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Is organic farming safer?

Researchers from Portugal, Spain, Italy and the USA have worked in collaboration to compare the health of organic farmers with those using traditional farming methods (which typically involve pesticide use). 

The harmful properties of pesticides have been described extensively over the last few decades and, because of their widespread distribution, exposure to these compounds is a public health concern.   However, there is a limited amount of data on the genotoxic effect of pesticides to humans, so the researchers decided to investigate this.   

Recently, organic farming has become popular and there is a widespread belief that organic agricultural systems are friendlier to the environment and the consumer, than traditional farming systems, although little is known about the effects on farm workers' health. 

The aim of this work was to evaluate genetic damage and immunological alterations in workers of both traditional and organic farming. A multi-stage approach was used in order to integrate information obtained with biomarkers of exposure, effect and susceptibility.  The study involved: 85 farmers exposed to several pesticides, 36 organic farmers and 61 control subjects.

Biomarkers of exposure were as follows:
pyrethroids, organophosphates, carbamates, and thioethers in urine
butyrylcholinesterase activity in plasma

Biomarkers of early effect were:
micronuclei in lymphocytes and reticulocytes
T-cell receptor mutation assay
chromosomal aberrations
comet assay
lymphocytes subpopulations

And finally, biomarkers of susceptibility were:
genetic polymorphisms related to metabolism - EPHX1, GSTM1, GSTT1 and GSTP1
DNA repair-XRCC1 and XRCC2

Full experimental information can be seen in the publication.  Here, we describe how the investigators performed the comet assay: The alkaline comet assay was performed and each slide contained two experimental replicates from each donor. The slides were coded and examined by a ‘blind’ scorer.  One hundred randomly selected cells (50 per replicate) were examined from each subject. Image capture and analysis were performed with Comet Assay IV software (Perceptive Instruments).  The reported DNA damage parameter was percentage tail DNA. 

When compared to controls and organic farmers, farmers exposed to pesticides presented a significant increase of micronuclei in lymphocytes and reticulocytes, chromosomal aberrations, DNA damage assessed by comet assay, and a significant decrease in the proportion of B lymphocytes.

The data suggest there is an increased presence of DNA damage in farmers exposed to pesticides when compared to organic farmers.  The investigators also concluded that the exact nature of the exposure conditions may influence observed effects and that the health status of farm workers may be influenced by the type of agriculture they practice.

The scientists involved with the study stress that the findings reported here need to be interpreted with caution.  They suggest that due to the small size of the sample and the unbalanced distribution of individuals in the three study groups, further investigation of these conclusions would be appropriate.

Read more:
Costa, C., et al., Is organic farming safer to farmers health? A comparison between organic and traditional farming. Toxicol. Lett. (2014).