Are conventional blueberries bad for me?

Mom sent me an email with questions about blueberries:

I eat blueberries almost every day ... a handful at breakfast....if I eat regular berries constantly will I end up poisoned? Last year I bought some organic..not a lot...the price difference is startling.

I'm so glad my Mom eats blueberries every day, whether they're organic or conventional. The health benefits of eating blueberries far outweigh the possible risk associated with pesticide residues on those berries. According to one estimate, if everybody in the USA ate one more serving of fruits and vegetables daily the number of cancer cases would fall by about 20,000, while only 20 new cases would occur due to increased pesticide consumption. If you can't find organic blueberries, or can't afford them, it would be far better to switch to conventional berries than to eat fewer blueberries.

Blueberries are a wonderful healthy food, low in calories but rich in vitamins, minerals, and fiber. They are also loaded with antioxidants, which help our bodies ward off cancers and heart disease. Organic blueberries have even more antioxidants than conventional blueberries (this is a common finding when organic and conventional fruits and vegetables are compared generally).

Organic blueberries had about 50% more antioxidant activity than
conventional blueberries in tests conducted in New Jersey. Anthocyanins
and polyphenols are both groups of antioxidants that help prevent
cardiovascular disease and cancer. (Data from Sciarappa 2008,
click to enlarge).

People who buy organic food often think of it as pesticide free. That isn't quite true, because some naturally-derived pesticides are allowed for use on organic farms, and some pesticides might move from conventional to organic farms, or persist from the days before a farm became organic. That said, most organic produce carries far less pesticide residue than conventional produce, and eating organic food dramatically reduces dietary exposure to pesticides. This is partly because so many more chemicals are allowed for use on conventional farms than organic.

Pesticides allowed for use use on conventional blueberry farms in British Columbia. Naturally-sourced active ingredients, which some organic certifiers allow for use on organic farms, are marked with an asterisk (*) (BC Blueberry Production Guide, 2015).

Herbicides	Insecticides	Fungicides
1. bentazon	23. acetamiprid	44. azoxystrobin
2. carfentrazone-ethyl	24. Bacillus thuringiensis*	45. Bacillus subtilis*
3. clethodim	25. bifenthrin	46. boscalid
4. clopyralid	26. carbaryl	47. captan
5. dichlobenil	27. chlorantraniliprole	48. chlorothalonil
6. dimethylamine salt	28. cyantranilipole	49. copper oxychloride
7. fluazifop-p-butyl	29. deltamethrin	50. cyprodinil
8. flumioxazin	30. imidacloprid	51. fenbuconazole
9. glufosinate ammonium	31. lime sulfur*	52. fenhexamid
10. glyphosate	32. malathion	53. ferbam
11. halosulfuron	33. methoxyfenozide	54. fixed copper*
12. hexazinone	34. novaluron	55. fluazinam
13. mesotrione	35. phosmet	56. fludioxinil
14. metolachlor	36. pymetrozine	57. fluzinam
15. metribuzin	37. pyrethrin*	58. fosetyl-AI
16. napropamide	38. spinetoram	59. metalaxyl-M
17. oxyfluorfen	39. spinosad*	60. metconazole
18. paraquat	40. spirotetramat	61. potassium salts of phosphoric acid
19. rimsulfuron	41. thiamethoxam	62. propiconazole
20. sethoxydim		63. prothioconazole
21. simazine	Molluscicides	64. pyraclostrobin
22. terbacil	42. ferric phosphate*	65. Reynoutria sachalinensis extract*
	43. metaldehyde	66. triforine

Many of these pesticides are known or suspected carcinogens, hormone disruptors, neurotoxins, developmental toxins, or bee toxins. A 2006 survey by the David Suzuki Foundation (pdf) found that 60 pesticides allowed for use in Canada, including many of those applied to blueberries, are banned outright in other OECD countries. Canadian regulators also tend to set higher pesticide residue limits than those of other OECD nations, allowing for greater consumer exposure to pesticides.

Even so, it would be almost impossible to eat enough blueberries to experience acute toxicity from residues of any single pesticide applied to blueberries. Consider the fungicide boscalid, a possible carcinogen, and the most frequently detected pesticide on samples of blueberries collected in the USA and analyzed by the USDA in 2008. Boscalid was detected on half of the conventional blueberries grown in the USA, and a quarter of imported conventional blueberries, but none of the organic blueberries. According to the EPA, a 20 kg child would have to eat more than twice his weight in boscalid-contaminated conventional blueberries daily before risking acute boscalid toxicity.

