SETAC Globe - Environmental Quality Through Science
 
  12 May 2011
Volume 12 Issue 5
 

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ET&C Journal Article Spotlight—Sublethal Genotoxicity and Cell Alterations by Organophosphorus Pesticides in MCF-7 Cells: Implications for Environmentally Relevant Concentrations

Jane Parkin Kullmann (Haley & Aldrich, Inc.)

Organophosphorus pesticides (OPPs) have been used as commercial insecticides since the early 1950s. In the 1970s they succeeded organochlorine pesticides (OCPs) as the most widely used commercial insecticides, in part because their lability made them an attractive alternative to the persistent, bioaccumulative OCPs.1 The fact, though, that OPPs more readily undergo chemical transformations in the environment raises questions about OPP degradates.

Environmental Toxicology and Chemistry has been active in publishing research on the potential for OPP degradates, and residual OPPs, to harm non-target organisms at environmentally relevant doses. A very recent example is a paper published in the March issue of ET&C on cellular effects of OPPs (Ukpebor et al. 2011).

Ukpebor et al. investigated suspected effects of in vivo exposure to sublethal OPP concentrations. Their objectives were to better characterize dose-response relationships and understand the specific non-target effects that could be attributed to exposures at levels present in aquatic environments other than where the OPPs were deliberately applied. They used genotoxic and gene expression assays to examine cellular biochemical changes following exposures of mammalian MCF-7 cells to sublethal doses of fenitrothion, diazinon, and two aqueous degradation product of diazinon: 2-isopropyl-6-methyl-4-pyrimidinol (IMP). They report observing statistically significant biochemical changes after exposure to these OPPs and degradates, including elevated micronucleus formation and elevated activity of gene expression for the B-cell leukemia/lymphoma-2 (BCL-2) and cytochrome P450 isoenzyme (CYP1A1) enzymes. They also report observing other biochemical effects related to alterations to lipid, protein, and DNA/RNA in the cells.

The effects on micronucleus formation by OPPs was compared to those characteristic of benzo(a)pyrene [B(a)P], a known genotoxin, and was used as a control for this endpoint. It is notable that a similar degree of effect was observed at each dose of the OPPs, indicating a potentially flat dose-response relationship at these lower dosage levels. One hypothesis presented by the authors to explain this result was that the micronucleus-forming effects observed at low doses are characterized by endocrine disruptor mechanisms that might not follow a classic dose–response relationship such as the one observed for B(a)P, and instead represent a threshold effect where the increase in micronucleus formation is constant rather than dependent on dose. The authors also pointed out that these chromosomal effects, while representing some level of toxicity, did not lead to significant levels of cell death, so that the overall effect on the cells does not constitute a cytotoxic endpoint.

Ukpebor et al. conclude by identifying possibilities for the future study of OPPs in this lower dose regime. They suggest the need for additional work to refine our understanding of the modes of action and dose-response relationships for the observed effects, and also going beyond assays of general cell types to using the types of cells that would correspond to biota that might be exposed to these chemicals in the aquatic environment.

SETAC and its members have contributed greatly to the scientific literature on pesticide ecotoxicity, environmental chemistry, environmental fate, and ecological risk assessment. A title and keyword search of Wiley’s Online Library (available on the SETAC Journals web page) yields 428 ET&C and 28 IEAM pesticide papers. In addition SETAC has published at least ten books on pesticides. SETAC’s pesticide publications in just the last two years include at least 67 papers and six books. Here are the pesticide papers that SETAC has published so far in 2011, and its books from the last two years:

SETAC Pesticide Papers, 2011 Year-To-Date

Anderson B, Phillips B, Hunt J, Largay B, Shihadeh R, Tjeerdema R. Pesticide and toxicity reduction using an integrated vegetated treatment system. ET&C 30(5).

Bartelt-Hunt SL, Snow DD, Damon-Powell T, Brown DL, Prasai G, Schwarz M, Kolok AS. Quantitative evaluation of laboratory uptake rates for pesticides, pharmaceuticals, and steroid hormones using POCIS. ET&C 30(5).

Bradford DF, Knapp RA, Sparling DW, Nash MS, Stanley KA, Tallent-Halsell NG, McConnell LL and Simonich SM. Pesticide distributions and population declines of California, USA, alpine frogs, Rana muscosa and Rana sierrae. ET&C 30(3).

