Hmm. Oilseed pollen is heavy, sticky and not wind-blown so is unlikely to be a major cause of hay fever. However, the crop requires inputs of many chemicals ending in -cide, far more likely to cause ill-health. I find the perfume overwhelming and a bit sickening. It's an environmentally-unfriendly crop for other reasons - it is nitrogen-hungry yet occupies the soil for a relatively short time, so leaching or runoff of nitrogenous fertiliser is common. Maize is probably even worse in that regard. You'll never seen oilseed grown organically. The flea beetles it harbours will infest your garden and the oil is third-rate.