RE: ED-Com: Re: [Fwd: CCC Statement] on DBPs

[ttweed@wildrockies.org (Tony Tweedale)]

very imprtant points, which  I missed.  Thanks.  I'm ccing  it to the same
lists.
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>Re questions of health risks of DBPs and THMs I would like to stress that in
>addition to the issue of permissible levels the issues of  timing and
>specificity of sampling locations are important, particularly for
>reproductive endpoints, such as miscarriage, for which the critical period
>may be as short as a few weeks. The current standards require that the
>utility average sampling results over the entire utility (which may be up
>huge and diverse) and then obtaining the average of four quarters (the
>annual average). It is the annual average that must be in compliance, not
>the individual quarterly values. This obviously allows for huge ranges of
>measured values, even if within compliance. In our study in California
>(Waller K, Swan SH, DeLorens G. Spontaneous abortion in relation to exposure
>to trihalomethanes in drinking water. Epidemiology 1998: 9(2):134-140) all
>utilities were within compliance, yet there were quarters in which the
>utility average exceeded 120 for TTHM. The values at particular sampling
>locations could have been still higher. As you probably know, we found a
>fairly strong association with spontaneous abortion (miscarriage) among
>women drinking more than 5 glasses of tap water a day (not an unusually high
>consumption for pregnant women) when TTHM exceeded 80mg/l (and in particular
>when DBCM exceeded 18 mg/l).
>Shanna Swan