Based on what, exactly? Japan has one of the highest average lifespans, and the healthiest demographic in this already top-of-the-lifespan-pack nation consume significant amount of white rice, let alone brown.
Many foods can become toxic in excessive quantities. That's why it's best to eat a wide variety of different foods and not get too many calories from any one food. Everything in moderation.
For my friends reading this from Europe, you probably can keep on eating brown rice. In American it’s from pesticide and in Asia from mines erosion to water to rice. Americans might be good with organic one. IMHO the price difference worth the nutritious benefit.
You also can wash your rice to remove 90% of arsenic, basically putting it to wheat and other grains levels.
