This is for future reference for myself, so I don’t have to hunt down these links again every six months.

Organic pesticides must be cultivated from natural sources, rather than produces synthetically. They are toxic, because that’s the whole point. Where they are less toxic than synthetic compounds, they are used in greater amounts to compensate for that. Most importantly – organic pesticides aren’t studied in depth by the EPA. Synthetic pesticides are. The toxicities and effects of synthetic pesticides are very well known. Organic pesticides have been used for less than ten years, and aren’t well researched. If you are averse to being a “human guinea pig” then you should stay away from organics.

The difference between organic and synthetic pesticides is that organic pesticides must be derived from natural sources, not synthetically manufactured.

When you test synthetic chemicals for their ability to cause cancer, you find that about half of them are carcinogenic.

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.

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 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.

It turns out that a key factor in chemicals being cleared for use on organic crops is whether they occur naturally. Spinosad, for example, comes from the soil bacterium Saccharopolyspora spinosa. It can fatally scramble the nervous systems of insects. It’s also poisonous to mollusks.

“To control fire blight on the same acre of land,” he explains, “I could use a tiny amount of a potent synthetic that has proved safe over the last 50 years, or a much larger amount of an organic pesticide.” He demurs on saying which is better, saying, “I want people to know that there are definitely tradeoffs.”

In the USDA tests, there was ten times as much spinosad on organic lettuce than was found on conventionally cultivated fruits and vegetables.

Copper compounds are used to fight fungal and bacterial diseases in plants. Copper isn’t very toxic to humans, but it can accumulate in the soil and eventually become poisonous to plants and even worms at high concentrations.

The seeming contradiction between organic labeling and potentially harmful pesticide practices may lie in the relative leniency of the USDA organic guidelines

the actual volume usage of pesticides on organic farms is not recorded by the government. Why the government isn’t keeping watch on organic pesticide and fungicide use is a damn good question, especially considering that many organic pesticides that are also used by conventional farmers are used more intensively than synthetic ones due to their lower levels of effectiveness. According to the National Center for Food and Agricultural Policy, the top two organic fungicides, copper and sulfur, were used at a rate of 4 and 34 pounds per acre in 1971 1. In contrast, the synthetic fungicides only required a rate of 1.6 lbs per acre

Rotenone is widely used in the US as an organic pesticide. Because it is natural in origin, occurring in the roots and stems of a small number of subtropical plants, it was considered “safe” as well as “organic”. However, research has shown that rotenone is highly dangerous because it kills by attacking mitochondria, the energy powerhouses of all living cells. Research found that exposure to rotenone caused Parkinson’s Disease-like symptoms in rats, and had the potential to kill many species, including humans.

nearly half of the pesticides that are currently approved for use by organic farmers in Europe failed to pass the European Union’s safety evaluation that is required by law

Canadian scientists pitted ‘reduced-risk’ organic and synthetic pesticides against each other in controlling a problematic pest, the soybean aphid. They found that not only were the synthetic pesticides more effective means of control, the organic pesticides were more ecologically damaging, including causing higher mortality in other, non-target species like the aphid’s predators. Of course, some organic pesticides may fare better than these ones did in similar head-to-head tests, but studies like this one reveal that the assumption that natural is better for the environment could be very dangerous.

This isn’t pesticide related, but – organic foods tend to have higher levels of potential pathogens. One study, for example, found E. coli in produce from almost 10% of organic farms samples, but only 2% of conventional ones10. The same study also found Salmonella only in samples from organic farms, though at a low prevalence rate. The reason for the higher pathogen prevalence is likely due to the use of manure instead of artificial fertilizers, as many pathogens are spread through fecal contamination. Conventional farms often use manure, too, but they use irradiation and a full array of non-organic anti-microbial agents as well, and without those, organic foods run a higher risk of containing something that will make a person sick.