Re: Precautionary principle

[RuthWeiner@AOL.COM]

Clearly this is a case-by-case situation.  What EPA used to do for ambient 

air standards is to set a standard at some sort of level below the lowest 

level at which any effect was observed.  For example, if the cough reflex for 

SO2 is observed at a particular concentration in air, assume that that 

concentration is the maximum of a normal distribution, estimate a standard 

deviation from available data and go 2 standard deviations lower.  

Alternatively, use a lognormal distribution.  That's how we got the ambient 

standards of Sec. 108 of the Clean Air Act.


Another alternative: we have a number of standards in place.  My community 

has been living with the existing arsenic standard for about 30 years, and 

now EPA proposes to lower it significantly, at significant cost.  Is there 

evidence in the community of statistically significant adverse health effects 

from arsenic?  In the past 30 years, what has been the record of doctor 

visits, etc, for arsenic poisoning?  How does this compare with other 

communities that have arsenic in the drinking water?  that don't have arsenic 

in the drinking water?  In this case, if the cost were trivial, the lower 

standard would be accepted, but given the cost, a cost/benefit analysis is 

needed.


Another alternative: look at a natural analogue that has been "lived with" 

for a very long time.  This was the basis for 40 CFR Part 191.


Another alternative: a risk/benefit analysis.  This was done when saccharin 

was put back on the market.  This final point can't be made too strongly.  

Too often we don't look at the adverse effect of using the precautionary 

principle (e.g. people who oppose vaccination because it puts poisons in the 

body, or refusal to have regular dental x-rays).




Ruth Weiner, Ph. D.

ruthweiner@aol.com