It's not easy to test the effects, because effects are usually long-term, things like cancer can take decades to be noticed, and "organic food" is quite recent. Remember how long it took to be sure smoking tobacco was really toxic. If I look at France (where I live), the "AB" label for organic food was created in 1985, and it's only recently (maybe a decade, even less) that AB food is available in normal supermarkets. So it's hard to have strong data yet on long-term effects. But I hope they'll come in the next decade.
I've been wondering whether there's any solid evidence that organic food is healthier than conventionally produced food-- the arguments I've seen on the subject have been theoretical/aesthetic.
I'm interested in anything in the range from personal stories to scientific studies, but would prefer to avoid extremely general arguments or claims that people who prefer one or the other are demonstrating character defects.
Edited to add: Thanks for the replies. I'm hoping for experiments which test the effects of food produced in various ways on organisms, especially multi-cellular organisms. It was interesting to find out that plants which have to fight off insects for themselves have more mutagens.
The mutation experiment is very cute, but it leaves out the possibility of damage that isn't related to mutation-- for example, hormonal effects. Also, if it's done on a standard bacteria acquiring the ability to make a particular nutrient, this might not be a test for mutation in general.
I realize experiments on organic vs. conventional would be difficult, especially if you're tracking human health. It would be very hard to avoid confounding factors like other lifestyle factors and income.
"Conventional food" is actually a large blob of a concept-- different pesticides, fertilizers, etc. are used on different foods at different times, so finding out what people are actually exposed to would be difficult.