Pesticide residue limits are set cautiously for each pesticide and crop. The challenge is that conventional growers rarely use just one pesticide, consumers don't eat just one crop, and each of us reacts differently to the things we eat. That leaves each of us ingesting our own unique and untested cocktail of pesticides, with unknowable results. Current scientific papers examining effects of pesticides on human health note the complexity of assessing risk from pesticide mixtures, leading some to urge an agricultural transition to agro-ecological farming without pesticides.

The people most at risk from pesticides used on blueberries are not those who eat the blueberries, but the farmers and farm-workers who work in the blueberry fields. Canadian farmers face a higher risk of cancers such as Non-Hodgkins Lymphoma than the rest of the population. The more pesticides they use, the greater the risk. Safety protocols help reduce this risk, but the pesticide labels that spell out required protocols can be long and complicated (like labels on prescription medications), so some farmers might not follow them precisely. I once had the disturbing experience of helping a third grade student read pesticide labels so that he could interpret them for his father, who owned a Fraser Valley blueberry farm but did not speak or read English. I have no idea how much of the crucial information was lost in translation.

The vast majority of the pesticides applied to blueberries do not end up on the fruit. Most herbicides, for example, are applied before fruit set, targeting the soil surrounding the blueberry bushes. The pesticides move through the environment with wind and rain. Some end up in groundwater, surface waters, soil, and air. Some decompose rapidly after application; others can persist for years. They may have negative effects on birds, bees, amphibians, beneficial insects, and other non-target organisms. Neonicitonoid insecticides such as imidacloprid, commonly applied to blueberries, have drawn particular attention for their environmental persistence and their negative effects on honeybees and other beneficial insects. They might not harm the person who buys the blueberries directly, but they have an environmental impact.

Organic farming involves much more than eschewing synthetic pesticides. Organic farmers develop whole-farm plans intended to promote biodiversity, resource cycling, and ecological balance. They must use natural sources of nitrogen, which is particularly important in the Fraser Valley, where half of blueberry farms have high or very high levels of residual nitrogen, contributing to groundwater contamination.

The price difference between organic and conventional blueberries is indeed substantial. This week, Rodale's Organic Price Report tool says that organic blueberries cost about twice as much as conventional blueberries at wholesale markets in Boston, Las Angeles and Philadelphia, and three times as much as conventional blueberries in San Francisco. Two years ago, an organic grower on Vancouver Island noted that her blueberries were $4.50 per pound while a major grocery chain was charging just $1.78 per pound.

The problem with blueberry prices may not be that organic blueberries are too expensive, but that conventional blueberries are too cheap, due to over-supply in our region. Farmers in British Columbia have been planting more and more blueberries, expecting growing consumer demand to come with growing awareness of the health benefits of the fruit. Blueberry bushes take 5-7 years to reach full production, so planting decisions made years ago influence the blueberry market today. BC now produces more blueberries than any other Canadian province (or US state), with production increasing annually. Almost all of that production occurs in the Fraser Valley.

By some estimates, BC blueberry growers will harvest about 160 million pounds of blueberries this year, roughly 35 pounds for every man, woman, and child in the province. Canadians have become big blueberry eaters, consuming four-and-a-half pounds per person annually -- more than twice as much as a decade ago, and almost twice as much as a typical American eats today. Even so, British Columbians can hardly put a dent in the local blueberry supply. The vast majority of the crop has to be exported out-of-province if it is to be sold at all. Ontario growers complain that they can't compete with cheap BC blueberries, and accuse BC of dumping blueberries on the market below their cost of production. BC blueberry growers are now seeking buyers in China, India, and Southeast Asia.

In the midst of a blueberry glut, organic blueberries can still be hard to find in BC. The BC Blueberry Council, representing more than 800 blueberry growers, lists just 18 farms that are either "organic" or "spray and chemical free." The Certified Organic Associations of BC lists more than 50 organic farms growing blueberries among some 700 certified organic farms in the province. Many of these organic farms are small, diversified operations, selling directly to consumers. Last week I visited the grocery store near my office in peak blueberry season. They featured lots of locally-grown conventional blueberries, but their organic berries were imported.

The relatively high price of organic blueberries is partly due to strong demand and low supply. Growing organic blueberries is also more expensive for the farmer. No herbicides means more hoes to keep weeds at bay. No synthetic fertilizer means managing and spreading composts or manures. Dedicating land to promote biodiversity and provide habitat for beneficial organisms can mean less land for cash crops. Premium prices for organic products may also enable organic farmers to pay farm workers more.

Locally-grown conventional blueberries are plentiful and healthy, but local organic blueberries are even better... for the consumer, for farm workers, and for the environment.