pedresel on mon 18 dec 00
IMO there are a number of reasons the allowable limits tend to keep
going down. Ron is correct that in many instances it is because we are
finding out more about problems and risks through doing research on more
substances. But I think there are other reasons which are not based on
science in some instances.
People tend to be willing to make changes to be more cautious, based on
incomplete evidence but unwilling to make changes to be less cautious
because new evidence shows things may not be quite so bad. In some
cases, there are political agendas and what appears to be a bit of
fanatacism.
For example, the US EPA just promulgated regulations for radionuclides
in drinking water. They set limits for many radionuclides based on a
dose of 4 mrem/yr (under an assumed scenario of the amount ingested).
However, they did not follow through on an original proposal on how to
calculate the 4 mrem dose i.e. what concentration would give that dose.
In the past the EPA had been using calculations made in the early
1960s. The proposed standard was to use more current calculations -
based on more recent science and consensus factors agreed on
internationally. Some in the EPA argued that, for carcinogens, no risk
was acceptable so they should never raise standards even if new science
showed the risks were much less than originally believed. They would
lower standards based on new data, however.
So I think that quite often the regulators don't have the courage to
relax standards when warranted and don't really have the interest in
pursuing those situations.
BTW: The uranium standard in drinking water was set at 30 ug/L.
Well I was going to rant about risk/benefit but this is far enough from
clay and long enough anyway. Maybe next time.
-- Evan in W. Richland WA who wishes everyone a Merry Christmas or happy
whatever your seasonal holiday of preference may be.
Ron Roy wrote:
>
>
> If we get into the numbers game - we then also have to start giving amounts
> - and if you have been paying attention the allowable limits keep going
> down - not up. Ever wondered about that?
>
> RR
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