Dermal Exposure of Workers at Residues of Deltamethrin

Dermal Exposure of Workers at Residues of Deltamethrin in Treated Plants, in the Reentry Cotton Crop After Spraying Mauricio Rotundo 1, Geraldo Papa 1, Dhiego Duvaresch 1, Willian Takao 1, and Luiz Roberto Pimentel Trevizan 2. (1) Paulista State University - Unesp, Rua Farroupilha 162, Ilha Solteira-SP, 15385000, Brazil, (2) São Paulo University - Esalq/USP, Av. Padua Dias, 11, Piracicaba-SP, 13418 -900, Brazil

Introduction

Introduction • Exposure to rays ultra-violet • Excessive noise • Poisonous animals (snake, wasps. . . ) • Pesticides exposure

Primary sceneries of exposure Secundary sceneries Re-entry Sampling Weed control Harvest

Re-entry period A period of time that elapses before an individual re-enters a treated area, or the period of time that defines when individuals may re-enter a treated area

Researches of dermal exposure for pesticides in re-entry of cotton crop are very few in the specialized bibliography

Dislodgeable residues

The dislodgeable residues it is a portion of a residue of the pesticide in a vegetation treated that is removed quickly and it can be constituted in risk for farmworkers or scouts

Objective of this study

Objective Study the dermal exposure of scouts in the reentry of cotton crop after spraying with deltamethrin insecticide (Decis 25 EC), quantifying the transfer of residues in the plants for the clothes of the scout and to compare the results with the interval established by Brazilian legislation

Materials and Methods

Experimental Farm of Unesp University

Selvíria/MS/Brazil

• Assessment of dermal exposure • Whole Body Method (pants and shirt) • Absorbent gloves • Raw cotton

105 days after seeding (1. 6 m/height/5. 2 feet)

* Application * Volume 250 L/ha * Nozzles TXVK-8 (conic) * Decis 25 EC • 400 ml c. p/ha or 0. 032 gal c. p/ac

30 minutes 7 days 3 days 1 day 5 h 1 h 3 min

Front Back 1. Chest; 2. Back; 3. Thighs front/back; 4. Legs front/back; 5. Gloves (hands); 6. Forearms front/back; 7. Arms front/back

Estimates of Safety

Estimate of Working Condition Safe 1 mg/kg/day MOS = NOEL X 70 AEQ X 100 NOEL is the “No Observable Effect Level” The AEQ is the absorbed exposure quantity (dermal penetration or inhalation) in (mg day-1). The dermal penetration was considered as 10% (Protocol of WHO) The number 100 multiplying AEQ is a factor of safety used to compensate the extrapolation of the toxicological data obtained in laboratory animals The used criterion, if MOS ≥ 1, the condition is classified as safe If MOS < 1, the condition is classified as unsafe

Estimate the Safe Work Duration (SWD) SWD = MOS x TSW Where: -TSW it is the time of exposure in hours (Work day: 8 h) - SWD is the time of safe work, expressed in hours of safe exposure (h)

Estimative of Dermal Dose Tolerable 1000 mg/kg/day Dtol = NOELD x 70 = mg/day 25 x AF 25 = factor of safety AF is the factor of absorption of the substance for the skin (10%)

Estimative of Poisonous Dose > 2000 mg/kg/day % DT = 1. 1 x DE x 100 LD 50 x 70 LD 50: is the amount of a pesticide, given all at once, which causes the death of 50% (one half) of a group of test animals. The LD 50 is one way to measure the short-term poisoning potential (acute toxicity) of a pesticide

Analytical Method Validation - GPL Stock Solution of deltamethrin Stantard solution / fortification / recovery Concentrations of 1. 6 and 16 µg/m 2 respectively with 5 and 4 repetitions Chromatography technique in gaseous phase Analytical method, adapted of Nilsson & Papantoni (1996)

