The Nuanced Question of Pesticides

By: Isabella Sferra
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Pesticides are part of an evolving narrative around environmental health and human safety that pose a problem with no simple solution. They’ve been in the environmental hot seat since Rachel Carson’s publication of Silent Spring and are likely to remain so for a long time coming. While they’ve helped enable greater harvests and increased food security for millions, there is a clear need for less harmful methods of pest management. Fortunately, there are things that gardeners and farmers can do to reduce the risk of pesticides to themselves and the environment.

First, what are pesticides? They encompass a wide variety of compounds and techniques for removing unwanted organisms from a garden or agricultural area. The National Pesticide Information Center (1), an excellent resource on pesticide use, provides a whole list of pesticides. These include insecticides, fungicides, herbicides, and rodenticides. Pesticides have helped enable the massive increase in food production we’ve seen over the last few decades. They were a part of the period known as the Green Revolution (2) in the 20th century and continue to help feed millions in both the developed and developing world.

Aside from solely using conventional pesticides, there are also newer, more innovative ways to control pests, like Integrated Pest Management. This approach uses a wide variety of pest-control methods to reduce harm to crops and toxicity to people and wildlife from conventional pesticide use.

The harms of pesticides, however, are likely to be pervasive, wide-ranging, and have no easy cure. Pesticides can sometimes stay in the environment for a long time- in this case, they’re considered persistent chemicals. This means that they can exert their harmful effects long after the initial application. There is also significant risk of harm to humans and wildlife, though research in this area is difficult due to the complexity and long-term nature of the issue. For example, a recent meta-analysis (3) examined the relationship between general pesticide exposure and cancer. They found credible evidence to support the recommendation that people reduce pesticide exposure for safety reasons related to cancer. 

On the wildlife end, the dangers are equally present. Researchers from the University of Arizona detail how (4) wildlife can be exposed to pesticides through ingestion or eating animals that have been exposed enough to have pesticides in their bodies. This can kill them or affect their fertility and behavior. Pelleted snail bait, for example, can easily be mistaken by both pets and wildlife for food and could be toxic or even deadly. The University of Georgia’s Honey Bee program (5), another great resource for people looking to understand more about the important role bees play in agriculture, describes the damage pesticides can do to bees. They indicate that bees can be killed just by being in contact with plants that have been sprayed with pesticides. The bees can bring the pesticide into the hive, where its effects spread and can destroy colonies. Another article (6) found that certain kinds of pesticides- in this case, insecticides and herbicides- was correlated with lower butterfly populations in a large study of French gardens.

Here are some ways to reduce harm from pesticides in your garden:
·   For localized bug infestations, remove by hand when possible
·   Remove sources of standing water to reduce mosquito infestations
·   A recent study (7) found that planting marigolds can help reduce infestations of glasshouse whiteflies on tomato plants
·   New Jersey’s Pesticide Control Program also asserts (8) that garlic and basil can also serve as a deterrent for some common pests, along with a host of other inventive solutions to check out
·   Per the University of Georgia’s Honey Bee program, spray pesticides in the evening, to reduce chance of contact with bees
·   A recent article (9) from Fine Gardening describes how farmers and gardeners can encourage birds to act as natural insect controllers by providing food and habitat
·   Lay down a layer of mulch or plant thick groundcovers in open areas to smother weeds- but make sure the groundcover isn’t invasive first
·   The Penn State Extension program (10) describes some physical methods like sticky traps for insects, as well as allowing minor levels of infestation in addition to some other helpful methods that are worth a look

On the other hand, I think it’s important to acknowledge the complexity of the issue. When we’re talking about who should be using pesticides and when, it’s easy to forget that not everyone is in the same situation. For example, should a farmer in a developing country sacrifice a larger harvest- which could ensure that more people have food and help develop the economy- to avoid using conventional pesticides? Should developing countries completely cease use of DDT, even if it can help control malaria (11) in some circumstances? Should large farm owners in more developed countries go entirely organic, even if it means that the poor have even less access (12) to fresh fruits and vegetables (13) due to lower yields? People having discussions and taking action about pesticides should consider the tradeoffs and who could be hurt by their choices to use or not use these chemicals.
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Maybe this is a situation where governments need to come in and subsidize or otherwise incentivize more costly pest-management methods as well as access to fresh produce. More research needs to be done on safer pesticides, and how to more safely apply the ones we have now. Still, there’s power in the ability of the individual gardener to reduce or change their pesticide use. While the individual impact of such a change is small, the collective effect could be very large. In a time where we have so little control over what’s going on in the environment around us, that means a lot.

Sources
1.  Pesticides and Human Health. (2019, May 14). Retrieved July 10, 2020, from http://npic.orst.edu/health/humhealth.html
2.  Pingali, P. L. (2012). Green Revolution: Impacts, limits, and the path ahead. Proceedings of the National Academy of Sciences, 109(31), 12302-12308. doi:10.1073/pnas.0912953109
3.  Bassil, K. L., Vakil, C., Sanborn, M., Cole, D. C., Kaur, J. S., & Kerr, K. J. (2007). Cancer health effects of pesticides: systematic review. Canadian family physician Medecin de famille canadien, 53(10), 1704–
4.  Dolan, C., & Mannan, B. (2009, October). Pesticide Use and Wildlife. Retrieved from https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1481i.pdf
5.  Bees, Beekeeping, & Protecting Pollinators. (n.d.). Retrieved July 10, 2020, from https://bees.caes.uga.edu/bees-beekeeping-pollination/pollination/pollination-protecting-pollinators-from-pesticides.html
6.  Muratet, A., & Fontaine, B. (2015). Contrasting impacts of pesticides on butterflies and bumblebees in private gardens in France. Biological Conservation, 182, 148-154. doi:10.1016/j.biocon.2014.11.045
7.  Conboy, N. J., Mcdaniel, T., Ormerod, A., George, D., Gatehouse, A. M., Wharton, E., . . . Tosh, C. R. (2019). Companion planting with French marigolds protects tomato plants from glasshouse whiteflies through the emission of airborne limonene. Plos One, 14(3). doi:10.1371/journal.pone.0213071
8.  Waters, A. (n.d.). Alternatives to Pesticides. Retrieved from https://www.state.nj.us/dep/enforcement/pcp/administration/alternative.pdf
9.  Keep Beneficial Insects, Birds and Mammals Around By Creating a Host Environment. (2012, December 28). Retrieved July 10, 2020, from https://www.finegardening.com/article/keep-beneficial-insects-birds-and-mammals-around-by-creating-a-host-environment
10.   Pesticides and Alternatives. (2014, September 2). Retrieved July 10, 2020, from https://extension.psu.edu/pesticides-and-alternatives
11.   Bouwman, H., Berg, H. V., & Kylin, H. (2011). DDT and Malaria Prevention: Addressing the Paradox. Environmental Health Perspectives, 119(6), 744-747. doi:10.1289/ehp.1002127
12.   Dwyer, M. (2014, January 13). Eating healthy vs. unhealthy diet costs about $1.50 more per day. Retrieved July 10, 2020, from https://www.hsph.harvard.edu/news/press-releases/healthy-vs-unhealthy-diet-costs-1-50-more/
13.   Savage, S. (2019, January 01). USDA data confirm organic yields significantly lower than with conventional farming. Retrieved July 10, 2020, from https://geneticliteracyproject.org/2018/02/16/usda-data-confirm-organic-yields-dramatically-lower-conventional-farming/