Assuming there’s a lack of toxic effects because a human has not yet named any is fallacious. Safety is inherently impossible to demonstrate with certainty.
In this case, 30 years? Or, taken in another light, it doesn't have effects that are visible on the time-scale of known substances such as lead, arsenic, mercury, etc.
In addition, the parent also stated this:
> I won't be surprised if future studies find longterm effects, such as increasing the risk of cancer, damage to the circulatory system or the brain.