Results

Percentage (%) of recovery of deltamethrin residues in samples of cotton (vegetable fiber) fortified Fortification levels (µg/m 2) a ± sd (%) Repetitions (%) 1 2 3 4 5 1. 6 102 109 93 115 106 105 ± 8 16 86 88 ± 6. 6 97 89 81 -- acceptance criterion 70 ≥ % REC ≤ 120 %

Residues of deltamethrin (µg/m 2) relative of dermal exposure in parts of dosimeters of raw cotton relative of different parts of human body (average of 4 repetitions) 0, 05 h 1 h 5 h 24 h 72 h 168 h 3 min 1 h 5 h 24 h 3 daa 7 daa 1. Chest 57. 78 52. 71 24. 84 6. 23 0. 77 0. 59 2. Back 48. 34 22. 15 6. 50 2. 27 0. 53 0. 36 3. Thighs 38. 87 43. 26 18. 20 2. 84 0. 62 0. 44 4. Legs 45. 02 18. 36 22. 29 1. 28 0. 71 0. 76 5. Hands 115. 98 72. 96 30. 49 10. 45 2. 92 1. 15 6. Forearms 117. 71 87. 39 34. 63 12. 20 2. 02 0. 84 7. Arms 81. 76 37. 58 21. 46 3. 37 1. 05 0. 59 Areas of the body

Decrease of dermal exposure Second re-entry First re-entry 3 minutes 60 minutes 34%

Decrease of dermal exposure Second re-entry Third re-entry 60 minutes 5 hours 53%

Decrease of dermal exposure First re-entry Third re-entry 3 minutes 5 hours 69%

Decrease of dermal exposure Fourth Re-entry 1 day 8%

Decrease of dermal exposure Fifth Re-entry 3 days 2%

Decrease of dermal exposure Sixth Re-entry 7 days 1%

Gunther (1969) Giles & Blewet (1991) Degradation phase Persistence phase

1. 8 R 2 = 0. 8716 1. 4 mg/day 1. 2 1 0. 8 0. 6 0. 4 0. 2 0 0 20 40 60 80 100 120 hours after spraying 140 160 180 Regression curve of dermal exposure (mg/day) of deltamethrin in the body of scout, relative the dermal exposure in each time of re-entry (in hours) in the cotton crop after application (extrapolation for workday of 8 hours)

Percentege of dermal exposure to deltamethrin residues in the cotton plants in the clothes of scouts, in agreement with parts of the human body, in each time of re-entry in the cotton crop after application (average of 4 repetitions)

Forearms/hands = 61. 27% 23. 4% of the area of the human body

Results of estimates

Margin of safety, Poisonous Dose (% PD/day), Dermal Dose Tolerable and Save Work Duration of scout in the cotton crop. Selvíria/MS/Brazil, 2007 deltamethrin EC (Decis 25 EC) 400 ml c. p/ha (0. 032 gal c. p/ac) Estimates of Safety 3 min 1 h 5 h 24 h 3 daa 7 daa MOS (Margin of safety) 3. 5 5. 3 10. 9 51. 5 240 377 Poisonous Dose (% PD/day) 0. 0013 0. 0009 0. 0004 Dermal Dose Tolerable (mg/day) in comparison with the dermal dose found (mg/day) 280 (1. 77) 280 (1. 19) 280 (0. 58) 280 (0. 12) 280 (0. 01) Save Work Duration (SWD) 28. 7 42. 4 87. 6 412 1920 3021 0. 00009 0. 00002 0. 00001

Conclusions

Conclusions The analytical method used for the analyses of deltamethrin residues in dosimeters made with vegetable fiber (raw cotton) is adapted and feasible

Conclusions The group for the forearms/hands concentrated 61. 27% of presents residues in the dosimeters Results of deltamethrin amounts trapped on cotton clothes showed that 24 h as a reentry for Decis 25 EC in cotton is overestimated by Brazilian legislation

Acknowledgements

Acknowledgements The authors wish to acknowledge the financial support of The State of São Paulo Research Foundation (FAPESP), project number 04/12505 -0 and the LARP/ESALQ/USP, Laboratory of Pesticides Residues of São Paulo University, for the analysis of the deltamethrin

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