Pesticides are Poison: Is Organic Farming “Safer” for Workers than Traditional Farming?

It is well known that chemical pesticides, fungicides, and herbicides can be harmful to the environment as well as the people exposed to these compounds.  For example, certain fungicides used in grape growing have been shown to be linked to increased risk of thyroid cancer to those exposed to the chemical (more here).  Additionally, pesticides have been shown to drift from vineyards in South Africa into the air, soil, and water around a primary school where children frequently play outside and risk harm from long-term exposure of the chemicals (more here).

In terms of environmental impact, studies have shown many positive effects of organic farming.  For example, some studies have found that organic viticulture methods have positive effects on the microbial

Photo By Verita (Own work) [GFDL ( or CC-BY-3.0 (], via Wikimedia Commons

Photo By Verita (Own work) [GFDL ( or CC-BY-3.0 (], via Wikimedia Commons

population of the vineyards, allowing for a more natural bio-control of unwanted organisms instead of using a chemical arsenal of products (more here).   Also, organic viticulture techniques have been shown to increase the quality of the soil over time compared with conventional methods (more here).

In terms of whether or not wine made from organically-grown grapes is higher quality compared with grapes grown under traditional/conventional viticultural methods, the jury is still out.  While harmful pesticide or fungicide residues are reduced in organic wines, in terms of polyphenol content of wines, studies haven’t been able to show with any consistency that there are any differences among organically and conventionally grown grapes (more here).

While some pesticides have been banned by various countries, there are still many that are allowed to be utilized in traditional farming that have been shown to increase risk of cancer, cause reproductive problems, and cause many health troubles associated with endocrine-disrupting chemicals.

Based on many environmental studies, organic farming is assumed to be more desirable that conventional farming in terms of overall environmental health (soil, plant life, etc).  However, while there have been a spattering of studies here and there focusing on human health, much less is known regarding the direct comparison between organic farming and traditional or conventional farming related to pesticide exposure and consequences on human health.  This lack of knowledge led some researchers in a recent study to examine the genetic and immunological changes in both organic and conventional farm workers.  In other words, they sought determine if one method is “safer” than the other in terms of immune system effects as well as possible genetic predisposition to greater harm related to pesticide exposure.

The who, what, and how:

While the groups were somewhat skewed in terms of numbers of individuals per group, this study focused on individuals practicing conventional farming methods with pesticide exposure for a minimum of four months as well as individuals practicing certified organic farming methods for a minimum of four months.  As a control group, people that practiced neither conventional nor organic farming methods were recruited.  All participants were from the Oporto region of Portugal.

The researchers collected a lot of information from the participants, including age, race, sex, smoking

Photo By Jeanne Kelly [Public domain or Public domain], via Wikimedia Commons

Photo By Jeanne Kelly [Public domain or Public domain], via Wikimedia Commons

history, and many other demographics statistics. Additionally, those that were exposed to pesticides were asked how long it’s been since they were exposed (most were within a couple of days), and what type of exposure did they experience.  Were they in charge of mixing together the formulas?  Were they responsible for the application of the pesticides?  All routes of exposure were identified and taken in consideration for the analysis.

Pesticides were measured in both blood and in urine of each participant and were collected in the morning for an entire year period.

Pesticides were grouped into four different classes: pyrethoids, carbamates, organophosphates, and “other”.  In addition to pesticide levels in blood and urine, participants were also screened for chromosome abnormalities, as well as lymphocyte levels (white blood cells associated with immune system reactions).  Finally, genetic analysis were performed on each participant to determine if certain genotypes were more susceptible to harmful effects induced by pesticides or not.

So, what’d they find?

  • Compared with the non-exposed control group, those participants exposed to pesticides in conventional farming practices had elevated levels of lymphocytes, chromosome abnormalities, and DNA damage.
  • B-lymphocytes were decreased in organic farmers compared with control participants, indicating a decrease in immunosuppression caused by an associated decrease in antibodies (what B-lymphocytes create) and a weakened immune system.
  • Despite the decrease in B-lymphocytes, organic farmers in general expressed very similar levels of genetic damage as the unexposed control group of individuals.
  • The exact role each conventional farmer played in regards to handling the pesticides made a huge difference in terms of exposure.  Specifically, those farmers actually applying the pesticides to the field suffered from greater immune system and genetic damage than those handling the pesticides in other ways (such as mixing or loading).  Even more telling was that these harmful effects were even greater when the individual did not handle the pesticides properly.
  • Lymphocyte levels in conventional farmers were lowest during the spring-to-summer portion of the year, which is not surprising considering this is the time of year that pesticide applications and exposures were the greatest.
  • When comparing working in a greenhouse versus working in an open field, those exposed to pesticides in a greenhouse suffered even greater damaging effects than those exposed to pesticides in an open field.  This is not all that surprising to me, considering a greenhouse is a mostly closed environment while the open field is subject to significant air movement and dissipation of the harmful chemicals in the immediate vicinity of the applicator.
  • In terms of genetic damage, those individuals that were positive for the GSTM1 and GSTT1 genes suffered from greater genetic damage than those that were negative for the genes.  Specific lymphocytes called “natural killer cells” (aids in immune response) were also decreased in individuals who were GSTM1 positive.  Individuals who were positive for the gene GSTP1 105Val/Val suffered from less damage than those that were negative for this gene.

