In preparation for an upcoming talk, I thought it would be a good idea to check in on the latest scientific research regarding agricultural chemicals and our health. I did extensive research for Organic Manifesto, but that was published in 2009, so it was time for an update based on more recent scientific studies.
Therefore, I turned to my trusty research expert, Diana Erney, whose office is two doors down from mine. She has access to the Rodale Library (as all Rodale employees do!), which is an amazing source of all sorts of interesting data.
Rather than pontificate on all the amazing research she dug up, I decided the best thing I could do is share it with all of you and let you become the pontificators. The studies listed below, unlike lots of writings on the Internet that may or may not be vetted, have passed the Rodale and Diana’s editorial filter of credible investigations, and all involved respectable and fairly bulletproof research. Where she has concerns about it (in one case, because of a very small sample size), I have left her cautions in. I’ve also included links to the studies in case you want to read deeper.
This is not “easy reading” or light blog fare—this is science, people! Yes, it’s dense, but it’s a great tool—and also a way to appreciate what our editors at Rodale sift through daily in order to translate research into easily digestible articles. This is pure fiber. (And, by the way, recent studies show that fiber is good for you.)
If you don’t have the will to navigate this type of research, here are the headlines in one clump:
- Organic foods have higher antioxidants, lower cadmium levels, and—as you would hope—lower pesticide residues.
- Eating organic eliminates most pesticide exposures.
- Fruit flies that eat organic foods are more fertile and live longer.
- Exposure to pesticides at work increases your risk of Alzheimer’s disease.
- Women who live on farms in Iowa have an increased risk for acute myeloid leukemia.
- Two more studies link pesticide exposures to autism.
- Pesticides are linked to an increase in food allergies.
And a special call-out to glyphosate, the active ingredient in Roundup, which sparks the heart of the controversy over genetically modified organisms—that GMOs are modified to enable more applications of Roundup:
- When tested in the combination of chemicals included, Roundup is one of the most toxic insecticides and herbicides on the market and is toxic to human cells.
- In 2013, the Environmental Protection Agency raised the allowable limits of glyphosate in foods.
- The Food and Drug Administration does not currently test for glyphosate levels in food, nor does the agency currently have the technology to do so.
The Good News about Organic and Health:
1. “Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops.”
“In the present study, we carried out meta-analyses based on 343 peer-reviewed publications that indicate statistically significant and meaningful differences in composition between organic and non-organic crops/crop-based foods. Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17, 86) % higher, respectively. Many of these compounds have previously been linked to a reduced risk of chronic diseases, including CVD [cardiovascular disease] and neurodegenerative diseases and certain cancers, in dietary intervention and epidemiological studies.
“Additionally, the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cd [cadmium]. Significant differences were also detected for some other (e.g. minerals and vitamins) compounds…
“In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.”
- Link to text: ncbi.nlm.nih.gov/pmc/articles/PMC4141693/
2. “Eating Mostly Organic Eliminates Most Pesticide Exposure.”
“Researchers had 13 people [Diana’s note: It’s important to mention that this is a very small study. However, it supports results previously found in larger studies in children.] to eat a diet of at least 80% organic food (diet logs showed 83% certified organic food and 10% probably organic food) or a non‑organic diet for a week and then the other diet for a second week. Urine samples were collected at the end of each week.
“Urinary levels of six dialkylphosphate metabolites (breakdown products of organophosphate pesticides) were compared between the samples and were found to be an average of 89% lower following the organic week than following the conventional week. Larger, longer studies should now be conducted to confirm these findings. ”
- Link to abstract: sciencedirect.com/science/article/pii/S001393511400067X
And my personal favorite:
3. “Fruit Flies Eating Organic Diets Are More Fertile, Live Longer.”
“Studying the effects of eating a particular food or diet is time consuming and inexact in humans, so researchers often turn to lab animals with short life cycles for help.
“In this study researchers used fruit flies (Drosophila melanogaster) to compare the possible effects of a conventional or organic diet on fertility and longevity. Diets were prepared using extracts of either conventionally or organically raised produce (bananas, potatoes, raisins, and soy beans—one food per diet) all purchased from a local supermarket.
“Flies fed most of the diets made from organically grown produce exhibited greater fertility and longevity than flies raised on the same diets made from conventionally grown produce. Some of the organic diets also appeared to increase fly activity and stress resistance.”
The researchers say this study shows that fruit flies can be useful tools for assessing the effects of diets as well providing concrete data that organic food is better for you. They don’t, however, know why or how the organic diets produced the observed results…allowing scope for further research.
- Link to full text: plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0052988
The Bad News about Chemicals and Health:
1. “Occupational pesticide exposures are associated with Alzheimer’s disease.”
