nitrophenols and 2-4-5-trichlorophenol

With thousands of organic chemicals released every day into our environment, Europe and other continents are confronted with increased risk of health and environmental problems. Even if a strict regulation such as REgistration, Authorization and restriction of CHemicals (REACH) is imposed and followed by industry to ensure that they prove the harmlessness of their substances, not all testing procedures are designed to cope with the complexity of the environment. This is especially true for the evaluation of persistence through biodegradability assessment guidelines. Our new approach has been to adapt "in the lab" biodegradability assessment to the environmental conditions and model the probability for a biodegradation test to be positive in the form of a logistic function of both the temperature and the viable cell density. Here, a proof of this new concept is proposed with the establishment of tri-dimensional biodegradability profiles of six chemicals (sodium benzoate, 4-nitrophenol, diethylene glycol, 2,4,5-trichlorophenol, atrazine, and glyphosate) between 4 to 30 °C and 10(4) to 10(8) cells ml(-1) as can be found in environmental compartments in time and space. The results show a significant increase of the predictive power of existing screening lab-scale tests designed for soluble substances. This strategy can be complementary to those current testing strategies with the creation of new indicators to quantify environmental persistence using lab-scale tests.

Topics: Atrazine; Bacteria; Biodegradation, Environmental; Chlorophenols; Ethylene Glycols; Glycine; Glyphosate; Laboratories; Models, Theoretical; Nitrophenols; Sodium Benzoate

Residues of toxic chemicals in human tissues and fluids can be important indicators of exposure. Urine collected from a subsample of the second National Health and Nutrition Examination Survey was analyzed for organochlorine, organophosphorus, and chlorophenoxy pesticides or their metabolites. Urine concentration was also measured. The most frequently occurring residue in urine was pentachlorophenol (PCP), found in quantifiable concentrations in 71.6% of the general population with an estimated geometric mean level of 6.3 ng/ml. Percent quantifiable levels of PCP were found to be highest among males. Quantifiable concentrations of 3,5,6-trichloro-2-pyridinol (5.8%), 2,4,5-trichlorophenol (3.4%), para-nitrophenol (2.4%), dicamba (1.4%), malathion dicarboxylic acid (0.5%), malathion alpha-monocarboxylic acid (1.1%), and 2,4-D (0.3%) were found, but at much lower frequencies. No quantifiable levels of 2,4,5-T or silvex were found. Preliminary analyses showed an apparent relationship between residue concentration and two measures of urine concentration (osmolality and creatinine). A large segment of the general population of the United States experienced exposure to certain pesticides, including some considered biodegradable, during the years 1976-1980.

Topics: 2,4-Dichlorophenoxyacetic Acid; Adolescent; Adult; Age Factors; Aged; Chlorophenols; Dicamba; Female; Herbicides; Humans; Malathion; Male; Middle Aged; Nitrophenols; Osmolar Concentration; Pentachlorophenol; Pesticide Residues; Pyridones; Sex Factors; Socioeconomic Factors

Uptake rates of total 14C in fathead minnows (Pimephales promelas) exposed to sublethal concentrations of radiolabeled test compounds followed the order: phenol > 2,4,5-trichlorophenol > p-nitrophenol. Mean whole body 14C concentration factors were 15,800, 1,850, and 180 for phenol, 2,4,5-trichlorophenol, and p-nitrophenol exposures, respectively. Only minor amounts of tissue 14C was parent compound after 28 days of exposure in fish exposed to phenol and p-nitrophenol, while 78.6% of the 14C was parent compound in 2,4,5-trichlorophenol exposed fish. Tissue 14C in fish exposed to 2,4,5-trichlorophenol was eliminated at a faster rate than in fish exposed to phenol or p-nitrophenol. Observed mean 14C depuration half-lives for lower and higher exposures combined were 387, 150, and 12 hours for phenol, p-nitrophenol, and 2,4,5-trichlorophenol, respectively. Parent compound comprised 1.5, 2.7, and 0.7% of total 14C for phenol, 2,4,5-trichlorophenol, and p-nitrophenol, respectively, after 28 days of depuration. The percentage of acetone-unextractable 14C increased from the end of uptake to the end of depuration for phenol and 2,4,5-trichlorophenol, and decreased slightly for p-nitrophenol. 14C contribution from polar metabolites increased relative to total 14C during the depuration phase for 2,4,5-trichlorophenol and p-nitrophenol.

Topics: Animals; Chlorophenols; Fishes; Kinetics; Lipids; Models, Biological; Nitrophenols; Phenol; Phenols; Water