Exposure assessment using human biomonitoring for glyphosate and fluroxypyr users in amenity horticulture

Glyphosate in Irish adults - A pilot study in 2017

OBJECTIVES

Glyphosate is the highest volume herbicide used globally and has recently been classified as a 2 A 'probably carcinogenic to humans' by the International Agency for Research on Cancer (IARC). There is limited data to evaluate the public health impacts from glyphosate exposure. The objective of this study is to conduct an exploratory glyphosate exposure assessment study among Irish adults, who were non-occupational users of glyphosate.

STUDY DESIGN

A convenient sampling method was used, collecting one first morning void spot urine sample from each participant.

METHODS

A biomonitoring survey involving the collection and analysis of 20 ml spot urine samples from 50 Irish adults was conducted in June 2017. Participants completed a short questionnaire to collect information on demographics, dietary habits and lifestyle. Glyphosate was extracted using solid phase extraction (SPE) and analysed by liquid chromatography tandem mass spectrometry (LC-MC/MS).

RESULTS

Of the 50 urine samples analysed, 10 (20%) contained detectable levels of glyphosate (0.80-1.35 µg L-1). Exposure concentrations are higher than those reported in comparable studies of European and American adults.

CONCLUSIONS

Glyphosate was detectable in 20% of the samples collected from Irish adults. The low proportion of detectable glyphosate levels could be due to lower localised use of pesticides, having a small sample size or the higher analytical detection limit used in this study (0.5 µg L-1), which could underestimate the true exposure and warrants further investigation. Given the widespread use of glyphosate, further information on population exposure is required to advance our understanding of the relationship between chronic low dose exposure to glyphosate and human health risk.

Characterising glyphosate exposures among amenity horticulturists using multiple spot urine samples

BACKGROUND

Glyphosate has recently received much public attention following its 'Group 2A - probably carcinogenic to humans' classification from the International Agency for Research on Cancer. Despite the widespread use of glyphosate, there is limited data on potential exposures during common occupational uses.

OBJECTIVE

The study aimed to characterise occupational exposures to glyphosate among amenity horticulturists through the collection and analysis of urine samples following pesticide application. The impact of work practices on personal exposure, as well as suitability of collecting multiple spot urine samples as a sampling strategy for the assessment of occupational exposure for glyphosate were also examined.

METHODS

A minimum of three spot urine samples were collected per work task; before the work task began, after the work task completion and the following first morning void. All samples were analysed separately for glyphosate using liquid chromatography tandem mass spectrometry and for creatinine. Differences in urinary glyphosate concentrations between the pre-task samples versus the post-task and the peak urinary samples were both analysed using paired Student t-tests. Determinants of exposure on glyphosate urine concentrations were evaluated using Pearson's correlation coefficients and linear regression. A multivariate mixed effect model were elaborated to compare the glyphosate concentrations between post-task and following first morning void samples. In these models, worker identity was entered as a random effect to account for the presence of correlations between repeated measurements from the same individuals.

RESULTS

Peak urine glyphosate concentrations measured for work tasks were 2.5, 1.9, 1.9 and 7.4 μg L-1 (arithmetic mean, geometric mean, median and maximum value, respectively). Concentrations were highest in samples taken up to 3 h after completing the work task. Regression analysis showed that workers who sprayed the day before the sampling task had higher glyphosate concentrations in pre-task samples than those who did not spray the day before (p < 0.01). Similarly, workers who took breaks during the work task had higher peak urinary glyphosate concentrations (p < 0.01). The multivariate mixed effect model showed that the following first morning void samples were approximately a factor 0.7 lower than post-task values.

CONCLUSION

Occupational exposures to glyphosate among amenity horticulturalists are greater than those reported in environmental studies and comparable with previously reported agricultural studies. A suitable sampling strategy for occupational exposures to glyphosate is the collection of a spot urine sample up to 3 h after completing the application of a glyphosate based pesticide product, which provides a reliable marker of peak exposure.

Postnatal exposure to a glyphosate-based herbicide modifies mammary gland growth and development in Wistar male rats

Our aim was to evaluate whether postnatal exposure to a glyphosate-based herbicide (GBH) modifies mammary gland development in pre- and post-pubertal male rats. From postnatal day 1 (PND1) to PND7, male rats were injected subcutaneously every 48 h with either saline solution (vehicle) or 2 mg GBH/kg·bw. On PND21 and PND60, mammary gland and blood samples were collected. Estradiol (E2) and testosterone (T) serum levels, mammary gland histology, collagen fiber organization, mast cell infiltration, proliferation index, and estrogen (ESR1) and androgen receptor (AR) expression levels were evaluated. At PND21, GBH-exposed male rats exhibited greater development of the mammary gland with increased stromal collagen organization and terminal end buds (TEBs) compared to control rats. At PND60, the number of TEBs remained high and was accompanied by an increase in mast cell infiltration, proliferation and ESR1 expression in GBH-exposed male rats. In contrast, no effects were observed in E2 and T serum levels and AR expression in both days studied. Our results showed that a postnatal subacute treatment with GBH induces endocrine-disrupting effects in the male mammary gland in vivo, altering its normal development.