Diazinon recommendations

Diazinon adversely affects survival of developing mallard embryos when the eggshell surface is subjected for 30 seconds to concentrations 25 to 34 times higher than recommended field application rates. Mortality patterns were similar for solutions applied in water or in oil (Table 16.3). 

Enthusiasm for chemicals by the industry and the public, however, went largely unabated, and indeed the number and range of available and recommended chemicals began to multiply in this period, with specialized formulations targeted at specific weed and insect problems. Aldrin, carbaryl, diazinon, Dicamba, meta-chlorophenylpiperazine (MCPP), chlorpyrifos, Carbaryl, Pyrethrum, and Dacthal (DCPA) all found their way to consumer markets in the next few years, capped by the arrival of glyphosate (known most commonly by its trade name Roundup ). Despite setbacks (as in the case of DDT), the chemical approach to lawn care has become normal and widespread, with more households using these chemicals every year. 

Acute- and chronic-duration inhalation exposure MRLs for diazinon were not derived because of a lack of suitable studies in the literature. Since diazinon is not volatile, inhalation exposure near toxic waste sites is probably less likely than oral or dermal exposure. However, the potential risk of adverse health effects from inhalation exposure to diazinon cannot be assessed without information on the levels actually present in the air around the site. The MRL level of 0.009 mg diazinon/m3 should be protective for individuals living near waste sites. NIOSH has recommended a Permissible Exposure Level (PEL) of 0.1 mg diazinon/m3 to protect the health of individuals who regularly use diazinon in their work the MRL level of... 

NIOSH recommends that the occupational exposure level not exceed 100 pg/m3 for a 10-hour TWA workday (NIOSH 1992). In addition, the American Conference of Governmental Industrial Hygienists has recommended a time-weighted average threshold limit value (TWA-TLV) of 100 pg/m3 for occupational exposure to diazinon (ACGIH 1986). 

This is the only available well conducted intermediate-duration inhalation study for diazinon. In an acute-duration study in which rats were exposed to 2,300 mg/m3 diazinon for four hours (Holbert 1989), mild signs of organophosphate toxicity were noted (nasal discharge, salivation). NIOSH recommends an occupational exposure level of 0.1 mg/m3, approximately 100-fold higher than the MRL. 

ISO 11246 recommends using this method for the extraction of a wide variety of herbicides. A study carried out on soils using the shaking method with acetate ethyl obtained recoveries of 85% for diazinon and 88% for chlorpyriphos (Table 23.7). 

The fate of diazinon in submerged soil and paddy water with emphasis on its metabolism by microorganisms is reviewed. The first part of this paper deals with the fate of diazinon in submerged soil which has never been exposed to diazinon. The detailed experimental procedures and results of this phase have been reported elsewhere (2,12). The second part will center largely on enhanced diazinon metabolism in submerged soil and paddy water following repeated applications at levels and intervals recommended for rice pest control. 

The persistence of diazinon in soil from a rice field that had never been exposed to diazinon before and in soil from a previously treated field was studied under flooded conditions. The treated fields received granular applications of diazinon (17) at rates and intervals recommended for rice pest control viz, 2 kilogram/ha active ingredient every 20 days. Soils (Maahas clay, pH 6.6) were collected from three treated and three untreated fields 12 days after the third application. Soils were air-dried and screened (2mm) 20 gram samples of these soils were placed in test tubes and flooded with 25 ml of aqueous diazinon solution. The insecticide residues from the soils incubated at 30 °C were extracted periodically with hexane-acetone (2) and analyzed in a gas chromatograph fitted with a cesium bromide detector as described earlier (18). 

Aquatic organisms were impacted by diazinon water concentrations between 0.3 and 1.2 jig/L effects included lowered emergence and elevated drift of stream insects (0.3ttg/L), reduced fecundity of marine minnows (0.47 ixg/L), accumulations in freshwater teleosts (0.55 p,g/L), and daphnid immobilization (1.0p.g/L) and death (1.2p,g/L). These comparatively low levels are of concern because transient peak water concentrations of 4.0-200.0 ttg diazinon/L have been recorded near diazinon sheep-dipping sites in England, and 36.8 ttg/L in the Sacramento-San Joaquin River, California. For protection of sensitive aquatic organisms, a water diazinon level should not exceed 0.08 p-g/L. This value represents a safety factor of about 4 over the lowest recorded adverse effect level of 0.3 pg/L. For protection of freshwater aquatic life, an average 4-day concentration of 0.04 pg diazinon/L is recommended, provided that this value is... 

At recommended treatment levels, diazinon-related kills have been noted for songbirds, honeybees, and especially waterfowl that consume diazinon-treated grass moreover, incidents involving agricultural applications may be underreported. Accidental deaths through misapplication of diazinon have also been recorded in domestic poultry, monkeys, and humans. It has been suggested, but not yet ver-ifled, that wildlife partially disabled in the field... 

Diazinon and trichlorfon (Dylox 50% WP or Proxol 80 SP) are two insecticides frequently used by the commercial lawn industry because of their relatively low level of acute toxicity. Recommended rates for insect control may vary. Diazinon may be applied at 1 to 3 oz. active ingredient per 1,000 sq. ft. Trichlorfon is also used for control of insects at 2 to 3 oz. active ingredient per 1,000 sq. ft. Lawn insects controlled include chinch bugs, sod webworms, cut worms, army worms, and grubs. 

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