Farm family exposure to 2,4-D

DuPont, DowU Minn Public HealthAmerican Chemistry

Published in Environmental Health Perspectives

2,4-D characteristics

• Moderate acute oral LD50 (~ 350 mg/kg)• Not considered to cause mutagens, not

likely to be a carcinogen, no likely effect on reproductive system or development at human exposure rates

• Dermal penetration about 7% of skin dose

Study Purpose

• Identify real-world pesticide exposure and factors before, during, and after application

• 2, 4-D widely used in ag and non-ag applications

• Ranked 5th in ag uses – 2001• #1 in home, garden uses

Participants

• Certified pesticide applicators – South Carolina & Minnesota

• Farmer, spouse, 1+ child 4 to 17 years old• Live on farm• Farm at least 10 acres within 1 mi of home• Both amine and ester forms used

• Answer questions and allow observation• Collect all urine for 5 consecutive days –

day before, application day, 3 consecutive days after

• Allow field observer to document weather, application practices, family activities

Participants

Characteristics

• 34 families – 17 MN 17 SC• Average age - farmer 43.6y, spouse 40.2y• 53 children – 10.2y (4-17)• Applications during spring and early

summer

Practices – survey responses

• None had applied 2,4-D within 7 days before study• No spouses had mixed pesticides within

1 week of study• 2,4-D detectable in 70% of applicators,

62% of children, and 41% of spouses in pre-application urine samples

Practices

• 44% used enclosed cab tractors• 26% < 25 ac; 30% - 25 to 74 ac;

44% > 75 ac• 26% - 1 to 2 loads; 41% - 3 to 5 loads;

33% - 6 or more loads

Spray day observations

• 71% wore rubber gloves – during mixing /loading/ application• 47% had some contact w/ 2,4-D• 24% spouses & 38% (20) children present during

some of mix/load/ spray• 1 spouse & 8 children had chance for direct pesticide

contact

Spray day observations

• 11% ate during application• 32% used tobacco during application• 35% had spills during mixing and /or loading• 62% repaired equipment during the application• 65% spouses washed spray clothing

Results – Applicator

2,4-D in urine (ugm/L)

Peak urine concentration 1 day after applicationBiological half-life 17 hrs

2,4-D in urine (ugm/L)

Yes NoWore rubber gloves 43.8 236.2Closed cab 61.4 81.5Spill or accident 115.4 55.6Observed skin contact 188.8 30.5Equipment repair 184.1 40.2Used tobacco 106.7 59.6Ate while spraying 140.1 65.8

2,4-D in urine (ugm/L)

Acres <25 25-50 50-75 >75treated 57.0 12.9 100.9 99.7

No. of loads 1-2 3-5 >5 53.0 50.5 144.8

Factors associated with INCREASE in urinary 2,4-D concentrations

• Did not wear gloves• Treated more acres • Repaired equipment

2,4-D doses (mg/kg body wt)

Group Average dose

Maximum dose

Applicators 2.46 58.5Spouses 0.08 1.14

Children 4 – 11 0.22 7.2

Children > 11 0.32 31.1Spouses and children present at some time during mixing / loading/ spraying received greater doses than those not present

Limits of study

• Only one application evaluated per family• All were tractor boom sprayer

applications• Participation in study may have

affected behavior of applicators

Some lessons

• Application of 2,4-D resulted in exposure of applicator and family members \

• Amount of exposure was determined by potential for direct contact with the pesticide

• Use of rubber gloves when mixing, loading, and applying 2,4-D and repairing equipment was associated with greatly reduced urinary concentrations of 2,4-D

• Reduce children’s potential for contact

Reminders

• 2,4-D metabolism in the body is very different than that for other pesticides

• Actions that reduce exposure result in lower absorption of 2,4-D