Farm family exposure to glyphosate

MonsantoU Mn School of Public Health

Rollins School of Public Health Exponent Corp.

Published in Environmental Health Perspectives

Glyphosate characteristics

• Low acute oral LD50 (> 5,000 mg/kg)

• Not considered to cause mutagens, cancers, no effect on reproductive system or development

• Low vapor pressure – low inhalation potential• Dermal penetration < 2% of dose placed on skin

Overall low potential for harm to applicators

Study Purpose

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

• Glyphosate – 2nd in pounds applied in US agriculture – US EPA 2002

Participants

• Certified pesticide applicators – South Carolina & Minnesota

• Farmer, spouse, 1+ child 4 to 18 years old• Live on farm• Farm at least 10 acres within 1 mi of residence• Make at least 1 glyphosate application / yr

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

before, application day, 3 consecutive days after

• 48 families – 78 children• Field observer documented weather,

application practices, family activities

Participants

Characteristics

• 48 families – 25 MN 23 SC• Average age – farmer 45, spouse 42• Used pesticides for 23.9 years• 15% cigarette smokers• Few spouses personally mixed pesticides

Practices – survey responses

• 29% applied glyphosate within 7 days of study

• 22% never wore protective gloves• 27% changed gloves 1 to 4 times per

season• 96% of spouses had not mix pesticides

within 1 week of study

Practices

• 60% used enclosed cab tractors• 33% treated 10 to 44 ac; 33% - 45 to 145 ac;

33% - 125 to 439ac• 25% - 1 to 2 loads; 31% - 3 loads; 25% 4 to 6

loads; 19% 7 to 12 loads• Most applied Roundup Ultra

Spray day observations

• 71% wore rubber gloves - mixing /loading/ application

• 31% had skin contact w/ glyphosate• 15% spills during mixing and /or loading• 27% repaired their equipment at some

time during the application

Results – Applicator

Detectable glyphosate in urineLevel ranged from <1 ppb to 332 ppbSome sprayed > 100 acres – no detection in

urine60% of application day samples positive

27% positive 3 days after

• 96% used rubber gloves

1.4 ppb in urine

• 43 % used rubber gloves

7.9 ppb in urine

3.2 ppb mean for all farmers – application day

Glyphosate in urine (ppb)

Yes NoWore gloves when mixing 1.5 9.7Closed cab 2.0 6.5Mixing loading spill 7.3 2.7Application spill 9.2 2.5Observed skin contact 9.0 2.0Equipment repair 7.2 2.3

Glyphosate in urine (ppb)

Acres treated 10-44 45-124 125-439 2.9 2.9 3.8

No. of loads 1-2 3 4-6 7-121.2 2.9 3.8 10.7

Factors associated with INCREASE in urinary glyphosate when

gloves NOT used

More • Acres treated• Mixing / loading operations• Observed spills• Equipment repairs

Results – 78 children

• 9 (11%) had detectable levels of glyphosate- all from South Carolina

• 8 of 26 (31%) present during mixing or application had detectable levels

• Highest conc (29 ppb) in teenage boy most active in assisting with mixing and application

- father had highest urine conc (233)- had spills, spent long periods repairing

boom & smoked during repairs

Results – 48 spouses

• None participated in applications• 2 (4%) had detectable levels of glyphosate –

highest 3 ppb• 8 in immediate area of mixing and loading-

none had detectable levels• 40 (83%) washed applicators clothes during

study – 2 (5%) had detectable glyphosate levels (1 ppb)

Glyphosate exposure

• Maximum farmer dose was 0.004 mg/kg

• Average farmer dose was 0.0001 mg/kg

• EPA lowest no effect level set at 175 mg/kg/d

• Estimated daily oral exposure for life with no harmful effect – 2 mg/kg/d

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

• Use of rubber gloves when mixing, loading, and applying glyphosate was associated with greatly reduced urinary concentrations of glyphosate

• Little evidence of glyphosate exposure to family members not participating in or around exposures

• Increased loading, mixing, and repairs increases potential for exposure

• What would you add?

Reminders

• Glyphosate is not as likely to be absorbed through the skin or enter through the lungs as other pesticides used on the farm

• Glyphosate metabolism in the body may be very different than that for other pesticides

• This study points out factors that affect exposure – the effects will vary with other products