Editor’s note: This op-ed — part one of two — was published in the Shoshone News-Press on January 23rd, 2002.
Platonism is a philosophical perspective that regards objects as they appear in the real world as messy and imperfect knock-offs of their ideal and enduring forms. Real dogs for instance come in all sorts of shapes and sizes, but the platonic ideal of “the dog” is perfect and immutable.
More than a little platonism is lodged in EPA’s vision of science - let’s call it “geo-platonism.” Unfortunately, this same geo-platonism makes it difficult to evaluate EPA science the way science is conventionally evaluated — by holding scientific propositions up to empirical testing.
Consider, for example, the IEUBK model that EPA employs in its Human Health Risk Assessment (HHRA) both to estimate basin blood-lead levels and to establish the Superfund’s soil remediation goals.
As I’ve noted previously, the EPA says a blood-lead problem is worthy of community-wide remediation when 5 percent or more of children show blood leads of 10 micrograms per deciliter of blood or higher.
The direct approach to establishing whether or not this standard is exceeded is via a representative survey of childhood blood-lead levels. Surveys are expensive — a basin survey might run $150,000-$200,000 — but even that expense (I’d guess) is significantly cheaper than the indirect, IEUBK-driven method used by EPA.
Using the IEUBK approach demands arduous collection of many measurements of the lead content in environmental media — soils, air, dust, paint, and other sources. These measurements, in turn, are transformed by the IEUBK computer program into an associated probability distribution of blood-lead levels for the children inhabiting that environment.
One might imagine that EPA scientists would be interested in collecting good survey data in order to check their model’s predictions. But EPA’s science policy downplays the importance of survey data — moreover, its policy downplays not only poor survey data but good survey data as well. EPA suggests that the IEUBK’s estimates be favored over available survey data and also authorizes the use of the IEUBK model’s estimates in the absence of any associated survey evidence.
That’s where the EPA’s geo-platonism is in evidence.
In EPA’s view, surveys offer a picture of a world in flux. For instance, childhood behavior patterns vary from season to season, from child to child, and even for the same child at different ages. Even the mere news that EPA is planning to conduct a blood-lead survey might lead parents to temporarily practice better lead-health hygiene, thus leading to falsely low blood-lead frequencies in the survey. A town where good hygiene practices are the norm may one day be replaced by new residents unaware of the environmental risk and thus let that norm slide. In other words the future may harbor lead-health risks that the present has guarded against. For all these reasons (and more) EPA distrusts the evidence it may gather from blood-lead surveys.
Lead content of soil and other environmental media, on the other hand, is by comparison relatively enduring. This leads EPA to prefer gathering data on environmental lead content and then turning to the IEUBK model to estimate expected blood-lead levels from the environmental data.
EPA’s commitment to the primacy of environmental measures over direct blood-lead measures is strong. For example, the SNRC science committee has argued that the Silver Valley has been settled for a long time and therefore current circumstances offer, in effect, a good picture of “the future” — or at least “the future” as it would have unfolded for past generations of locals. We’ve argued as well that the long-term trend in area blood-lead levels is downward rather than upward, and thus the future bodes well for an even better picture. But the EPA is — to date at least — unaffected by these points.
There are some merits in EPA’s focus on enduring environmental realities. Indeed, there is even a kind of benevolence here, however big-brotherish some of us may regard it.
But a deeper problem reside in EPA’s geo-platonist perspective. That perspective can all too easily become a screen protecting bad or unreliable science.
The IEUBK model predicts blood-lead levels — that’s its reason for being. Thus only population blood-lead levels ultimately test whether the model is working well or poorly at a particular site.
The assumption that the IEUBK model has become so perfected and so reliable that it no longer requires survey testing or confirmation must lie behind EPA’s disinclination toward direct testing of the model’s outputs with survey data..
In part two of this article I will lay out why that assumption is not justified .
— Ron Roizen