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March 23, 2021

This blog post was written by Arizona State University doctoral candidate and Swette Center for Sustainable Food Systems Research Associate Estève Giraud.

Arizona State University held the world’s largest scientific meeting for the annual conference of the American Association for the Advancement of Science (AAAS) from February 8 through 11, 2021 where the theme of the meeting focused on understanding dynamic ecosystems. Dr. Kathleen Merrigan, executive director of the Swette Center for Sustainable Food Systems at ASU, and Estève Giraud gave a presentation on Innovating Organic Agriculture for the occasion. The content of this talk is summarized below.

The Organic Food Production Act (OFPA) of 1990 celebrated its 30th birthday last November, and it has stood the test of time. The organic industry has grown to over $55 billion each year, with 16,585 organic farms in the U.S. Additionally, each year more American consumers purchase organic food, with health as a primary motive. In 2020, 82% of U.S. families had purchased organic food at least once in the year. While the organic industry has changed, the original law has not; the OFPA has remained unamended in the thirty years since it was passed.

Despite the growth, the organic industry still faces challenges. Organic mid-size operators struggle to thrive financially, even with the price premium that organic practices carries. There is also unrest over the strength of organic enforcement and inspections, long overdue rulemaking including the origin of livestock rule, and the withdrawal of the animal welfare rule (OLPP). These issues were addressed during the senate confirmation hearing of the Secretary of Agriculture Tom Vilsack on February 2, 2021.

Organic agriculture is generally perceived as having both health and environmental benefits. The California Certified Organic Farmers (CCOF) organization recently released a plan for the State of California to increase its organic farmland from 4% to 10% by 2030 to continue benefiting from the positive impacts of organic agriculture. At the national scale, developing such a plan to increase organic acreage by bringing together different USDA and government programs could have deep and positive impacts for climate and health. To encourage that approach, the Swette Center has been working with the Natural Resources Defense Council and Californians for Pesticide Reform on a report for organic agriculture that includes 46 recommendations for the President Joe Biden’s administration, the 46th president.

Shifting our diets and modes of food production has never been more pressing. According to a CDC national report, over 90% of the U.S. population has detectable concentration of pesticides in their urine and blood sample. This is particularly alarming because research shows that pesticide exposure can lead to many health issues, including ADHD, Alzheimer’s, asthma, birth defects,  cancer, dementia, endocrine system dysfunctions, obesity, Parkinson and reproductive dysfunctions (see examples of research listed at the end of this article). Diets are the leading cause of pesticide exposure, but environmental exposure is prevalent among farmworkers and their families who are among the most vulnerable to pesticides. Fetuses, infants, and children are particularly impacted because they have higher rates of food consumption per pound of body weight.

Even pesticide intake that is considered to be safe by the FDA and the EPA might actually be harmful, especially in light of recent research on the gut microbiome. Indeed, it has long been argued that the targeted pathway of pesticides on plants and pests does not exist in humans, making the impact on human health minimal. However, this claim fails to address the direct impact on the gut microbiome. For example, the herbicide glyphosate targets a key enzyme in the shikimate pathway – a metabolic route for the biosynthesis of aromatic amino acids in plants and organisms. This pathway is not found in animals, but it is commonly present in human gut bacteria and is responsible for linking the metabolism of carbohydrates to the biosynthesis of folates and aromatic amino acids. Comparative studies show almost no trace of antibiotics and pesticides in organically grown food compared to conventional, which supports the idea that organic food is safer to consume.The organic law prohibits a wide variety of harmful substances. A 2018 report by Misiewicz and Shade from the Organic Center shows that non-organic farming allows 900 synthetic pesticides for crop production, while organic farming only allows 25. The National Organic Program implements strict rules to protect human health. Controls for pesticide residues only allows for 5% of the FDA and EPA tolerance level for conventional agriculture. As a consequence, diet intervention experiments show that the adoption of an organic diet strictly reduces the pesticide urinary levels after only a week. Organic diets have also been linked to reduced risks of cancer, improved fertility outcomes, and reduced risks of diabetes. Additionally, organic food production reduces antibiotic resistance, nitrogen pollution and pesticide drifts, all of which are consequences of conventional agriculture and have public health and environmental impacts.

In 2018, agriculture was responsible for about 10% of the greenhouse gases (GHG) emissions in the United States, without including post-farmgate activities. Globally, the agricultural sector is a major contributor to climate change. However, organic agriculture tends to perform better in that regard, especially thanks to farming practices that promote healthy soils and enhance carbon sequestration. According to the 30 year Farming Systems Trial study of the Rodale institute, conventional agriculture produces 40% more GHG emissions per pound of crop than organic agriculture. For livestock, organic ruminants such as cows are required to have access to pasture, which supports their digestion, reduces their methane emissions, and improves the breakdown of manure. Organic farmers are required to detail their strategies to build soil organic matter as a part of their certification process.

