An assessment of the toxicity of some pesticides and their metabolites affecting a natural aquatic environment using the Microtox™ system

Abstract

The conservation and preservation of aquatic ecosystems is of utmost importance due to the high diversity and density of species and their complex food network. The evaluation of the potential adverse environmental impact caused by pesticides entering water bodies is an important parameter in aquatic toxicity. The toxicity of the insecticide, Fenitrothion and two of its metabolites, 3-methyl-4 nitrophenol and 3-methyl-4-nitroanisole, and of the herbicides Thiobencarb and Molinate, commonly used in rice fields in Valencia near the protected area of lake Albufera, has been tested by using the Microtox™ system. The 15 min EC50 values obtained with the marine luminescent bacterium Vibrio fischeri showed that the Thiobencarb was the most toxic of the three tested pesticides with an EC50 value of 0.03 mg/l. The EC50 values of the first two steps of the Fenitrothion hydrolysis indicated that while the first metabolite, 3-methyl-4-nitrophenol, was as toxic as its parent compound, a decreased toxicity was observed for the second metabolite, 3-methyl-4-nitroanisole. In order to analyze the toxic effects of pesticides in complex mixtures the EC50 values of Fenitrothion, Molinate and Thiobencarb as pure substances and their mixtures were compared. The impact of the pesticides in the natural ecosystem was also studied and a protective effect of lake water was observed.

Photodegradation kinetics of fenitrothion in various aqueous media and its effect on steroid hormones biosynthesis

“…The selection of these photoproducts was, firstly, based on the fact that they possess a significant toxicity to the aquatic environment, sometimes more than the fenitrothion (Eto, 1974;Amoros et al, 2000). Secondly, they are considered to be the most common photoproducts of fenitrothion, formed under both photolysis and photocatalytic degradation (Durand et al, 1992(Durand et al, , 1994Kerzhentsev et al, 1996;Castillo et al, 1997).…”

“…Furthermore, fenitrothion is known for its acute toxicity toward nontarget organisms and, after application, different types of degradations affect this pesticide, such as photolysis, hydrolysis and biological degradation (Lacorte and Barcelo, 1994). In addition, for fenitrothion, many of the phototransformation products, such as fenitrooxon and 3-methyl-4-nitrophenol, may be even more toxic than the parent compound (Eto, 1974;Amoros et al, 2000). Therefore, it becomes necessary to monitor the behavior as well as the presence of fenitrothion and its photoproducts in the environment (Lacorte and Barcelo, 1994).…”

Demystifying Chronic Kidney Disease of Unknown Etiology (CKDu): Computational Interaction Analysis of Pesticides and Metabolites with Vital Renal Enzymes

“…Ethylenethiourea is the metabolite formed form dithiocarbamates, and it has been proven that ethylenethiourea can induce thyroid cancer and modify thyroid hormones [38]. Amorós et al [39] reported that the metabolites of Fenitrothion are more toxic than the original compound. Quinalphos metabolite 2-hydroxyquinoline (HQ) has been shown to photo catalytically destroy antioxidant vitamins and biogenic amines in vitro.…”

Ecotoxicological evaluation of sewage sludge using bioluminescent marine bacteria and rotifer

“…The bioassay is based on inhibition of luminescence of the bacterium detecting these changes in light output (SDI 2002). This method has been widely used for ecotoxicology assays since 1979 (Boluda et al 2002;Cotou et al 2002;Bogaerts et al 2001;Choi and Meier 2001;Doherty 2001;Amoros et. al.…”