Pesticides and Produce: What You Need to Know
The Environmental Protection Agency reports that the majority of pesticides now in use are probable or possible cancer causes. Studies of farm workers who work with pesticides suggest a link between pesticide use and brain cancer, Parkinson’s disease, multiple myeloma, leukemia, lymphoma, and cancers of the stomach and prostate.1-3 Collectively, many studies have established strong links between several different classes of pesticides and non-Hodgkin lymphoma among agricultural workers.4 The question remains, however, does the low level of pesticides remaining on our food present much of a risk?
Certainly, it is better to eat fruits and vegetables grown and harvested using pesticides than to not eat them at all, but it is also wise to minimize our pesticide exposure. The Environmental Working Group provides lists of produce called the “Dirty Dozen Plus” (highest in pesticides) and the “Clean 15” (lowest in pesticides). These are their most recent lists.
The large amount of studies performed on the typical pesticide-treated produce have demonstrated that consumption of produce, whether organic or not, is related to lower rates of cancer and increased disease protection. This suggests that the health benefits of eating phytochemical-rich produce greatly outweigh any risk pesticide residues might pose. As such, some scientists argue that the extremely low level of pesticide residue remaining on produce is insignificant and that there are naturally occurring toxins in all natural foods that are more significant. Bruce Ames, Ph.D., director of the Nutrition & Metabolism Center at the University of California-Berkeley, who has spent much of his career to examining this question, believes these minute amounts present pose no risk at all.
He and other scientists in this field support this view because humans and other animals are exposed to small amounts of naturally occurring toxins with every mouthful of organically grown, natural food. The body normally breaks down self-produced metabolic wastes and naturally occurring carcinogens in foods, as well as pesticides, and excretes these harmful substances every minute. Since 99.99 percent of the potential carcinogenic chemicals consumed are naturally present in all food, reducing our exposure to the 0.01 percent that are synthetic will not reduce cancer rates, according to Ames.5,6
These scientists argue that humans ingest thousands of natural chemicals that typically have a greater toxicity and are present at higher doses, compared to the very minute amount of pesticide residue that remains on food. Furthermore, animal studies establishing carcinogenic potential in synthetic chemicals are done at doses a thousand-fold higher than what humans are ingesting in foods. Ames argues a high percentage of all chemicals, natural or not, are potentially toxic in high doses—“the dose makes the poison”—and that there is no evidence of possible cancer hazards from the tiny amounts of chemical residues remaining on produce.5,6
On the other hand, recent studies have documented a link between pesticides ingested from foods and certain diseases. Organophosphate exposure (organophosphate pesticides are used on several crops including corn, apples, pears, grapes, berries, and peaches) during pregnancy or childhood has been associated with low birth weight, ADHD, behavior problems and neurodevelopmental deficits in children.7-10
A number of pesticides may have damaging effects on the brain that contribute to Parkinson’s disease, including paraquat, which is used on a variety of vegetable crops, and organochlorines.11,12 Exposure to organochlorines occurs primarily via fatty foods like meat, dairy, and fish.13 If you are concerned about pesticides and chemicals, keep in mind animal products, such as dairy, fish, and beef, contain the most toxic pesticide residues. Also, glyphosate, which is also linked to non-Hodgkin lymphoma in agricultural workers, is present primarily in processed foods.4,14 By centering your diet on unrefined plant foods you will automatically reduce your exposure to the majority of dangerous chemicals.
Dirty Dozen Plus
Highest in pesticides:
(buy organic, if possible)
Sweet bell peppers
Snap peas (imported)
Kale and collard greens
Lowest in pesticides:
(buy either organic or conventional)
It makes sense to peel fruits, if possible and not to eat potato skins, unless you are able to purchase them organic. Remove and discard the outermost leaves of lettuce and cabbage, if not organically grown, and other surfaces that cannot be peeled can be washed with soap and water, or a commercial vegetable wash.
