Dust formulations

Indirect evidence indicates that dermal absorption occurs in animals. Calves dusted with a 4% dust formulation of endosulfan had neurological symptoms (tremors, twitching, convulsions) and died within a day after exposure (Nicholson and Cooper 1977). Neurological effects have also been reported in preclipped rabbits and rats after repeated application of endosulfan to the skin (Dikshith et al. 1988 Gupta and Chandra 1975). Dikshith et al. (1988) reported levels of a-, [3-, and total endosulfan in liver, kidney, brain, testes, fatty tissue, and blood 30 days after dermal application of endosulfan. 

Three animal studies were located regarding distribution of endosulfan in animals following dermal exposure (Dikshith et al. 1988 Hoechst 1986 Nicholson and Cooper 1977). Endosulfan was detected in the brain (0.73 ppm), liver (3.78 ppm), and rumen contents (0.10 ppm) of calves that died after dermal exposure to a dust formulation of endosulfan (Nicholson and Cooper 1977). Following a single dermal application of aqueous suspensions of 0.1, 0.83, and 10.13 mg/kg C-endosulfan to male Sprague-Dawley rats, low concentrations of endosulfan (ng/g levels) appeared in the blood and tissues (other than skin at and around the application site) after 1 hour (Hoechst 1986). The concentrations of endosulfan in the blood and tissues increased with the time of exposure and were proportional to the dose applied. The liver and kidney appeared to sequester radiolabel relative to the concentrations of radiolabel in the blood or fat. Endosulfan levels were approximately 10 times higher in the liver and kidney than in the fat, blood, and brain throughout the study (Hoechst 1986). 

Formulations of tetraethyl pyrophosphate as an emulsive concentrate proved to be relatively complex, considering the apparent ease of formulation. Because of the unstable nature of the chemical, dust formulations were considered impossible. It was found after extensive research work that a dust which would be stable for 10 days to 2 weeks could be made with a specially selected and processed filler. 

Technical parathion samples were analyzed in the same manner as the standard samples (Table I). For dust formulations at least 1 gram was taken for a sample and... 

Dust formulations of 0.48 and 1.97 kg/ha, to control wildlife flea populations 0.56 and 1.0 kg/ha, to control pale western cutworm (Agrotis orthogonia)... 

Pinocytosis. This process by which particles are absorbed can be an important factor in the ingestion of particulate formulations of chemicals (e.g., dust formulations, suspensions of wettable powders, etc.) however, it must not be confused with absorption by one of the above processes, where the agent has been released from particles. 

Tetraethylpyrophosphate (TEPP) was the first organophosphate compound to be used as an insecticide. This compound was developed in Germany during World War II and was substituted for nicotine as an insecticide. It is a white to amber hygroscopic liquid (bp, 155°C) that readily hydrolyzes in contact with water. Because of its tendency to hydrolyze and its extremely high toxicity to mammals, TEPP was used for only a very short time as an insecticide, although it is a very effective one. It was typically applied as an insecticidal dust formulation containing 1% TEPP. 

Uses Zineb is a light-colored powder or crystal. It is a polymer of ethylene (bis) thiocarbamate units linked with zinc. Zineb is used to prevent crop damage in the field and to protect harvested crops from deterioration during storage or transport. It was used to protect fruit and vegetable crops from a wide range of foliar and other diseases. It was available in the United States as wettable powder and dust formulations. Zineb can be formed by combining nabam and zinc sulfate in a spray tank.7121319... 

In this test series technical hydroprene and methoprene were compared with a residual dust formulation (RF 10%) on a latex paint substrate. 

Discussion. The increase in activity for the RF formulations of methoprene and the retention of activity for hydroprene was a surprise since formulations with a long residual generally tend to decrease acute activity. However, the increased stability, the decrease in volatility and the intense contact with a dust formulation by grooming cockroaches may have contributed to this result. It also appeared that methoprene (RF 10%) at 100 ug/cin was an effective control dose. 

A granular formulation is basically the same as a dust formulation. It contains toxicant (1%—10%) and an inert diluent. The major difference is in the particle size, granules ranging from 20 to 100 mesh, whereas dusts pass through 300 mesh screens. 

Emulsifiable concentrates leave little visible residue on plants. However, some plants are sensitive to the solvents and additives and damage (sometimes termed phytotoxicity) may occur. For this reason, an emulsifiable concentrate formulation may not be registered for a particular plant, even though wettable powder and dust formulations of the same active ingredient can be used. 

Despite their ease in handling, formulation, and application, dnsts are the least effective and, ultimately, the least economical of the pesticide formnla-tions. The reason is that dusts have a very poor rate of deposit on foliage, nnless it is wet from dew or rain. In agricultnre, for instance, an aerial application of a standard dust formulation of pesticide will result in 10 percent to 40 percent of the material reaching the crop. The remainder drifts npward and downwind. 

Commercial products include Satsan (dust formulation) and Prodan (bait formulation)... 

L-ephedrine - nearly 400 tonnes are being produced annually using the process know-how developed by CDRI, and bioinsecticide, a dust formulation substance based on Bacillus culture expressing killer larvicide for mosquitoes produced on a 15001 scale. The formulation has undergone extensive field evaluations and is claimed to be effective on both Anopheles and Culex species. Further scale-up operations have been tried in collaboration with Hindustan Antibiotics Limited (HAL),Pimpri in 17-kl batches [Behari, personal communication]. 

The dust formulation was applied similarly on com and beans as shown in the Table. There is not a clear reason wl corn should receive a lower amount unless it is found only in the high variability of the application. In this case the range of application on beans was 23 to 680 g, a 30-fold range On com it was better but still very large at 41 to 320 g. This clearly shows how variable an ordinary gardener s estimate is of how much pesticide is needed to do the Job. Some people just dust a tiny amount on the leaves while others produce totally white leaves. 

Table X. Amount of Carbaryl Active Ingredient Adhering to Individual Pads or Hands as a Function of Body Location and of Plant Height. Dust Formulation (12 Replications)...

Pigs may be treated with products that contain fenvalerate, permethrin, and pyrethrins. Fenvalerate is marketed as spray and pour-on formulations and can be applied to control the target parasites lice (pour-on), mites, and flies, and permethrin is marketed in spray, paint, dip, and dust formulations, and the target parasites are Uce, mites, ticks, and hom flies. 

Ready-to-use means the applicator need do nothing more than spread the product where it is required. As a consequence there are only two necessary ingredients in a dust formulation - active ingredient and carrier or solid diluent. 

Although used less in recent years, dust formulations still are employed in significant amounts. Solids can be ground into fine particles, mixed with inerts, such as talc and clay, and sometimes with adjuvants, and dusted on the plant surface or the soil. 

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