Combining 2001’s blood lead data

Editor’s note:  This, another internal memo I wrote for the county commissioners, dated November 15, 2001.  Its full title was:  “Combining Panhandle Health District’s and the Spring Health Fair’s blood lead data on children in 2001.”  It was also labeled as “Technical Advisor Note — N3.”


(IMAGE CREDIT:  Google Images)

  1. The Idaho state Board of Health and Welfare (BH&W) recently announced that it opposes the EPA’s expansion of “The Box” and supports instead a program of year-round monitoring of blood-lead levels for the Basin (see SHOSHONE NEWS-PRESS, 11/11/2001, p. A6).
  2. The board’s mention of year-round monitoring may derive from comments taken at a recent Shoshone Natural Resources Coalition luncheon attended by three BH&W members . At said luncheon Mr. Robin Stanley noted that PHD blood samplings were always taken in mid-summer, the dustiest time of the year, probably in order that blood-lead measures be maximized — thus implicitly misrepresenting the Silver Valley’s true blood-lead situation.
  3. In light of the BH&W’s new stress on year-round blood-lead monitoring, it is interesting to assess the impact of combining two recent blood-lead surveys on apparent blood-lead exceedance rates in our area — that is, (a) PHD’s summer survey and (b) a spring survey conducted in a Bealth Fair sponsored by the Mullan and Wallace School Districts in April, 2001.   
  4. The summer 2001 PHD survey collected blood-leads from 117 children aged 6 months to 6 years old. A total of 7 children (or 6%) showed blood-lead levels of 10 ug/dl or higher.
  5. The spring 2001 health fair survey collected blood-leads from 20 children aged 6-years-old and younger. Zero children showed blood­ lead levels of 10 ug/dl or higher.
  6. The combined surveys, therefore, provide a base of 137 children aged 6-years and younger and a total of 7 children (or 5%) at the 10 ug/dl exceedance level or higher. This small decline (from 6% to 5%)  is due to the smaller number of children tested in the spring The combining of the two survey’s nevertheless places the results squarely on the EPA’s ostensible Superfund action standard — namely, 5% of children at or over the  10 ug/dl exceedance level.
  7. In the hypothetical case that the number of blood-lead samples collected in the spring survey were as great as the number collected in the summer survey (and the spring exceedance rate remained the same — i.e., zero), then the combined exceedance rate would have been 7/234 or 3%, now two percentage points (or 40%) below the EPA’s 5% standard.
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