Characterising occupational exposure to glyphosate among amenity horticulturists
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Date
2018-12-19Author
Connolly, Alison
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Abstract
A dearth of knowledge exists regarding occupational glyphosate exposures among
amenity horticulturalists. Glyphosate is the highest volume herbicide used globally,
and has recently been classified by the International Agency for Research on Cancer
as a 2A 'probably carcinogenic to humans’. The objective of this study was to
characterise glyphosate exposures and identify exposure determinants among amenity
horticulturists.
Human biomonitoring assessments were completed by collecting spot urine samples
from workers. In parallel, a dermal and inadvertent ingestion study was completed by
collecting wipe samples of the worker’s hands and perioral region and by analysing
samples of worker gloves. Samples were analysed using liquid chromatography
tandem mass spectrometry (LC-MS/MS). Linear mixed effect regression models were
constructed to evaluate determinants of dermal, inadvertent ingestion and total
glyphosate exposure.
A total of 205 urine samples and 351 wipe and glove samples were collected and
analysed for glyphosate across 69 work tasks involving the glyphosate based pesticide
products. Glyphosate concentrations ranged from below the limit of quantification to
10.66 μg L−1; the human biological half-life was estimated to be 5 ½ to 10 hours. Peak
exposure levels were identified in urine samples collected up to three hours after
cessation of the pesticide task. A forward built mixed effect model including sampling
time, participant age and application type explained 62% of the variability in worker
hand glyphosate concentrations. In the inadvertent ingestion exposure model the
determinants hand contamination, the frequency of hand to mouth and surrounding
area contact and sampling time explained 50% of the variability in perioral
concentration. Combined hand and perioral region concentrations explained 40% of
the variability in the urinary glyphosate concentrations (μg L-1).
Occupational glyphosate exposures among amenity horticulturalists are higher than
expected from environmental exposure alone and comparable with agricultural
studies. New information is reported on the human biological half-life of glyphosate.