Terry D. Spittler

Influence of salinity on atrazine toxicity to a Chesapeake Bay copepod (Eurytemora affinis) and fish (Cyprinodon variegatus)

The objective of this study was to determine the influence of a range of salinities (5%., 15%., and 25%.) on the acute toxicity of atrazine to nauplii of the copepodEurytemora affinis and larvae of the sheepshead minnow,Cyprinodon variegatus. Ninety-six-hour LC50 values for the copepod were 0.5 mg 1−1, 2.6 mg 1−1, and 13.2 mg 1−1 at salimities of 5%., 15%. and 25%. respectively. A comparison of LC50 values between adjacent salinities showed a statistical difference between 15%. and 25%. but not between 5%. and 15%.. Atrazine was more toxic toE. affinis at the lowest salinity. The 96-h LC50s for the sheepshead minnow were 16.2 mg 1−1, 2.3 mg 1−1, and 2.0 mg 1−1 at salinities of 5%., 15%., and 25%., respectively. There was a statistical difference between LC50 values at 5%. and 15%. but not between 15%. and 25%.. In contrast toE. affinis results, atrazine was more toxic toC. variegatus at the highest salinity. The toxicity data from these species suggest that development of estuarine water quality criteria is warranted.

Determination of carbaryl in honeybees and pollen by high-performance liquid chromatography

Abstract Fifty of seventy bee and pollen samples were found to contain methyl parathion and/or carbaryl. One-third of these were randomly analyzed for azinphos methyl; several were positive. Responsibility for bee kills is difficult to determine and cannot be assigned on the basis of suspicion and a positive confirmatory analysis; other possible causes must be exclused. A multi-residue scheme for the above, plus fenvalerate, is presentd. High-performance liquid chromatographic determination of carbaryl on a reversed-phase column (C 8 -RCSS) with detection by both UV and fluorescence is discussed. The advantages of the latter detection method in this application are illustrated.

Determination of benomyl and its metabolites by cation-exchange high-performance liquid chromatography

In the high-performance liquid chromatography determination of benomyl fungicide [methyl 1-(butyl carbomoyl)-2-benzimidazolecarbamate] quantitative conversion to the metabolite methyl 2-benzimidazolecarbamate (MCB) is effected by the addition of 0.25 M hydrochloric acid during the rotary evaporation at 50–60°C of the extraction solvents, methanol—ethyl acetate (1:9). This mild hydrolysis allows for the simultaneous determination of MBC and 2-aminobenzimidazole by cation-exchange chromatography in a variety of agricultural commodities, environmental samples, and worker exposure monitoring devices. The interferences usually occasioned by acid reflux hydrolysis are minimized. A Zipax SCX column, maintained at 60°C, was used with a mobile phase of 0.025 M tetramethylammonium nitrate—0.025 M nitric acid; and detection was by UV at 280 nm.

Determination of carbofuran and its metabolites

High-performance liquid chromatographic (HPLC) methods for the determination of carbofuran and its metabolites are described. Results obtained for carrot samples by HPLC are compared with those obtained using gas chromatography and nitrogen-specific detection for carbofuran and 3-hydroxy carbofuran and gas chromatography-mass spectrometry with selected ion monitoring for the determination of the three 7-phenol metabolites. The effect upon observed residue levels of conjugate formation by the 3-hydroxy and/or the 7-phenoxy groups of the four metabolites is demonstrated, and appropriate acid hydrolysis techniques are described. Variations in the HPLC parameters for different commodities are presented.

Managing lepidopteran pests in cabbage with herbicide-induced resistance, in combination with a pyrethroid insecticide

S‐ethyldipropylthiocarbamate (EPTC) applied as a soil treatment or over‐the‐top spray on cabbage plants (Brassica oleracea L.) caused the leaves to turn ‘glossy’ for as long as 30 days. EPTC‐induced glossy plants were damaged significantly less than untreated plants by diamondback moth, Plutella xylostella (L.), imported cabbage worm, Pieris rapae (L.), and cabbage looper, Trichoplusia ni (Hbn.). Reductions in damage were equivalent to those obtained from treatment with permethrin. When used in combination with permethrin, EPTC provided additive control of damage by these pests. Our calculations show EPTC‐induced resistance to be cost‐effective. This use of EPTC has several limitations, however. Younger plants (<9 leaves) were killed or injured by the herbicide. The growth of older plants was not affected, but plants did not become glossy for ca. 10 days after they were treated with EPTC. The crop must be protected with insecticides until the plants are mature enough to treat with EPTC, and until treated plants become glossy. In addition, since the glossy trait is only effective against first instar larvae, populations of later instars on glossy plants must be reduced with an application of insecticide. Finally, EPTC formulations are water‐soluble and can be washed away from the plants by heavy rains and irrigation, which may make this use of EPTC impractical in some situations. Where its use is practical, and the indicated precautions are taken, EPTC‐induced resistance could reduce dependence on chemical insecticides and reduce selection for insecticide resistance in diamondback moth.

The influence of salinity and sediment on the loss of atra8ine from the water column

Abstract Two experiments of 128 – 130 days duration were conducted to determine the influence of salinity and sediment type on the loss of atrazine from the water column. In the first experiment, atrazine did not exhibit a significant loss after 128 days in any of the test conditions (atrazine concentrations of 5–5000 μg/L and salinities of 5–35 ppt) prepared with autoclaved water. However, a 17% loss was reported after 128 days in an ambient estuarine condition of 13 ppt. In the second 130 d experiment, the loss of 50 μg/L atrazine from the water column was determined at salinities ranging from 5 to 25 ppt without sediment and with either sand or silt-clay sediment. Results after 130 days were no loss of atrazine in the water only test conditions at the various salinities; loss of atrazine in the water column was significant in both sediment conditions and type of sediment did not appear to influence the loss from the water column; atrazine adsorption to clay-silt sediment was approximately twice as high as sand and loss of atrazine in the water column of both sediment conditions appeared greater at the higher salinity (25 ppt) when compared to the lower salinity (5 ppt).

Extraneous Pesticide Exposure

Publisher Summary The greatest potential for exposure within the research and development phase is during pilot plant design and operations. Here, chemical reactions are scaled up, new technologies are tried, and larger quantities of toxic materials are present. Recognition of the dangers involved, as well as government and industrial regulations mandating safety precautions, reduces this potential to within acceptable limits. The same procedures generally reduce the potential exposure for manufacturing workers. Although accidents and carelessness within both the research and development and manufacturing phases may result in some dangerous exposure situations, the overall potential is low. Formulators, on the other hand, may possess a fair potential for significant exposure. Although most formulators operate highly automated plants with remote handling and filling facilities, some, especially the smaller customer specialty formulators, by necessity operate under more hazardous conditions. For example, those involved in the local mixing of fertilizers and pesticides may run the risk of increased exposure.