Appendix 2 Open Literature Review Summaries for Malathion
Description of Use in Document
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- Primary Reviewer
- Purpose of Review (Note: DP Barcode required for Quantitative studies)
- Results (for Chlorpyrifos and Malathion only) : Exposure to Single Chemicals
- Table 1. Effects to Soybeans from Exposure to Chlorpyrifos and Malathion.
- % FRESH WEIGHT REDUCTION
- Description of Use in Document (QUAL, QUAN, INV)
- Limitations of Study
- Open Literature Review Summary Chemical Name
- Purpose of Review (DP Barcode required for Quantitative studies)
Description of Use in Document: Valid for arrays (qualitative) Rationale for Use: Based on limitations below Limitations of Study: [Major] There is uncertainty in how to interpret the results of this study in the context of an adverse effect given the relative increase in AChE (approximate 18% increase) and then 10% decrease in AChE, respectively, over a relatively long study duration (1 year). Additionally, the inconsistencies in the reporting between text and figures/tables increases uncertainty in the reliability of results. There are inconsistencies in the reporting of significance between the text and corresponding tables/figures. While there were no effects on body weight and only one mortality observed for malathion, the study did not report if other sublethal effects (e.g., behavior) were observed. Study was conducted with formulation. Reviewer assumed reported doses were adjusted for purity, but this is not certain. Also, as formulation was obtained outside of U.S., uncertain how it may be reflective of formulations in United States. Primary Reviewer: Amy Blankinship, ERB6 Secondary Reviewer: Elizabeth Donovan, ERB6 Open Literature Review Summary Chemical Name: Chlorpyrifos and Malathion CAS No: 2921-88-2 PC Code: 059101, 057701 ECOTOX Record Number and Citation: E068422 Ahrens, W.H. 1990. Enhancement of soybean (Glycine max) injury and weed control by thifensulfuron-insecticide mixtures. Weed Technology, 4(3): 524 – 528. Purpose of Review (Note: DP Barcode required for Quantitative studies): Chlorpyrifos ESA pilot (Registration Review) Date of Review: 01/07/15 Summary of Study Findings: Soybeans (Glycine max) were exposed to single chemicals (thifensulfuron, carbaryl, chlorpyrifos, malathion, and methomyl) and combinations of these insecticides with thifensulfuron (an herbicide). Pesticidal combinations were also tested with kochia and yellow foxtail (species not specified). Commercial pesticide formulations were used, but the formulations or percent a.i. were not specified. A nonionic surfactant [X-77; 0.25% (v/v)] was added to all treatments. Treatments were applied using a moving nozzle pot sprayer. Exposure to single chemicals were at concentrations of 0 (control), 140, 280, and 560 g/ha (0, 0.125, 0.25, and 0.5 lb a.i./acre, respectively). There were three plants per 0.5-L plastic pots. Soybeans were treated at the unifoliolate stage and were harvested 17 days after treatment. At harvest, injury was estimated visually (0% = no injury to 100% = complete necrosis). Fresh weight of shoots was determined after removal at soil level. The experiments were conducted in greenhouses from January to April. Temperatures during the test ranged from 22o to 26o C. Experiments were arranged as a randomized complete block design having four of five replicates and each experiment was repeated. Differences between means were determined using the least significant difference (0.05). Results (for Chlorpyrifos and Malathion only): Exposure to Single Chemicals: For chlorpyrifos and malathion, there were no statistically significant differences from control in percent injury at any concentration tested (see Table 1). For chlorpyrifos, there was a 7, 8, and 9% reduction in weight at the 0.125, 0.25, and 0.5 lb/acre concentrations, respectively. The differences were statistically significant from controls at the 0.25 and 0.5 lb/acre concentrations, resulting in NOAEC and LOAEC values of 0.125 lb/acre and 0.25 lb/acre, respectively, based on a reduction in weight. For malathion, there was a 5, 5, and 12% reduction in weight at the 0.125, 0.25, and 0.5 lb/acre concentrations, respectively. The difference was statistically significant from controls at the 0.5 lb/acre concentration, resulting in NOAEC and LOAEC values of 0.25 lb/acre and 0.5 lb/acre, respectively, based on a reduction in weight. Table 1. Effects to Soybeans from Exposure to Chlorpyrifos and Malathion.
