I'll help you out: MTBE tastes bad when it gets in the water. Really bad. The WHO performed a study that found it noncarcinogenic in concentrations much higher than those needed to taste it. So if it gets into the groundwater-- and having gasoline leaking into the ground is a pretty bad thing even when MTBE isn't in it-- it needs to be broken down by either bacteria or activated charcoal. When it comes to dangerous chemicals, MTBE doesn't even show up on my radar. You know what we use to replace MTBE? Ethanol. Do you think maybe we can only produce enough grain to meet our ethanol needs through GMO? We're stuck with it.