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Gary M Rand

Publications and source records attributed to Gary M Rand.

5 recordsLinked to original sources
PubMed2004

Fate and effects of the insecticide-miticide chlorfenapyr in outdoor aquatic microcosms.

The concentrations of chlorfenapyr in water and sediment in a lentic pond following early and late applications in a Florida crop treatment program were predicted using PRZM and EXAMS modeling and incorporating 30 years of actual rainfall data. An outdoor microcosm study was also conducted to determine the fate of chlorfenapyr and its effects on zooplankton, macroinvertebrates, phytoplankton, and fish in a freshwater system under exposure conditions representing simulated surface runoff and/or spray drift. The microcosm design used a regression model with five treatments (i.e., 300 microg/L spray, 30 microg/L spray, 15 microg/L spray and 30 microg/L runoff, 1.2 microg/L spray and 2.5 microg/L runoff, 30 microg/L runoff) plus a control. Chlorfenapyr was applied as an aqueous suspension concentrate (36% a.i.) to six microcosm tanks (30.9 m3). The no-observed-effect-concentration (NOEC) for zooplankton was the water concentration produced from the combination 1.2 microg/L spray and 2.5 microg/L runoff treatment. The NOEC for bluegill sunfish was the water concentration produced from the 30 microg/L runoff, which was significantly higher than the exposure concentrations from the lowest combination treatment. Chlorfenapyr was more toxic via spray to the water than via an exposure simulating surface runoff. The 96-h time weighted average concentrations (TWAs) from the lowest joint treatment and the 30 microg/L runoff treatment in the microcosm study were similar to model-predicted water 96-h TWA concentrations from early and late applications. The toxicity data from laboratory and microcosm studies along with water exposure data indicate low hazard to zooplankton species in the water column. Although chlorfenapyr remained in sediment, TWAs concentrations from the microcosm study along with model-predicted concentrations indicate low hazard to benthic invertebrate species based on acute toxicity to amphipods in the laboratory. Results from this assessment indicate that with appropriate measures to mitigate spray drift to shallow water bodies, applications of chlorfenapyr do not present a hazard to aquatic organisms during labeled uses.

Animals↗
PubMed2004

South Florida ambient pesticide monitoring program.

The South Florida Water Management District is a state agency that manages surface and ground water quantity and quality in south Florida. Since 1984 surface water and sediment have been sampled for pesticides at various frequencies and locations in the District's 1400-mile system of canals. Based on monitoring data from 1992 to 2001 the most common pesticides detected in surface water samples were herbicide compounds, especially ametryn and atrazine, while DDE and DDD were the most frequently detected in sediment samples. Exceedances of state surface water quality standards occurred in certain basins for several insecticides including endosulfan. In addition, the concentrations of several ubiquitous organochlorine compounds in sediment were similar to or exceeded threshold effect levels based on a comparison to the NOAA screening quick reference tables (or SQuiRTs) for sediment.

Environmental Monitoring↗
PubMed2004

Sediment toxicity in the St. Lucie River Watershed and Everglades Agricultural Area.

DDD, DDE and ametryn were the most frequently detected pesticides in sediment in the St. Lucie River Watershed (SLR) and Everglades Agricultural Area (EAA). Concentrations of organochlorine compounds typically exceeded NOAA (SQuiRTs) TELs for freshwater sediment. Microtox BSPT EC50s from sediments in the SLR and EAA were lower than other sediment samples and reference controls. Single-species 10-day toxicity tests with Hyalella azteca and Chironomus tentans and whole sediment sample exposures from the SLR and EAA showed no effects on survival or growth of both species. However, in 28-day tests with H. azteca, survival was reduced at two sites compared to a reference control and a third sampling site. There were no correlations between contaminant concentrations, EC50s and toxicity test results.

Agriculture↗
PubMed2002

Hazard assessment of resmethrin: I. Effects and fate in aquatic systems.

A comparative aquatic hazard assessment of resmethrin was conducted to investigate the need for its restricted use classification by the US. EPA as an adult mosquito control agent. This paper describes the environmental fate and aquatic toxicity of resmethrin. The following paper compares resmethrin to the alternative insecticides. Environmental fate studies indicate that resmethrin has a short photolytic half-life in water (<1 h). Furthermore, it is immobile in soil and biodegradable (half-life = 36.5 d) under aerobic conditions. Laboratory studies with constant 48- to 96-h exposures show it is acutely toxic to fish and invertebrates in the 0.22-15.0 microg/L range. Daphnia magna, pink shrimp (Penaeus duorarum) and rainbow trout (Oncorhynchus mykiss) are the most sensitive and mollusks are the least sensitive species. Chronic laboratory studies indicate that the maximum acceptable toxicant concentrations (MATCs) for resmethrin and D. magna, Pimephales promelas, O. mykiss, and Cyprinodon variegatus are 0.58, 0.52, 0.43, and 10.3 microg/L, respectively. The acute-to-chronic ratios (1.1-7.3) for all species studied indicate that chronic toxicity will not be an issue for resmethrin. Furthermore, the characteristics of acute exposures (48- to 96-h) used in the laboratory will not occur under field conditions because of the short half-life of resmethrin in fresh- and salt-water.

Animals↗