[Garden] Rainwater question

[J. Rochon]

Gardeners,
                Have there been any surveys of Waterloo area rainwater 
and its purity? There's an urban myth floating around about a family 
that made itself sick with home-grown veggies. The story is that the 
rainwater in their area was toxic, and they were slowly making 
themselves sick with their produce. While I cannot assert that all 
rainwater, everywhere, is safe at all times, I'd like to be able to 
assure people in the region that this is not a concern for KW resident, 
at least those not beside a factory :-P