Concluding thoughts…

Despite the limitation of having unbalanced numbers of individuals per group (85 conventional farmers, 36 organic farmers, and 61 non-exposed controls), the main results of this study were interesting in it seemed to show that those exposed to pesticides used in conventional farming appear to have a more damaged or more compromised immune system than those practicing organic farming or the unexposed controls.

These results should be taken with a grain of salt; however, as 1) the group sizes were markedly different and 2) how are we to know that the differences in immune system and genetic health aren’t different between groups for other reasons?  Perhaps those practicing organic farming also practice a healthier lifestyle in general compared with conventional farmers.  Perhaps there are other confounding factors that need to be taken into account.  Perhaps we’ll still see similar results after controlling for these factors, but we need to check to be certain.

It was also interesting to note that even the immune systems of organic farmers were “better” than conventional farmers (specifically noting B-lymphocyte level decreases), even the organic farmers had B-lymphocyte levels that were lower than the controls. What is causing this damage if not the pesticides?

Photo from Wikimedia.  This media is available in the holdings of the National Archives and Records Administration, cataloged under the ARC Identifier (National Archives Identifier) 555264.

Photo from Wikimedia. This media is available in the holdings of the National Archives and Records Administration, cataloged under the ARC Identifier (National Archives Identifier) 555264.

There must be something else going on here that causes some immune system and genetic damage even among the organic farmers (albeit not as much damage as the conventional farmers).

In general, I think this concept is an interesting one and I would not be terribly surprised if these results were able to be repeated with greater and more balanced sample groups.  With all the harm to the environment that are known to be associated with pesticide exposure, why would it be any different for the humans that are exposed to the chemicals as well?

More research is certainly needed to provide support for (or refute) the results in this study, but for now, if you are practicing conventional farming, at the very least please follow the instructions for application of the pesticides very carefully and be sure anyone handling the chemicals are properly trained.  If this study gives us any indication, carelessness in pesticide applications result in even greater damage to one’s immune system and genetic structure than if one was to apply the pesticides as instructed.

What do you all think of this study?  Do you have any experience with this topic?  What other things would you like to have seen done in this study to be more convincing (or not)?  Please feel free to leave any questions or comments that you may have.  Cheers!

Primary Source: Costa, C., García-Lestón, J., Costa, S., Coelho, P., Silva, S., Pingarilho, M., Valdiglesias, V. Mattei, F., Dall’Armi, V., Bonassi, S., Laffon, B., Snawder, J., and Teixeria, J.P. 2014. Is organic farming safer to farmers’ health? A comparison between organic and traditional farming. Toxicology Letters.

8 comments for “Pesticides are Poison: Is Organic Farming “Safer” for Workers than Traditional Farming?

  1. Derek
    April 22, 2014 at 3:38 pm

    I think it should be noted that your article makes a very common mistake. It seems to referring to Pesticides vs. Organic. This distinction simply does not exist. ALL farming use Pesticides to some level or another. There are Organic Pesticides and Non-Organic/conventional Pesticides. Pesticide only means a product which kills or inhibits a pest. That pest could an insect, fungus, or bacteria.

    Also this article seems to be about general organic vs. conventional farming, not necessarily viticulture. I happen to farm vineyards which are conventional and Organic (some certified, some not). In our case the only “DANGER” labeled chemicals that we use, those are the ones that require a full face respirator and chemical suit, are OMRI approved Organic pesticides. Non of the conventional pesticides that we use require that level of safety precaution.

    • Becca
      April 22, 2014 at 8:19 pm

      Hi Derek! Thanks for your comments. You’re right, I should have added the word “conventional” a little more frequently instead of assuming it would be implied. I suppose with the sheer numbers and types of chemicals (both organic and conventional), it would have been more clear to toss in the appropriate adjective instead of just assuming my readers would know that is, in fact, what I meant.0

      Glad to hear that you are using pesticides that are relatively benign in terms of their danger levels! Thanks for your great insights!