Chauzat M-P, Martel A-C, Cougoule N, Porta P, Lachaize J, Zeggane S, Aubert M, Carpentier P, Faucon JP. An assessment of honeybee colony matrices, Apis mellifera (Hymenoptera: Apidae) to monitor pesticide presence in continental France. ET&C 30(1).

Distel CA, Boone MD. Pesticide has asymmetric effects on two tadpole species across density gradient. ET&C 30(3).

Genualdi, SA, Hageman KT, Ackerman LK, Usenko S, Massey Simonich SL. Sources and fate of chiral organochlorine pesticides in western U.S. National Park ecosystems. ET&C 30(5).

Guy M, Singh L, Mineau P. Using field data to assess the effects of pesticides on Crustacea in freshwater aquatic ecosystems and verifying the level of protection provided by water quality guidelines. IEAM 7(2).

Hartwell SI. Chesapeake Bay watershed pesticide use declines but toxicity increases. ET&C 30(5).

Hoang TC, Pryor RL, Rand GM, Frakes RA. Use of butterflies as nontarget insect test species and the acute toxicity and hazard of mosquito control insecticides. ET&C 30(4).

Ioriatti C, Agnello AM, Martini F, Kovach J. Evaluation of the environmental impact of apple pest control strategies using pesticide risk indicators IEAM 7(2).

Jones DK, Hammond JI, Relyea RA. Competitive stress can make the herbicide Roundup® more deadly to larval amphibians. ET&C 30(2).

Kurt-Karakus PB, Teixeira C, Small J, Muir D, Bidleman TF. Current-use pesticides in Ontario, Canada, inland lakes, precipitation, air and zooplankton samples. ET&C 30(5).

Luttik, R, A. Hart, W Roelofs, P Craig, P Mineau. Variation in the level of protection afforded to birds and crustaceans exposed to different pesticides under standard risk assessment procedures. IEAM 7(2).

Mineau P. Barking up the wrong perch: Why we should stop ignoring non dietary routes of pesticide exposure in birds. IEAM 7(2).

Moore MT, Denton DL, Cooper CM, Wrysinski J, Miller JL, Werner I, Horner G, Crane D, Holcomb DB, Huddleston III GM. Use of vegetated agricultural drainage ditches to decrease pesticide transport from tomato and alfalfa fields in California, USA. ET&C 30(5).

Passeport E, Benoit P, Bergheaud V, Coquet Y, Tournebize J. Selected pesticides adsorption and desorption in substrates from artificial wetland and forest buffer. ET&C 30(5)

Sanchez-Bayo F, Hyne RV. Comparison of environmental risks of pesticides between tropical and non-tropical regions. IEAM 7(2).

Story P, Hooper MJ, Astheimer LB, Buttemer WA. Acute oral toxicity of the organophosphorus pesticide fenitrothion to fat-tailed and stripe-faced dunnarts and its relevance for pesticide risk assessments in Australia. ET&C 30(5).

Thoma, KA, Hand LH. Assessing the potential for algae and macrophytes to degrade crop protection products in aquatic ecosystems. ET&C 30(3).

Ukpebor J, Llabjani V, Martin FL, Halsall JC. Sublethal genotoxicity and cell alterations by organophosphorus pesticides in MCF-7 cells: implications for environmentally relevant concentrations. ET&C 30(3).

Zafar, MI, Van Wijngaarden RPA, Roessink I, Van den Brink PJ. Effects of time-variable exposure regimes of the insecticide chlorpyrifos on freshwater invertebrate communities in microcosms. ET&C 30(5).

Zhang, B-Z, Yu H-Y, You J, Zeng EY. Input pathways of organochlorine pesticides to typical freshwater cultured fish ponds of South China: hints for pollution control. ET&C 30(5).

SETAC Pesticide Books, 2009-2011

Brock TCM et al. (eds). 2009. Linking Aquatic Exposure and Effects: Risk Assessment of Pesticides.

Maltby L et al. (eds). 2009. Aquatic Macrophyte Risk Assessment for Pesticides.

Schäffer A et al. (eds), 2010. Semi-Field Methods for the Environmental Risk Assessment of Pesticides in Soil.

Sparling DW et al. (eds). 2010. Ecotoxicology of Amphibians and Reptiles. Second Edition.

Thorbek P et al. (eds). 2009. Ecological Models for Regulatory Risk Assessments of Pesticides: Developing a Strategy for the Future.

Warren-Hicks WJ, Hart A (eds). 2010. Application of Uncertainty Analysis to Ecological Risks of Pesticides.

Author contact information: jkullmann@haleyaldrich.com

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