Loaders application

Both inner and outer whole-body dosimeters are common tools to measure successfully dermal exposure to pesticide workers and are employed in a variety of ways in mixer-loader/applicator or re-entry studies. 

Hand exposures of mixer-loader/applicator and re-entry workers have been measured using a variety of techniques in the past. The most common methods are using gloves as dosimeters and washing the hands with various solvents post-exposure. 

Observations of the test subjects during the course of the field portion of the worker exposure or re-entry study are extremely important in order to interpret the data that are gathered at the field site and to interpret the final analytical data. There are two schools of thought when making observations of field workers during mixer-loader/applicator worker exposure or re-entry studies. 

D.R. Hackathorn and D.C. Eberhart, Database proposal for use in predicting mixer-loader/applicator exposure, in Dermal Exposure Related to Pesticide Use Discussion of Risk Assessment, ed. R.C. Honeycutt, G. Zweig, and N.N. Ragsdale, ACS Symposium Series 273, American Chemical Society, Washington, DC, pp. 341-355 (1985). 

Assume 100% respiratory absorption of chlorpyrifos except for mixer-loaders, applicators, and cleanup workers in California who wore respirators which blocked 100% of the respiratory exposure. 

Types of workers Mixer-loaders Applicators Cleanup workers Mixer-loaders Applicators Citrus pickers Citrus primers Scouts... 

Table 3 Chlorpyrifos Mixer-Loader, Applicator Exposure Study Parameters...

The third approach for estimating risk from field data is the use of Monte Carlo simulation. This has been done in this study for the greenhouse mixer/loader/applicators,5 where the model that describes the relationship between the input variables is expressed by the following equation ... 

For comparison purposes, the results of the various analyses and risk estimates for the mixers/loaders/applicators in greenhouses are summarized in Table 6. All of these analyses present the risk assessor with some information about the possible hazards to workers who are exposed to... 

Table 6 Comparison of Exposure and Risks for Greenhouse Mixers/ Loaders/ Applicators...

Chester, G., Loftus, N.J., Woollen, B.H., and Anema, B.P. (1990b) The effectiveness of protective clothing in reducing dermal exposure to, and absorption of, the herbicide fluazifop-P-butyl by mixer-loader-applicators using tractor sprayers, in Book of Abstracts, Seventh International Congress of Pesticide Chemistry, Vol. Ill, Freshe, H. and Kesseler-Smith, E., Eds., Conway, Hamburg. 

Generally speaking, the equipment that workers use and the type of agricultural work performed while handling pesticides or pesticide-treated commodities have a major impact on the level of exposure a worker receives. Neat work habits generally lead to lower exposure for agricultural workers who handle pesticides. The current Pesticide Handlers Exposure Database (PHED), which is used to predict exposure to mixers/loaders/applicators, is based on this concept. 

In one study (2), plasma and RBC ChE activities were followed from May to September in two mixer-loaders (ML) who used a Swampmate closed-transfer system (Cherlor Manufacturing Co., Salinas, California), and in three mixer-loader applicators (MLA) who used a Model SS 12-4 closed-transfer system (Soil Serv, Salinas, California). The results shown in Fig. 1 indicate that the activities of plasma and RBC ChE were depressed during the application season, but returned to normal by the middle of September. The MLA showed less plasma and RBC ChE depression. It is interesting to note that the plasma ChE showed the "rebound effect," recording levels way above baseline. 

Figure 1. Change in blood cholinesterase activities of two mixer-loaders (ML) and three mixer-loader applicators (MLA) from their April 4 baselines during the weeks between May 14 and September 13,1976 (2). Mixer-loaders used the Swampmate (Cherlor Mfg. Co., Inc., Salinas, CA) while mixer-loader applicators used a Model SS 12-4 Closed System (SoilServ, Salinas, CA).

Glass Impinger, flow rate = 0.014 m /min. tractor mounted near breathing zone of driver. Samples collected from work zones of 4 mixer-loader applicators (F, G, H, I). 

Table II. Mevinphos residues on cloth patches3 worn at various sites on the body of mixer-loader applicators...

Mixer-loader applicator CNot detected. Table from Knaak et al. (3). 

The program for the medical supervision of mixer-loaders, applicators, and flaggers exposed more than 30 hours in 30 days to Category I and II OP s and carbamates has been successful but the details of the plan are under review. 

Mixer, Loader, Applicator Exposure Studies. A major difficulty in making hazard assessments for mixers, loaders, and applicators is the lack of information on how much of the pesticide may be inhaled or may reach the skin under a typical use situation. 

Comer et al. (2) therefore evaluated the effect of exposure to carbaryl (1-naphthyl methylcarbamate) on formulating plant workers and on workers applying carbaryl to fruit orchards with a tractor-drawn air-blast sprayer. However, information was still needed on the persistence of carbaryl in apple orchards and on the resultant exposure of workers who re-enter treated orchards. Further, no studies had been done on other types of crops. The present study was undertaken to determine the exposure of agricultural workers to carbaryl as a function of type of formulation, application equipment, application method, and type of work performed (i.e., mixer-loader, applicator, flagman, bystander, and apple thinners). 

D. The participants included 26 ground applicators in North Dakota after a single exposure and 17 aerial applicators in Washington during intermittent exposure. The objective was to ascertain worker exposure base-levels of 2,4-D under normal use conditions. Mean daily urinary excretion of 2,4-D by workers involved in aerial applications was 0.006 mg/kg body weight for pilots and 0.02 mg/kg for mixer/loaders from intermittent exposure. Workers involved in ground applications had maximum mean one-day 2,4-D urinary excretion of 0.002, 0.003, and 0.004 mg/kg, respectively, for applicators, mixer/loaders, and mixer/loader/applicators from a one-time exposure. The Ej/2 (half-elimination time for total... 

Commercial aerial applicator Commercial aerial mixer/loader All commercial aerial Commercial ground applicator Commercial ground mixer/loader All commercial ground 7 Mixer/Loader applicator 7 Applicator Mixer/Loader... 

Mixer/loader/applicator using high-pressure hand wand (greenhouse ornamentals) Empire 20 formulation... 

Krieger, R.I., C. Blewett, S. Echniston, H.R. Fong, D.D. Meinders, L.P. O Connell, F. Schneider, J. Spencer, T. Thongsinthusak and J.H. Ross (1990). Gauging pesticide exposure of handlers (mixer/loader/applicators) and harvesters in California agriculture. 

Applicator Mixer/loader Commercial aerial Applicator Mixer/loader Commercial ground Mixer/loader + applicator Applicator Mixer/loader Growers... 

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