Gregory Hall

Worker reentry into captan-treated grape fields in California

Loader/mixers/applicators and workers engaged in thinning and harvesting grapes in the central valley of California, were monitored for exposure to captan. Urinalyses for the captan metabolite, tetrahydrophthalimide (THPI), was intended to be the biological, index for exposure to captan. Dislodgeable residues of captan and THPI on foliage and grapes were measured as well as levels found in high volume air samplers placed in the field at the time of foliage sampling. Loader/mixer/ applicators were monitored following an application of a 10% dust and a wettable powder (W.P.) formulation just prior to thinning operations, and again at harvest with a W.P. formulation. Loader/ mixer/applicators were also monitored with and without respiratory protection with each treatment. The half-life of captan for the dust application was 12.8 days, and 19.6 days for W.P. Tetrahydrophthalimide levels were very low in all the field and clothing samples and were not a significant factor in worker exposure. Levels of captan in the air during the loading/mixing operation were higher. Although there were exceptions, gloves contained the highest levels of residues in the loader/mixer/applicators and the field workers. The relative levels found on the patches were reflective of the work habits of the workers. The applicators of the 10% dust had the highest captan levels in the personnel air samplers and on their mask or respirator pads. The results from the urine analysis, although THPI was found, showed no significant differences in trends between the pre- and post-exposure samples except possibly the individual who wore the respirator during the dusting operation. Pre- and post-exposure urine samples of field workers engaged in the thinning and harvesting operation showed no significant differences except workers engaged in the dusted plot. Dislodgeable foliage levels and glove residues from workers are used to measure potential dermal exposure, and since these two parameters were lowest in the dusted plots coupled with the same or slightly higher levels found in the high volume air samples in the dusted plot, they support the importance of investigating inhalation as a primary source of exposure to captan. Estimated dermal exposure in mg/person in relation to each pound of captan applied by loader/mixer/applicators was highest with those engaged in the dusting operation; the applicators during the harvest operation had much lower levels compared to the loader/ mixer/applicators during the thinning operation.

Furazolidone residues in chicken and swine tissues after feeding trials

Broiler chickens and swine fed furazolidone in their diet were sacrificed, and samples of liver, kidney, skin/fat and muscle were harvested and analyzed for furazolidone residue. Chickens fed 200 g of furazolidone/ton of feed were withdrawn from treatment 21, 14, 7, 5, 3, or 0 days before slaughter. Birds withdrawn from medication more than 5 days prior to slaughter had no residues in any of the tissues sampled. One of the 12 birds in each of the 5 day and 3 day withdrawal groups had detectable residues in the skin/fat. Seven of the 12 birds in the 0 day withdrawal group had residues of less than 2 ppb in skin/fat samples. Chickens fed 400 g furazolidone/ton of feed were withdrawn from treatment 0 days before slaughter. Residues of 0.7 to 3.5 ppb were found in the skin of these birds; residues were not found in other tissues. Swine were fed 300 g furazolidone/ton of feed for 2 weeks or 150 g/ton for 5 weeks. They were withdrawn from treatment 10, 7, 5, 3, or 0 days before slaughter. Tissue samples taken from these swine did not contain detectable furazolidone residues.

Chromatographic determination of dicofol and metabolites in egg yolks

Egg yolk was spiked withp,p′-dicofol (p,p′-DCF) (0.1–2.0 μg/gm),p,p′-dichlorobenzophenone (p,p′-DCBP) (0.1–2.0 (μg/gm), and 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p′- DDE) (0.05–1.0 μg/gm). The fortified egg yolk (2–5 g) was mixed with acetonitrile to extract non-fat organic materials. After removal of acetonitrile, the spiked chemicals were separated with a column chromatograph packed with acid alumina. Recovery efficiencies forp,p′-DCBP andp,p′-DDE were determined by gas chromatography, and forp,p′-dicofol by high performance liquid chromatography. The recovery efficiencies forp,p′-dicofol,p,p′-DCBP andp,p′-DDE were 77.2–93.8%, 84.1–101.1%, and 88.5–96.0%, respectively.

Dissipation of parathion and paraoxon on citrus foliage dust and dry soil surfaces in a treated orchard

Pesticides applied to an orchard may be transported via dust from the orchard floor to the foliage. The dust containing the pesticide facilitates oxygen analog formation. This study involves the evaluation of existing methods and new procedures for measuring pesticide fate (parathion and paraoxon) on soil surfaces in a field environment; the results were correlated with dislodgeable foliar residues. Residues in soil dust removed from the ground floor via vacuum varied considerably and did not correlate with dislodgeable foliar residues. Although residues found on masonite plates coated with a thin layer of soil were different from dislodgeable foliar residues, the ratios of paraoxon to parathion was very similar for the first 14 to 21 days. The thin-layer soil on the plates had serious deficiencies including difficulty of preparation in the field, handling of the coated plates, and physical movement of the soil from the plate due to environmental forces including rain. Soil tags prepared from fine mesh window screen saturated with soil resulted in approximately the same residue as the soil plates and at the same time avoided most of the deficiencies experienced with the plates. They were very resistant to physical forces, easy to prepare in the field, and not affected by environmental forces except appreciable quantities of rain. The results should encourage the use of soil screen tags, not in lieu of but along with other methods when conducting field studies with pesticides involving worker safety.