As far as I understand, the synthetic pesticides may actually be safer since they're designed with human consumption in mind and are able to be synthesized in such a way to limit negative effects on the body. Also, they can be designed to eliminate pests that are harmful to crops while doing little damage to other fauna in a way that organic pesticides can't.
I don't have any sources to cite, just my memory from past reading. If I'm off-base, please let me know!