Hands, exposure

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. 

Occasionally, hand exposure must be tested while wearing protective gloves. This may be easily accomplished by wearing the protective gloves over the top of the cotton gloves. 

Currently, hand exposure is predominately measured using the hand wash technique. Numerous solvents have been suggested for use in this procedure however, rubbing alcohol or a mild detergent in water has been the most commonly used. 

Head, neck, and hand exposures were measured using methods outlined in the literature.4 Head patches were used to estimate dermal exposure to the neck and face of the worker. Handwashes were conducted using a 0.008% DSS solution and collected in 2-L Pyrex bowls. The handwash was repeated with distilled water, and the two handwash solutions were combined. The pooled handwash was then partitioned with ethyl acetate to remove the chlorpyrifos from the aqueous phase. An aliquot of the ethyl acetate was shipped to the analytical laboratory for analysis of chlorpyrifos. 

Doses of chlorpyrifos in human volunteers were also estimated using physical measurements. Air sampling was conducted in order to estimate the inhalation dose to each volunteer. Dislodgeable residues were also measured throughout the study to estimate the dermal contribution to total dose. Finally, hand rinses were conducted on each volunteer immediately following the 4-hr activity period to assess the potential contribution to total dose from hand exposure and to estimate an oral dose to a crawling child. 

At the termination of the activity period, each participant s hands were held over a bowl and doused with 250 mL of a dilute dioctyl sodium sulfosucci-nate (anionic surfactant) mixture. This soap wash was followed by a 250-mL rinse with deionized water. The soap and water fractions were stored together in the same container. Fifteen grams of sodium chloride were added to the container to facilitate phase separation. The chlorpyrifos was partitioned with 200 mL of ethyl acetate, which was also used to rinse the bowl. The ethyl acetate extract was later analyzed for chlorpyrifos content. The amount of test substance removed was used to assess adult hand exposures and dose and also to assess the theoretical amount of test substance removed when children put their hands in their mouths. 

Table 4 summarizes the results of using physical techniques to estimate total chlorpyrifos doses of adults following activity on treated grass. Total doses ranged from 3.03 pg/kg to 5.04 pg/kg (mean, 3.88 pg/kg). Approximately 85% of the chlorpyrifos dose came from the whole body dermal route. About 15% came from the inhalation route. Hand exposure was insignificant. 

For applicators, hand exposure was approximately 15% of the total potential dermal exposure. 

No significant relationship between the IPP excreted and hand exposure was observed for the applicators wearing normal work clothing or for protective clothing (p = 0.09 and p = 0.73, respectively). Skin moisture variables did not contribute significantly to the explained variation. 

Fenske, R.A., Bimbaum, S.G., Methner, M.M., and Soto, R. (1989) Methods for assessing fieldworker hand exposure to pesticides during peach harvesting, Bull. Environ. Contam. Toxicol, 43 805-815. 

Neanthes arenaceodentata is the most sensitive marine organism yet tested. In worms exposed to sublethal concentrations of CC6, feeding was disrupted after 14 days at 79 pg/L (USEPA 1980), reproduction ceased after 440 days (three generations) at 100 pg/L (Oshida et al. 1981), brood size was reduced after 309 to 440 days at 12.5 to 16.0 pg/L (Oshida et al. 1981 Oshida and Word 1982), and abnormalities in larval development increased after 5 months at 25 pg/L (Reish 1977). On the other hand, exposure for 293 days (two generations) in 50,400 pg Cr+3/L caused no adverse effects on survival, maturation time required for spawning, or brood size (Oshida et al. 1981). The poly-chaete Capitella capitata was more resistant than Neanthes, a decrease in brood size was noted only after exposure for 5 months to 50 and 100 pg Cr+6/L (USEPA 1980). 

A number of effects have been associated with chronic exposure to jet fuel in factory workers (Knave et al. 1978). These effects included increases in the occurrence of neurasthenia (anxiety and/or mental depression, fatigue, depressed mood, lack of initiative, dizziness, palpitations, thoracic oppression, sleep disturbances) and eye irritation. Psychological tests found that attention and sensorimotor speed were impaired in exposed workers, but there were no effects on memory functions or manual dexterity. EEG tests suggested that there may have been instability in the thalamocortical system in the exposed group. However, the type of jet fuels were not noted nor was there a control for exposure to other compounds. Inhalation exposure is likely since jet fuel vapor was detected by the study authors however, dermal and oral (i.e., eating with contaminated hands) exposures may also be possible. 

Exposure of the silver chloride or bromide to light results in an increase in the nitrogen yield. This is to be expected, because the action of the light supplies nuclei for the catalyzed reaction. On the other hand, exposure of silver thiocyanate, which is relatively insensitive to the action of light, has little or no effect on the amount of nitrogen obtained on subsequent reduction with hydroxylamine. 

Process Operations. The operation of a modem chemical plant is typically computer controlled and does not involve any routine operator contact with the feedstock, intermediates, or product (see Process control). There are, however, a few actions the operators may need to take which can involve contact with process materials. Sampling of process streams is one such task. Whereas use of on-line analyzers has substantially reduced the need for operator-collected samples, the latter are necessary to check the on-line analyzer or wherever on-line analyzers are not used. Exposure during sampling can be very high if the sampling line is flushed by running a quantity of a volatile liquid out on the pad. On the other hand, exposure can be very low where the sample is collected in a bomb from a closed loop. Worker care in following prescribed practices is important. 

D removal from hydrogenated films was also studied under exposure to other atmospheric gases. Nitrogen exposure and heating in vacuum at or below 570 K was found to have no effect on the release of deuterium from D-implanted layers [63]. On the other hand, exposure of D-implanted layers [63], as well as TFTR co-deposits [61], to water vapor did result in D removal, but with no evidence of C erosion. It is suggested that D is removed via isotope... 

Washing or wiping the skin can remove chemical deposits, and chemical concentrations can be measured (Durham and Wolfe, 1962 Davis, 1980). Wash techniques are generally used only to assess hand exposure, while wiping techniques can, in theory, be applied to other skin surfaces. 

Davis, J.E., E.R. Stevens and D.C. Staff (1983). Potential Exposure of Apple Thinners to Azinphosmethyl and Comparison of Two Methods for Assessment of Hand Exposure, Bull. Environ. Contam. Toxicol., 31, 631-638. 

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