Follicular DNA Damage and Pesticide Exposure Among Latinx Children in Rural and Urban Communities

Introduction

Children in rural communities have greater exposure to pesticides than the general population. Long-term effects are difficult to assess and are poorly understood but are thought to increase incidence of cancer, asthma and cognitive deficits. In this paper the authors measured pesticide levels using silicone wristbands and correlated this with DNA damage quantified within epithelial cells of plucked hair follicles from chidren living in both rural and urban communities.

Main Points

• 30 latinx children aged 10-12 from rural communities and 15 from urban communities wore a silicone wristband, containing membranes that adsorb a large range of organic chemicals, for 6-17 days which were then tested for levels of 72 pesticides or their degradation products by gas chromatography.
• 5-10 scalp hairs were collected from the same children, fixed in 4% formaldehyde for 20 mins, before the whole mount hairs were immunofluorescently labelled for gH2AX (DNA damage) and 53BP1 (DNA damage repair). The number of labelled cells were then visually quantified.
• Pesticides were detected in the wristbands of 43/45 participants. The number of pesticides detected in the rural and urban cohorts were similar but the class of compound was different, with more organochlorine pesticides in urban participants compared to rural, and more organophosphate pesticide detections in the rural than in the urban group.
• Children in the rural group had significantly more DNA damage in the hair bulbs than the urban group.
• Highest levels of DNA damage were seen when hairs were sampled in April – June and the lowest in October-November, which was expected as there is greater sun exposure and hence possible UV damage in the spring / summer months.
• When DNA damage levels in the two groups were compared over a similar summertime period (July–September) there were higher levels in children in the rural group, indicating that the difference between the two groups was not caused by seasonal effects.

Conclusion

The results point to rural disparities in pesticide exposures and their outcomes in children from Latinx communities. They suggest that among the different classes of pesticides, organophosphates have the strongest genotoxic effects. Assessing pesticide exposures and their consequences is key to environmental surveillance programs and the approach used here is particularly well-suited for children.

EPISTEM SERVICES

Histology and IHC

This data supports the use of hair follicles to monitor the biological effects of exposure to toxic agents. Epistem have pioneered the use of the hair follicle to measure DNA damage, protein or RNA changes induced by chemotherapy, or other agents, in preclinical and clinical situations.

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Biomarker discovery

In pre-clinical POC models freshly plucked hairs can be maintained ex vivo in the presence of Test Articles and effects on protein or RNA measured. Biomarkers characteristic of target engagement can be identified. Hairs collected during clinical trials can similarly be analysed. Pharmacodynamic (PD) biomarker responses can be correlated with PK.

Analytical services include quantification of IHC labelled hair sections (e.g. gH2AX, pChk1) either manually or semi-automated using the Aperio Scanscope CS2.

The team have a wealth of experience in developing and troubleshooting IHC protocols for both automated (Ventana Discovery Ultra) and manual applications.

Organoids

Epistem also offers organoid models of intestinal toxicity.

Laser Capture Microdissection

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