* Statistically significantly different from the control Exposure to Mixtures: When the herbicide, thifensulfuron, was applied with chlorpyrifos or malathion to soybeans, kochia and yellow foxtail (at varying concentrations), chlorpyrifos and malathion showed signs of synergism with soybeans and yellow foxtail (based on injury and %weight reduction) when the actual results were compared to expected results (no synergy). Potential synergistic effects were not noted for kochia and these chemical mixtures. Description of Use in Document (QUAL, QUAN, INV): Results for single chemical (chlorpyrifos and malathion) and single test species = QUAN; results for mixtures = QUAL Rationale for Use: This review was conducted because the reported chlorpyrifos NOAEC value of 0.125 lb/A for reduction in weight currently represents the most sensitive NOAEC value for terrestrial plants and chlorpyrifos. Limitations of Study: The purity of the chemicals used in the study were not reported. Raw data were not provided; therefore, the statistics could not be verified. Primary Reviewer: Melissa Panger, Ph.D. Secondary Reviewer: Elizabeth Donovan, M.S [Additional comment: given the lack of purity information for malathion, there is uncertainty in the impurity profile and the results should be valid for arrays only (qualitative), A. Blankinship, December 7, 2016] Open Literature Review Summary Chemical Name: Malathion, obtained from Cyanamid India Ltd, Bombay CAS No: Not reported PC Code: 057701 ECOTOX Record Number and Citation: 025359. Chakraborti, S., N. Sarkar, P. K. Sengupta, and S.K. Banerjee. 1982. Biochemical Studies of Some Membrane Bound Hydrolases in Malathion Treated Germinating Seeds of Vigna sinensis (L): Effect of Plant Growth Hormone Supplementation. Indian Journal of Experimental Biology. 20: p 850-855. Purpose of Review (DP Barcode required for Quantitative studies): Malathion ESA pilot (Registration Review) Date of Review: February 5, 2015 Summary of Study Findings: Cowpea (Vigna sinensis) seeds were surface sterilized in 0.1% mercuric chloride followed by soaking in deionized water for six hours. Seed coats were removed and dehulled seeds were added to petri dishes containing malathion (purity not specified) at concentrations of 0, 50, 100, 200, and 400 ppm. Additional petri dishes spiked with one of three plant hormones [indole-3-acetic acid (IAA), gibberellic acid (GA3), or Kinetin] were included in the study design at each malathion exposure concentration, plus plant hormone controls. A total of 20 different petri dish treatments were included in the study design, although it appears that these different treatments were not replicated; however, the experiment was repeated six times and the reported data are means ± SD of these trials. Seeds in the experimental plates were allowed to germinate for 72 hours at 25 oC. After 72 hours, the roots from each plate were removed and ground using a mortar and pestle. The homogenate was processed and the plasma membrane fraction of the roots was isolated. Seedling growth and respiration in the different treatments were graphed, although the underlying growth and respiration data for the plots were not reported. From the graph (Figure 2 on page 852), growth appears to have been inhibited by 12, 25, and 50% at the 100, 200, and 400 ppm treatments, respectively. In the same graph, respiration appears to have been inhibited by 22, 48, and 78% at the 100, 200, and 400 ppm treatments, respectively. Data tables for treatment responses were only provided for seven plasma membrane analyses (acid phosphatase, acid pyrophosphatase, alkaline pyrophosphatase, IDPase, ATPase, mg phospholipid, and mg sterol). Response data for the 100, 200, and 400 ppm treatments for each of the seven plasma membrane parameters evaluated were found to be statistically significant (statistical methods not described; see limitations section). The study authors discuss the association of alkaline inorganic pyrophosphatase with anabolic processes and acid inorganic pyrophosphatase with catabolic processes, leading the study authors to conclude that the significant, dose-dependent increase in acid inorganic pyrophosphatase in the 100, 200, and 400 ppm treatments compared to the control is a marker of reduced seedling growth. Figure 2. Effect of malathion and/or plant hormones on seedling growth and respiration. 
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