotoxicity Excerpts (Complete) data for 2,5-Dinitrophenol (8 total), please visit the HSDB record page. |
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