Perchlorate quiz perplexes reader

Hi! I have taken the tests in your magazine three times a year since I was first certified back in 1998. Usually there are a few questions on each test that one has to do a little looking (or thinking) outside the story to get the answer. But on the August test (see WQA Recertification Quiz, p. 42), I think one question has no right answer.

Question No. 6 asks what the equivalent to the EPA’s RfD for perchlorate is. The answer certainly isn’t in the story—or at least I don’t see it. A search of the EPA website shows that they “proposed” an RfD in 2002 of 1 ppb. But apparently it isn’t in place yet, and I couldn’t find anywhere that there is an RfD in place that the proposed dose would supercede.

Did I miss something somewhere? I went ahead and checked “A” = 1 ppb based on the proposed RfD since “None of the above” wasn’t an alternative. Thanks for providing this opportunity to get “recert” points!

Mark Kenning
FilterSource
Fort Collins, Colo.

Author’s response: You guessed right for Question No. 6. The intended answer was 1 ppb. I tried to be careful in my wording while writing the quiz. The question should have read “proposed RfD” to be accurate. Sorry for the confusion. Thanks for bringing it to our attention.

Mark V. Rowzee, Education Director
Water Quality Association
Lisle, Ill.

Correction: In September’s On Tap column (“Coliform Bacteria: A Failed Indicator of Water Quality?” page 92), CT was incorrectly referred to as contact time when it should have read concentration multiplied by time.

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