  2. April 22, 2014 at 6:57 pm

    I farmed my vineyard organically for 4 years, but things have changed since the Organic Farm Production Act of 1990 setting up the National Organic Program. The organic program uses harsher chemicals. Look at the Cornell devised Environmental Impact ( EIQ) of organic products- they are worse than Roundup which has an EIQ of 15.3 . Organic product EIQs: insecticidal soap (19), horticultural oil (27.5), pyrethrin (39), sulfur (45.5) and Bordeaux mix (67.67). I turned to sustainable farming to avoid these organic products that are used because they are deemed “natural “. The concept of “natural ” appears to be unscientific and more like pseudoscience. I use the extensive environmental review of EIQ rather than concepts of “natural”. I turned to Certified Sustainable by SIP. Here’s what the everyone needs to know: both systems use pesticides. The organic pesticides I used in that system required 24 hours before re-entry into the vineyard. The new SIP approved synthetic pesticides require 4-6 hours before re-entry into the vineyard. Which do you think are safer for people? We need awareness that SIP sustainable products have lower EIQs and are safer than those under the organic program. Both systems use compost to improve our soils and cover crops to protect soils. So soil care is about the same, with less copper under SIP and one pass every 21 days under SIP but a pass through the vineyard every 7 days often for organic. This article comparing conventional farming to organic is not helpful to the many of us California vignerons who moved past “conventional” farming years ago. It’s time we update organic farming to be kinder to the environment or leave it behind too.

    • Becca
      April 22, 2014 at 8:20 pm

      Thanks for all your great comments, John! You’re right, there are a lot of folks that have moved past “conventional” farming, however at the same time, there are still a lot that have not. While some of my readers are already well familiar with this topic, I still feel as though it is valuable for those readers that have not yet moved toward more organic or sustainable farming practices.

      So great to hear about your own personal experiences! Thank you for sharing!

      • April 28, 2014 at 2:22 am

        I echo John’s comments, and add that far from being good for the soil, “organic” viticulture has poisoned thousands of hectares of French vineyards through the use of Bordeaux mixture, which contains a toxic, persistent heavy metal. Organic and its unnatural cousin biodynamic also deny adherents the use natural, soil improving preparations like Rhizobial bacteria and beneficial fungi like Trichoderma. Finally, very very few vineyard managers in their right mind would use hard insecticides like those in two your groups, namely, carbamates, and organophosphates. So I am not sure how applicable the findings are to viticulture. Also, were they tested for heavy metal residues? This is probably the key issue with vineyard chemicals.

  3. Tom
    April 23, 2014 at 10:51 am

    Hi Becca,

    Great summary! I worked in enviro advocacy for many years and we would have been grateful for data even as moderately good as these are (they have many limitations, as you point out).

    I wonder if the baseline B-lymphocyte decrease might be due to PM2.5 exposure — in other words, dust from the fields. Organic farming or no, soil is filled with heavy metals and micro-organisms. Diesel particulate emissions might be another explanation.

  4. Marco
    April 28, 2014 at 2:20 am

    I agree with Derek and we have also to think that we all are producing and selling a dangerous substance: wine ! Wine contains alcohol. If we look at the intrinsic hazard of alcohol we shouldn’t drink any glass of wine !
    People using pesticides (synthetic or natural) have to handle it with all the attention (wearing mask, gloves and other protection clothes and devices) and avoid drift and contamination of water.
    The use of pesticides can be as safe as the use of drugs.

  5. Emma B
    May 5, 2014 at 12:19 pm

    Sulphur and copper (which ARE chemicals, just not synthetic products) are used far more in organic viticulture than conventional / IPM systems, which have more fungicides available against mildews. So it’s pretty hard to argue that organic viticulture is going to be healthier for the viticulturist than non-organic, given its dependence on two chemicals which would be very unlikely to get approval for use if they were submitted as new products, not least because of their environmental impact on other life forms.

    Unfortunately both will continue to be used in viticulture for the foreseeable future, as they’re multi-site fungicides, i.e. the risk of resistance development is very low. (Single-site = only one line of attack by the pesticide but very powerful until resistance develops at which point they’re almost useless, multi-site = multiple less strong lines of attack, but very hard for resistance to develop against everything simultaneously).

    The safest way to apply them is to limit their need by sensible vine management techniques, and to follow H&S procedures once professionally qualified to use them. But that goes for all pesticides, in all crops, no matter what approach the farmer has to pest control…

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