"A recent draft risk assessment by Health Canada has found that overexposure to boric acid has the potential to cause developmental and reproductive health effects. Since Canadians are already exposed to boric acid naturally through their diets and water, Health Canada is advising that exposure from other sources should be reduced as much as possible, especially for children and pregnant women. The concern is not with any one product, but rather multiple exposures from a variety of sources."
It also specifically warns Canadians, but I'm sure other nationalities may be affected as well ;-)
I doubt the researchers considered that a small sample of the population, myself included, would have concentrations of around 50ppm of Boric acid in their swimming pools. That's likely a reason they don't specifically call out pools.
That said, playing in a body of water with 50ppm of Boric acid may be considered overexposure.