Current discussions on the creation of soil carbon markets are reviving the debate over tillage. While tillage is practiced by many organic farmers, the advocates of no-till claim that tillage is detrimental to carbon sequestration. Although it is true that no-till does support carbon sequestration on the upper soil layer (0 to 5 cm), it is unclear if it supports carbon sequestration at the deeper soil levels, especially if no-till is combined with the use of synthetic pesticides as it is commonly the case in conventional no-till agriculture. In contrast, organic farming practices allow for deeper carbon sequestration, in particular because they enhance microbial and plant diversity, which supports carbon sequestration further beyond the surface. The growing research on regenerative agriculture is encouraging, as it reflects a wider and increasing concern for sustainable farming. However, as a recent article by Newton and colleagues points out, there is currently no clear definition of regenerative agriculture, which unfortunately allows the term to be used to qualify unsustainable farming practices.

More research on organic agriculture practices is needed. For example, research that connects the nutritional benefits of organic food with the quality of the soil microbiota and farming practices is an exciting area with a lot to explore. Research on integrated pest-management strategies, crop-livestock integration for carbon sequestration and the development of organic crop and animal for better resistance to climate change are all potential avenues to improve the state of organic science.

The talk evolved into a Q&A session between the participants and the presenters, and topics such as genetically modified organisms (GMOs), biosolids, manure, international organic standards and gut microbiome were addressed. If you would like to learn more about these, you can watch and re-watch the presentation here.

Below are examples of research linking pesticide exposure to health issues:


Reddington, R. et al. Incidence of male breast cancer in Scotland over a twenty-five-year period (1992-2017). Eur J Surg Oncol 46, 1546–1550 (2020).

Lerro, C. C. et al. Use of acetochlor and cancer incidence in the Agricultural Health Study. Int J Cancer 137, 1167–1175 (2015).

Boulanger, M. et al. Agricultural exposure and risk of bladder cancer in the AGRIculture and CANcer cohort. Int Arch Occup Environ Health 90, 169–178 (2017).

Rios, P. et al. Environmental exposures related to parental habits in the perinatal period and the risk of Wilms’ tumor in children. Cancer Epidemiol 66, 101706 (2020).

Kunkle, B., Bae, S., Singh, K. P. & Roy, D. Increased risk of childhood brain tumors among children whose parents had farm-related pesticide exposures during pregnancy. JP J Biostat 11, 89–101 (2014).

Birth defects

Inheritance of Pathologies and Sperm Epimutations: Generational Toxicology. Scientific Reports 9, 6372 (2019).


Shaffo, F. C., Grodzki, A. C., Schelegle, E. S. & Lein, P. J. The Organophosphorus Pesticide Chlorpyrifos Induces Sex-Specific Airway Hyperreactivity in Adult Rats. Toxicol Sci 165, 244–253 (2018).

Parkinson, Alzheimer's, brain degeneration

Pezzoli, G. & Cereda, E. Exposure to pesticides or solvents and risk of Parkinson disease. Neurology 80, 2035–2041 (2013).

Tang, B. L. Neuropathological Mechanisms Associated with Pesticides in Alzheimer’s Disease. Toxics 8, 21 (2020).

Su, F.-C. et al. Association of Environmental Toxins With Amyotrophic Lateral Sclerosis. JAMA Neurol 73, 803 (2016).

Pearson, B. L. et al. Identification of chemicals that mimic transcriptional changes associated with autism, brain aging and neurodegeneration. Nature Communications 7, 11173 (2016).

Aloizou, A.-M. et al. Pesticides, cognitive functions and dementia: A review. Toxicology Letters 326, 31–51 (2020).


Kaur, N. et al. Longitudinal association of biomarkers of pesticide exposure with cardiovascular disease risk factors in youth with diabetes. Environ. Res. 181, 108916 (2020).


Roberts, J. R., Dawley, E. H. & Reigart, J. R. Children’s low-level pesticide exposure and associations with autism and ADHD: a review. Pediatr Res 85, 234–241 (2019). Obesity

Simmons, A. L., Schlezinger, J. J. & Corkey, B. E. What Are We Putting in Our Food That Is Making Us Fat? Food Additives, Contaminants, and Other Putative Contributors to Obesity. Curr Obes Rep 3, 273–285 (2014).

Endocrine system dysfunction

Li, A. J., Chen, Z., Lin, T.-C., Buck Louis, G. M. & Kannan, K. Association of urinary metabolites of organophosphate and pyrethroid insecticides, and phenoxy herbicides with endometriosis. Environment International 136, 105456 (2020).