Post-application

The times of sample collection for a single paddy survey are set with respect to the application time, such as just before an application, immediately after, and 1, 3, and 7 days post-application, and at longer intervals as appropriate. For an area survey of water and waterway sediments, samples are usually collected periodically over a cultivation season focusing on the application time. 

Localized, or field-scale, studies generally assess pesticides drifting off-target during application or from post-application volatilization over short sampling intervals. The... 

Location Species N Days 0-12 post-application Diazinon n concentration ... 

Post-treatment soil and earthworm samples were collected from all sites on Day 0 (application day), 1,2,3,4,6,8,12,16 and 24 on treated sites. Samples on Day 0 were collected within 3h of chemical application. Soil from control sites was sampled on Day 7 post-application only. One in-furrow soil sample from each control station was collected and the six samples were pooled. Within a given field, earthworms from each of the six stations were composited for analysis by combining all in-furrow samples into one composite and all between-furrow samples into another. Earthworms from control sites were sampled in-furrow on Day 8 and 16 post-planting only. 

Spatially heterogenous distributions of crop protection products, within and among test sites, will result from well controlled applications. The soil CEF concentrations ranged from a high of 2.3 qgg at one station on site 1 Day 0 to none detected in 10 samples from various stations several days post-application. The measured mean soil CEF concentrations were between 0.2 and 1.0qgg on Day 0. The theoretical CEF concentration immediately after application was calculated to be... 

Distributions of pesticide concentrations in potential food items for avian species are required to estimate the contribution of food to exposure of birds in different regions where the test chemical may be used. On treated fields, detectable CEF residues were found in 102 of 207 earthworm samples. No earthworm samples collected from control fields (N = 28) contained detectable CEF. Average CEF concentrations in earthworms reached maxima 1-4 days post-application (Table 3). Mean CEF residues in earthworms fell below 0.1 qg g after 8 days post-application. This... 

Of those matrices measured, worms collected from treated fields present the most significant potential route of exposure for those species of wildlife which rely on them as a major food source. Worms were the matrix, aside from soil, with the highest frequency of detection (49% of samples collected on treated sites post-application) and the highest mean concentrations (0.025-0.15 qg g on treated sites). 

Properly designed o/w creams are elegant drug-de-livery systems, pleasing in both appearance and feel post application. They are nongreasy and are easily rinsed off of the skin. They are good for most topical purposes and are considered particularly suited for application to oozing wounds. 

Type of post-application activity (work task) ... 

Gwynn RL, Chappie AC, Smits PH. Post application persistence of entomopathogenic nematodes. In Gwynn RL, Smits PH, Griffin C, Ehlers RU, Boemare N, Masson JP, editors. Cost 819 entomopathogenic nematodes. Application and persistence of entomopathogenic nematodes. Luxembourg European Communities 1999. pp. 89-94. 

Urinary excretion of C1 was observed in rats that had been administered Alcide, an antimicrobial compound consisting of sodium chlorite and lactic acid that form chlorine dioxide when mixed (Scatina et al. 1984). The rats had received 10 daily dermal applications, followed by an application of radiolabeled Alcide. Urinary excretion was greatest in the first 24 hours post application the half-time of urinary elimination was 64 hours. The excreted radioactivity consisted of approximately equal portions of chloride ion and chlorite. No radioactivity was detected in feces or expired air. 

Figure 30.5 Concentrations in selected midwestem streams during post-application runoff in 1989, 1990, 1994, 1995, and 1999 for (A) atrazine and cyanazine, (B) propazine and simazine, and (C) cyanazine amide, deethylatrazine, and deisopropyl atrazine.

Upon release the formulated control agent is partitioned between the air, the forest vegetation and the forest floor. It is the post application loss of insecticides from conifers which is the subject of the following discussion. Volatilization has become increasingly recognized as a significant factor which limits the efficiency of pesticides and provides a major pathway to general environmental contamination. 

In the absence of direct field measurements of pesticide fluxes eminating from a sprayed forest a series of suppositions may be drawn from similar observations of losses from treated agricultural crops. The volatilization of dieldrin and heptachlor from a grass pasture was characterized by rather marked diurnal variations in vertical flux intensities of both insecticides during the initial days post application (12). The authors concluded that the volatilization ceased or was greatly reduced with decreased solar radiance. Estimated relative vapour concentrations of dieldrin rapidly declined from saturation 2 hours post application to 10% by evening. This parameter reached a maximum of 30 - 40% on day 2 and 20 - 25% on day 3. Although the saturated vapour concentration of heptachlor is approximately fifty... 

Table III shows the levels of aminocarb present in mayfly nymphs sampled from Portage Brook following the 1st application. Aminocarb concentrations found in insects were not high and no breakdown products of the insecticides were found. The peak concentration detected is only 20 ppb (1 h post-application) exposed to a maximum of 2.26 ppb aminocarb in water, representing a concentration factor of oa 9. Residues declined to below detection limits ( < 20 ppb) rapidly afterwards coinciding with the disappearance of residues in stream water indicating that the uptake and bioconcentration potential by the insects for aminocarb were not high. Further work is necessary to confirm this observation since Penny (16) reported that the other insecticide, fenitrothion, is readily bioaccumulated by aquatic insects yielding a concentration factor of about 60.

Lack of ensuring that there is no post-application exposure. Excretion curves for several workers in our studies indicate that occasionally some avenue of re-exposure occurs after the actual spray day. 

Corbet et al. (1983) reported that a rooted plant species (Potemagetonpectimatus) and a surface-dwelling duckweed (Lemna sp.) accumulated concentrations of 1,3,6,8-TCDD of 280 and 105 ng/g (dry weight), respectively, following exposure to water containing 1,000 ng/L (ppt). The maximum concentrations were observed 8 days post-application and represented 6% of the total TCDD applied. These results are similar to those reported by Tsushimoto et al. (1982) in an outdoor pond study, in which a maximum bioaccumulation of 2,3,7,8-TCDD in the pond weeds Elodea nuttali and Ceratophyllon demersum equivalent to a BCF of 130 occurred after 5 days of exposure. In both studies, the tissue concentrations reached equilibrium in approximately 20 days and remained constant until the end of the experiment (approximately 58 and 170 days, respectively). These experimental data indicate that CDDs can accumulation in aquatic plant species through waterborne exposure. 

Taylor, A.W. Post-application volatilization of pesticides under field conditions. J. Air Pollut. Contr. Assoc., 1978, 28, 922. 

---