Environmental and nutritional benefits of buying organic
When we buy organic, we minimize our pesticide exposure, and we are also minimizing the amount of these pesticides that our environment is exposed to. Organic farming is clearly the more environmentally-friendly choice. According to the USDA, organic farming integrates cultural, biological, and mechanical practices that foster cycling of resources, promote ecological balance, and conserve biodiversity.15 Supporting organic agriculture will increase the demand for organic produce and decrease the percentage of farmland (and farm workers) exposed to potentially harmful agricultural chemicals. This will also benefit insects (such as bees) and worms which are essential for the health of our planet as well.
Several studies have suggested that organically grown produce is richer in antioxidant nutrients, than conventional produce. Organic apples, plums, blueberries, grapes, strawberries, and corn have all been shown to have higher antioxidant capacities than their conventional counterparts. Organic strawberries were even found to have more anti-cancer activity than conventional strawberries! Scientists have theorized that when the plants are grown without pesticides, they are forced to deal with the stress of insects, which causes them to produce more antioxidant compounds, which are beneficial to humans.16,17 Buying organic is a wise choice—organic foods taste better, and organic agriculture protects farmers and our environment.
1. Brown TP, Rumsby PC, Capleton AC, et al: Pesticides and Parkinson's disease--is there a link? Environ Health Perspect 2006, 114:156-164.
2. Sanderson WT, Talaska G, Zaebst D, et al: Pesticide prioritization for a brain cancer case-control study. Environ Res 1997, 74:133-144.
3. Zahm SH, Blair A: Cancer among migrant and seasonal farmworkers: an epidemiologic review and research agenda. Am J Ind Med 1993, 24:753-766.
4. Schinasi L, Leon ME: Non-Hodgkin lymphoma and occupational exposure to agricultural pesticide chemical groups and active ingredients: a systematic review and meta-analysis. Int J Environ Res Public Health 2014, 11:4449-4527.
5. Ames BN, Gold LS: Environmental pollution, pesticides, and the prevention of cancer: misconceptions. FASEB J 1997, 11:1041-1052.
6. Ames BN, Profet M, Gold LS: Dietary pesticides (99.99% all natural). Proc Natl Acad Sci U S A 1990, 87:7777-7781.
7. Rauch SA, Braun JM, Barr DB, et al: Associations of prenatal exposure to organophosphate pesticide metabolites with gestational age and birth weight. Environ Health Perspect 2012, 120:1055-1060.
8. Zhang Y, Han S, Liang D, et al: Prenatal exposure to organophosphate pesticides and neurobehavioral development of neonates: a birth cohort study in Shenyang, China. PLoS One 2014, 9:e88491.
9. Bouchard MF, Bellinger DC, Wright RO, et al: Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides. Pediatrics 2010, 125:e1270-e1277.
10. Bouchard MF, Chevrier J, Harley KG, et al: Prenatal exposure to organophosphate pesticides and IQ in 7-year-old children. Environ Health Perspect 2011, 119:1189-1195.
11. Dinis-Oliveira RJ, Remiao F, Carmo H, et al: Paraquat exposure as an etiological factor of Parkinson's disease. Neurotoxicology 2006, 27:1110-1122.
12. Fleming L, Mann JB, Bean J, et al: Parkinson's disease and brain levels of organochlorine pesticides. Ann Neurol 1994, 36:100-103.
13. United States Centers for Disease Control and Prevention. Fourth National Report on Human Exposure to Environmental Chemicals: Organochlorine Pesticides.; 2009.
14. Bohn T, Cuhra M, Traavik T, et al: Compositional differences in soybeans on the market: glyphosate accumulates in Roundup Ready GM soybeans. Food Chem 2014, 153:207-215.
15. United States Department of Agrigulture: National Organic Program. [http://www.ams.usda.gov/AMSv1.0/nop]
16. Grinder-Pedersen L, Rasmussen SE, Bugel S, et al: Effect of diets based on foods from conventional versus organic production on intake and excretion of flavonoids and markers of antioxidative defense in humans. J Agric Food Chem 2003, 51:5671-5676.
17. Olsson ME, Andersson CS, Oredsson S, et al: Antioxidant levels and inhibition of cancer cell proliferation in vitro by extracts from organically and conventionally cultivated strawberries. J Agric Food Chem 2006, 54:1248-1255.