J. H. Stamper

Dicofol exposure to Florida citrus applicators: Effects of protective clothing

Mixer-loaders and applicators of the pesticide dicofol in Florida citrus groves were monitored for exposure. Alpha-cellulose pads were placed inside and outside regular work clothing. When protective suits were in use, pads were also placed outside the suit. Dicofol accumulation rates were measured when gloves and/or facemasks were worn. Hand rinses were collected. Results showed that an ungloved, normally attired applicator reduced his total dermal exposure 38% by wearing a disposable Tyvek® protective suit, 27% by wearing gloves, and 65% by wearing both. Suits reduced total dermal exposure by 40% for mixer-loaders, but the use of gloves led to an exposure increase, probably because the inside of the gloves became contaminated.

The Development and Use of a Universal Model to Predict Tree Crop Harvester Pesticide Exposure

A simple regression model is presented for predicting the transfer of residual foliar applied pesticide to the body of a Florida citrus harvester. This model is dependent on work rate and residue concentration and agrees with an earlier model derived from similar data taken from a California study. This suggests that observed regional differences in the morbidity of harvesters in treated fields may be due to regional differences in foliar pesticide residue levels rather than regional differences in transport mechanisms of pesticide from foliage to worker. Eventual metabolite output in worker urine is also predicted.

Worker exposure to ethion in florida citrus

Dermal and respiratory exposure to ethion was determined for 17 men in eight spray crews in Florida citrus spray operations. Respiratory exposure was less than 1% of the total exposure. Hands represented 42% of the total body exposure for applicators and 76% for suppliers. At one location, suppliers exhibited a larger decrease in ChE activity than applicators. This difference appeared related to the higher mean dermal ethion exposure to suppliers. Acute symptoms of organophosphorous poisoning were not observed. The total percent/hr of the probable human dermal LD50 was very low in all cases. These data indicate a relatively low potential acute hazard to workers applying ethion with air blast equipment under the conditions of this study.

Pesticide exposure to greenhouse handgunners

The exposure of pesticide applicators in a commercial greenhouse facility was assessed. Data were collected from four handgunners who applied fluvalinate (insecticide), chlorpyrifos (insecticide), ethazol (fungicide), and dicofol (miticide). Potential exposure was measured with exposure pads placed outside all clothing of the applicator. Handwashes and air samples were also collected, as were pre- and post-exposure tank mixture samples. Pesticide penetration was measured with exposure pads placed inside protective clothing.When all exposure assessments were normalized for spray rate, it was determined that applicators were at significantly greater potential dermal risk (excluding hands) from fluvalinate. The normalized air samples showed significantly more exposure to the applicator from ethazol. Exposure to outside pads was primarily (84%) to the legs of the applicators. Ethazol penetrated Tyvek® coveralls more readily than the other compounds. Tank mixture analyses suggested that the wettable powder formulations were not well-mixed.

Worker exposure to arsenic in Florida grapefruit spray operations

Dermal and respiratory exposures of workers to arsenic when mixing, loading, and applying lead arsenate as a maturity spray to Florida grapefruit were determined. Respiratory exposure contributed <0.01% of total body exposure. The average level of dermal arsenic exposure was higher for suppliers than for applicators. Exposure was significantly higher for the hands and legs than other areas of the body. Accumulated total body exposure to arsenic was correlated with the urinary arsenic concentration. The mean dermal exposure of workers using a spray mixture of 0.1% lead arsenate was significantly lower than the average dermal exposure of workers applying arsenic with a 0.3% spray mixture. Although suppliers excreted an average daily total arsenic concentration of 228 ppb, slightly greater than the 200 ppb threshold value suggestive of arsenic poisoning, the average daily excretion of total arsenic by the applicators was 83 ppb, less than the threshold value. Exposure to arsenic of all workers was lower than the shortterm no-effect level set by the U.S. Environmental Protection Agency.

A model of the daily photosynthetic rate in a tree

Abstract A theoretical model of the daily net photosynthetic rate (kg glucose/day) of a tree is formulated as an analytical function of certain agricultural and meteorological variables. The experimental, single-leaf rate (kg glucose/m 2 leaf area - day) is integrated over both the tree canopy and the photoperiod for spherically and cubically shaped canopies. Consideration is given to cloud cover and mutual shading, one tree by another. Results are analyzed with respect to the efficiency of light energy conversion by a tree and variations in tree canopy height and shape. Quantitative comparisons with experimental data are made, primarily for the case of orange trees. Proportions of leaf photosynthate allocated to various tree parts are generated.

Quantification of human exposure to ethion using saliva

Abstract Ethion and ethion metabolites in saliva and ethion metabolites in urine were monitored in pesticide workers and control subjects. Pesticide worker saliva averaged from 86–4130 ppb ethion and 0.30−7.00 ppm urinary ethion metabolites. Low and inconsistent ethion metabolites were found in pesticide worker saliva, none in control subject saliva, and 1.0 ppb in control subject urine. Pesticide worker urinary ethion metabolites and salivary ethion had an overall correlation of 0.55 at the 0.0001 level. Saliva may be an appropriate substrate to confirm pesticide exposure and to estimate internal pesticide dose in humans.

Pesticide exposure to greenhouse foggers

Abstract The exposure of pesticide applicators in a commercial greenhouse facility was assessed. Data were collected from three subjects who applied fluvalinate, chlorpyrifos, and ethazol with a fogging device. Potential exposure was measured with exposure pads placed outside all clothing of the applicator. Handwashes and air samples were also collected, as were pre- and post-exposure tank mixture samples. Pesticide penetration was measured with exposure pads placed inside protective clothing. When all exposure assessments were normalized for spray rate, it was determined that applicators were at significantly greater potential dermal risk (excluding hands) from fluvalinate. Exposure to outside pads was primarily (75%) on the extremities of the applicators. Ethazol penetrated Tyvek® coveralls the most. Tank mixture analyses suggested that the wettable powder formulations were not well-mixed.

Exposure of Florida airboat aquatic weed applicators to 2,4-Dichlorophenoxyacetic acid (2,4-D)

Abstract Florida airboat handgun applicators were monitored for exposure to 2,4-Dichlorophenoxyacetic acid (2,4-D). Four applicators were monitored with air samplers, α -cellulose patches, and 24 hr urine samples on 10 separate days. Estimated total body exposure averaged 15 ± 2 mg/hr, of which 74% was to the legs and feet with an additional 18% to the hands and arms. Estimated respiratory exposure was about 0.03% of the total body exposure. Twenty-four hr urinary 2,4-D ranged from 0.190–0.645 mg. The use of disposable coveralls and effective hand protection would markedly reduce this exposure.

Protection afforded greenhouse pesticide applicators by coveralls: A field test

Applicators of chlorpyrifos, fluvalinate, and ethazol to ornamentals in a Florida greenhouse were monitored for exposure in a replicated experiment. Pesticide exposure was assessed, using pads placed inside and outside three types of protective coveralls. Potential total body accumulation rates, excluding hands, as calculated from outside pads, depended strongly upon the rate at which pesticide left the spray nozzles. When these total body rates were normalized for spray rate, the mean results, in mg-deposited/kg-sprayed, ranged from 166 to 1126, depending upon the compound applied and the application device. Overall penetration of pesticide through a disposable synthetic coverall was 3±1% for chlorpyrifos and fluvalinate, and 35±9% for ethazol. Penetration through a reusable treated twill coverall was 19±6% for chlorpyrifos, 22±13% for fluvalinate, and 38±5% for ethazol.