Human Oral Buccal Microbiomes Are Associated with Farmworker Status And Azinphos-methyl Agricultural Pesticide Exposure.

Publication Type:

Journal Article


Applied and environmental microbiology (2016)


In a longitudinal agricultural community cohort sampling of 65 farmworker and 52 non-farmworker adults, we investigated agricultural pesticide exposure associated changes in the oral buccal microbiota. We found a seasonally persistent association between the detected blood concentration of the insecticide Azinphos-methyl and the taxonomic composition of the buccal swab oral microbiome. Blood and buccal samples were collected concurrently from individual subjects in two seasons, spring/summer 2005 and winter 2006. Mass spectrometry quantified blood concentrations of the organophosphate insecticide Azinphos-methyl. Buccal oral microbiome samples were 16S rRNA gene DNA sequenced, assigned to the bacterial taxonomy and analyzed after 'centered-log-ratio' transformation to handle the compositional nature of the proportional abundances of bacteria per sample. Non-parametric analysis of the transformed microbiome data for individuals with and without Azinphos-methyl blood detection showed significant perturbations in seven common bacterial genera (>0.5% of sample mean read depth), including significant reductions in the common oral bacteria, Streptococcus Diversity in 'centered-log-ratio' composition between individuals' microbiomes was also investigated using principal components analysis (PCA) to reveal two primary PCA clusters of microbiome types. The spring/summer 'exposed' microbiome cluster with significantly less bacterial diversity was enriched for farmworkers and contained 27 of the 30 individuals who also had Azinphos-methyl agricultural pesticide exposure detected in the blood.

IMPORTANCE: In this study we show in human subjects that organophosphate pesticide exposure is associated with large-scale significant alterations of the oral buccal microbiota composition with extinctions of whole genera suggested in some individuals. Persistence from the spring/summer to the winter of this association also suggests long lasting effects on the commensal microbiota have occurred. The important health related outcomes of these agricultural community individuals' pesticide associated microbiome perturbations are not understood at this time. Future investigations should index medical and dental records for common and chronic diseases that may be interactively caused from this pesticide exposure-microbiome alteration association.