The Metabolism of [14C] O,O-Diethyl O-(3,5,6-trichloro-2-pyridyl)phosphorothioate (Dursban) in Fish1

The anticipated kinetic behavior of different amounts or forms of a chemical in the environment can be studied by introducing the chemical into a laboratory ecosystem, collecting samples of the different components of the system at various times, and obtaining a sequence of concentrations of the chemical and/or its metabolites. Conventional compartmental models can be used to characterize this concentration-time data in order to better predict the distribution and ultimate fate of a chemical introduced into the environment, to provide a quantitative measure for helping assess the environmental impact of different chemicals, and to reduce the cost of expensive laboratory testing and field work. SCOPEMost progressive industrial companies are committed to exercising responsible care for all products both during manufacture and later in their use by the customer. This product stewardship concept makes it necessary to collect and interpret meaningful data to assess the environmental impact of each new or existing product so that appropriate steps can be taken to protect employee and public health as well as the environment as a whole. One method being pursued is to build laboratory ecosystems which simulate typical environmental conditions. Then the kinetic behavior of different amounts or form of chemical is examined by introducing it into the simulated ecosystem, collecting samples of the different components of the system at various times, and obtaining a sequence of concentrations or amounts of the chemical and/or its metabolites. Collection of kinetic data is a departure from the standard practice of determining the residue at one or at most two time periods remote from the exposure time. In this paper we show that a conventional compartmental analysis can be used to characterize this data. The parameters of the characterizing model make it possible to compare the potential environmental impact of different chemicals. The model itself makes it possible to predict the time distribution in the environment for different modes of exposure (for example, slow release, accidental spill, etc.) so that proper exposure levels and handling procedures can be determined even before environmental testing is initiated.Two major problems are associated with the use of compartmental models. The first is the development of plausible models for a particular ecosystem. This requires considerable background in the field from which the problem arises. Accumulated knowledge must provide some justification for the model selected and the parameters selected must have meaning in terms of known processes and the structure of the real system. The second problem is the socalled "inverse" of the first. That is, given one or more plausible models for an ecosystem, what data should be collected to decide which model is the most suitable and to obtain meaningful estimates of the model parameters. Recently developed model discrimination and nonlinear parameter estimation techniques are combined in an iterative computer-based model building proce...

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“…This tends to substantiate the data obtained by Smith et al (1966) ; who demonstrated a partitioning between the viscera and the meat.…”

supporting

confidence: 90%

Ecokinetics: A study of the fate and distribution of chemicals in laboratory ecosystems

1975

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“…[32] reported that residue levels of chlorpyrifos in surviving O. latipes at 48 hrs exposure were 727 to 1,143 times greater than the water concentrations. Similarly [35] reported rapid accumulation of radio labeled chlorpyrifos in C .auratus during the first 10 hrs of exposure, and the maximum levels were reached within 12 hrs. Though in the current investigation, bioaccumulation and bioconcentration studies was not undertaken, but our OVC and TMR had the lowest significant values in 24hrs exposure suggesting possibly that surviving fish was maximally intoxicated at this period due to maximum bioconcentration and bioaccumulation and AChE inhibition.…”

Section: Discussionmentioning

confidence: 70%

Investigation of acute toxicity of chlorpyrifos-ethyl on Clarias gariepinus – (Burchell, 1822) using some behavioural indices

Ogueji¹,

Usman²,

Auta³

2013

International Journal of Basic and Applied Sciences

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The impact of short-term exposure to waterborne chlorpyrifos-ethyl on Clarias gariepinus was evaluated through changes of selected behavioural parameters. Fish was exposed to 0.64 mg/l, 0.80 mg/l, 0.96 mg/l, 0.12 mg/l, 0.28 mg/l and control for 96h. The parameters measured were Opercular ventilation (OVC), Tail fin movement rate (TMR), Air gulping index (AGI) and Mortality. The main effects of concentration and duration on rates of tail fin movement rate of fish were highly significant (p<0.001). There was significant decrease (p<0.05) in the opercular ventilation of treated fish when compared with control. Also both the main effects of concentration and duration of exposure of chlorpyrifosethyl and the effect of their interactions on AGI were highly significant (p<0.001). Highest mortality was recorded from 1-12hrs period of exposure and the mortality at 12hrs was significantly (P<0.05) higher than the mortality recorded from 24hrs-96hrs periods. The acute toxicity of chlorpyrifos-ethyl elicited dose and duration dependent behavioural changes that led to mortality of fish. Behavioural changes were therefore proven to be more sensitive endpoints than mortality.

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“…Second, the monodealkylated metabolite, C2, was likely to be produced through a dealkylation process and its formation relatively minor (1.8%) compared to other metabolites. In addition, early studies reported that CPS or CPO undergo mono-or bidealkylation to produce C2 in the urine of human and catfish or TCP phosphate in the urine of rat [4,16,20,26]. Third, two glucuronide conjugates, the O-glucuronide of TCP (C5) and the S-glucuronide of chlorine-substituted CPS (C9), were found in either CPS or CPO treatment or CPS treatment alone, respectively.…”

Section: Human Liver Hepatocytesmentioning

confidence: 99%

Metabolism of chlorpyrifos and chlorpyrifos oxon by human hepatocytes*

Choi

Joo

Rose

et al. 2006

J Biochem & Molecular Tox

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The metabolism of chlorpyrifos (CPS) and chlorpyrifos oxon (CPO) by human hepatocytes and human liver S9 fractions was investigated using LC-MS/MS. Cytochrome P450 (CYP)-dependent and phase II-related products were determined following incubation with CPS and CPO. CYP-related products, 3,5,6-trichloro-2-pyridinol (TCP), diethyl thiophosphate, and dealkylated CPS, were found following CPS treatment and dealkylated CPO following CPO treatment. Diethyl phosphate was not identified because of its high polarity and lack of retention with the chromatographic conditions employed. Phase II-related conjugates, including O- and S-glucuronides as well as 11 GSH-derived metabolites, were identified in CPS-treated human hepatocytes, although the O-sulfate of TCP conjugate was found only when human liver S9 fractions were used as the enzyme source. O-Glucuronide of TCP was also identified in CPO-treated hepatocytes. CPS and CPO were identified using HPLC-UV after CPS metabolism by the human liver S9 fraction. However, CPO was not found following treatment of human hepatocytes with either CPS or CPO. These results suggest that human liver plays an important role in detoxification, rather than activation, of CPS.

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The Metabolism of [14C] O,O-Diethyl O-(3,5,6-trichloro-2-pyridyl)phosphorothioate (Dursban) in Fish1

Cited by 46 publications

References 0 publications

Ecokinetics: A study of the fate and distribution of chemicals in laboratory ecosystems

Ecokinetics: A study of the fate and distribution of chemicals in laboratory ecosystems

Investigation of acute toxicity of chlorpyrifos-ethyl on Clarias gariepinus – (Burchell, 1822) using some behavioural indices

Metabolism of chlorpyrifos and chlorpyrifos oxon by human hepatocytes*

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