“Previously, we reported that serum levels of dichlorodiphenyldichloroethylene (DDE), the metabolite of the pesticide dichlorodiphenyltrichloroethane (DDT), were elevated in a small number of patients with AD [Alzheimer’s disease]…
“Conclusions and Relevance: Elevated serum DDE levels are associated with an increased risk for AD and carriers of an APOE4 ε4 allele [NOTE: A genetic variant.] may be more susceptible to the effects of DDE. Both DDT and DDE increase amyloid precursor protein levels, providing mechanistic plausibility for the association of DDE exposure with AD. Identifying people who have elevated levels of DDE and carry an APOE ε4 allele may lead to early identification of some cases of AD.
“Importance: The causes of late-onset Alzheimer disease (AD) are not yet understood but likely include a combination of genetic, environmental, and lifestyle factors. Limited epidemiological studies suggest that occupational pesticide exposures are associated with AD.”
- Link to abstract: ncbi.nlm.nih.gov/pubmed/24473795
- Link to full text: ncbi.nlm.nih.gov/pmc/articles/PMC4132934
2. “Farm residence and lymphohematopoietic cancers in the Iowa Women’s Health Study.”
“Conclusions: Iowa women living on a farm or in a rural area were at increased risk of developing AML [acute myeloid leukemia], which was not related to crop acreage near the home. Living near pasture or row crops may confer an increased risk of CLL/SLL [chronic lymphocytic leukemia/small lymphocytic lymphoma] regardless of residence location.”
Link to abstract: www.ncbi.nlm.nih.gov/pubmed/25038451
3. “Study Supports Link Between Pesticides, Autism Spectrum Disorder” (ASD)
“Proximity to organophosphates at some point during gestation was associated with a 60% increased risk for ASD [autism spectrum disorder], higher for third-trimester exposures, and second-trimester chlorpyrifos applications. Children of mothers residing near pyrethroid insecticide applications just before conception or during third trimester were at greater risk for both ASD and DD [developmental delay], with ORs [odds ratio] ranging from 1.7 to 2.3.”
- Link to full text: http://ehp.niehs.nih.gov/wp-content/uploads/122/10/ehp.1307044.alt.pdf
4. “Potential mechanisms linking pesticides and autism.”
“Using exposure estimates from a historical pesticide use database, a study of mothers living in the California Central Valley showed that children born to mothers who had been exposed to organochlorine (OC) insecticides that were agriculturally applied within 500 m of the home between gestational days (GD) 26 and 81 (during neural tube closure) were 7.6 times more likely to be diagnosed with ASD add [autism spectrum disorder] than the children of mothers who lived in the lowest exposure quartile…”
- Link to full text: http://ehp.niehs.nih.gov/1104553/
5. “Dichlorophenol-containing pesticides and allergies.”
“Researchers used data on 2,211 persons, age 6 and up, who participated in the National Health and Nutrition Examination Survey 2005 2006 to compare urine levels of dichlorophenols with allergies. Higher levels of exposure were significantly associated with having one or more food allergies.
“Conclusion: High urine levels of dichlorophenols are associated with the presence of sensitization to foods in a US population. Excessive use of dichlorophenols may contribute to the increasing incidence of food allergies in westernized societies.”
- Link to abstract: sciencedirect.com/science/article/pii/S1081120612006710?np=y
6. “Major pesticides are more toxic to human cells.”
“Pesticides are used throughout the world as mixtures called formulations. They contain adjuvants, which are often kept confidential and are called inerts by the manufacturing companies, plus a declared active principle (AP), which is usually tested alone… Despite its relatively benign reputation, Roundup was among the most toxic herbicides and insecticides tested. Most importantly, 8 formulations out of 9 were up to one thousand times more toxic than their active principles. Our results challenge the relevance of the acceptable daily intake for pesticides because this norm is calculated from the toxicity of the active principle alone. Chronic tests on pesticides may not reflect relevant environmental exposures if only one ingredient of these mixtures is tested alone.”
- Link to full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3955666/
7. July 2013: EPA raised allowable limits of glyphosate residues in food.
The new regulation raises glyphosate levels in oilseed crops, which include sesame, flax, and soybean, from 20 parts per million (ppm), to 40 ppm. It also raises the allowable glyphosate contamination level for sweet potatoes and carrots from 0.2 ppm to 3 ppm for sweet potatoes and 5ppm for carrots—that’s 15 and 25 times the previous levels.
While FDA tests foods for pesticide residues, they do NOT test for glyphosate. When asked why, they told Rodale: “Glyphosate requires a specialized method of analysis. FDA is developing a method and hopes to analyze glyphosate in the future.”