So what does organic mean? It means that these pesticides, if used, must be derived from natural sources, not synthetically manufactured. Also, these pesticides must be applied using equipment that has not been used to apply any synthetic materials for the past three years, and the land being planted cannot have been treated with synthetic materials for that period either.
Most organic farmers (and even some conventional farmers, too) employ mechanical and cultural tools to help control pests. These include insect traps, careful crop selection (there are a growing number of disease-resistant varieties), and biological controls (such as predator insects and beneficial microorganisms).
Until recently, nobody bothered to look at natural chemicals (such as organic pesticides), because it was assumed that they posed little risk. But when the studies were done, the results were somewhat shocking: you find that about half of the natural chemicals studied are carcinogenic as well.
This is a case where everyone (consumers, farmers, researchers) made the same, dangerous mistake. We assumed that "natural" chemicals were automatically better and safer than synthetic materials, and we were wrong. It's important that we be more prudent in our acceptance of "natural" as being innocuous and harmless.
Unfortunately, these non-chemical methods do not always provide enough protection, and it's necessary to use chemical pesticides. How do organic pesticides compare with conventional pesticides?
A recent study compared the effectiveness of a rotenone-pyrethrin mixture versus a synthetic pesticide, imidan. Rotenone and pyrethrin are two common organic pesticides; imidan is considered a "soft" synthetic pesticide (i.e., designed to have a brief lifetime after application, and other traits that minimize unwanted effects). It was found that up to 7 applications of the rotenone- pyrethrin mixture were required to obtain the level of protection provided by 2 applications of imidan.
It seems unlikely that 7 applications of rotenone and pyrethrin are really better for the environment than 2 applications of imidan, especially when rotenone is extremely toxic to fish and other aquatic life.
It should be noted, however, that we don't know for certain which system is more harmful. This is because we do not look at organic pesticides the same way that we look at conventional pesticides. We don't know how long these organic pesticides persist in the environment, or the full extent of their effects.
When you look at lists of pesticides allowed in organic agriculture, you find warnings such as, "Use with caution. The toxicological effects of [organic pesticide X] are largely unknown," or "Its persistence in the soil is unknown." Again, researchers haven't bothered to study the effects of organic pesticides because it is assumed that "natural" chemicals are automatically safe.
Pesticide manufacturers have little concern in the matter. To them, "synthetic pesticides sold" and "organic pesticides sold" are both "pesticides sold".
As for conventional farmers, they are not really in a position to be critical. It would not be in their interest to draw attention to chemical and pesticide use.
It is only meant to let you know what you are or aren't getting when you make such a purchase. Unless you know your grower personally, there is no guarantee that your produce has been grown without pesticides or other chemicals. It's a point to consider, given the substantially higher cost of organic foods.
There are many choices and decisions that we, as consumers, are asked to make. Hopefully, this has provided some new information that you will find helpful.
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A formatted MS Word version of this document may be downloaded at:
http://www.ocf.berkeley.edu/~lhom/organics.doc
The data describing the carcinogenicity of natural and synthetic compounds are referenced in Gold, L.S., et al. (1992) _Science_ Vol. 258, pp. 261-265.
Many thanks go to the Organic Crop Improvement Association for their cooperation in this study. The OCIA has chapters in AZ, AR, CA, CO, FL, IL, IN, IA, KS, MD, MI, MN, MO, MT, NE, NM, NC, ND, OH, PA, SD, UT, and WI. Thanks are also extended to the California Certified Organic Farmers, the Ohio Ecological Food and Farm Association, and Oregon Tilth Certified Organic. (The appropriate information has not yet been obtained from the Natural Organic Farmers Association (NOFA), but it is almost certain that all facts stated here apply to their products as well.) The following state Departments of Agriculture have also been very helpful: AL, AK, AZ, CA, CO, DE, FL, HI, IA, LA, MD, MI, MS, MO, ND, OK, SC, TN, VA, and WA. States with no laws governing organic products include Alabama, Delaware, Hawaii, Mississippi, and Tennessee.
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