5

[The mayor of St. Louis, Missouri, Francis] Slay cites the efforts to… and reduce lead poisoning in children as some of his most fulfilling work. Regarding the latter, "The drop has been dramatic," he said. "It was over 20 percent when I took office [in April of 2001], and now it's under three percent of those kids tested [who] have elevated levels of lead in their blood. And more kids are being tested."

— Lauren Brucker, "St. Louis' Mayor", in Saint Louis Brief (the alumni magazine of Saint Louis University School of Law), volume 15, issue 1, [2014,] page 14. (The bracketed phrases "The mayor…" and "in April of 2001" were added by me; the bracketed "who" appears in the article.)

There are a few claims here. Two are:

  1. Mr. Slay is claiming that the number of kids who test positive for lead poisoning has decreased 85% from 20% to 3%. I see no reason to disbelieve him (though confirmation would be nice).
  2. Ms. Brucker is claiming that the mayor's statement is "[r]egarding the latter", that is regarding the decrease in lead poisoning among kids. In other words, she's claiming that there's been a decrease in the percentage of lead-poisoned kids — not just in the percentage of tested-positive-for-lead-poisoning kids. Note that, precisely because "more kids are being tested", there may not have been a decrease at all in the percentage of lead-poisoned kids, even though there was an 85% decrease in the percentage of tested-positive-for-lead-poisoning kids.

I seek confirmation for either of these claims, especially the latter. If I could also get the actual percentage decrease in lead-poisoned kids, that'd be even better.

(I don't know Mr. Slay's definition of "kids" or Ms. Brucker's of "children", so I guess any known percentage decrease for some class reasonably termed "children" will suffice.)

3

There is quantitative data in Childhood Lead Poisoning in The City of St. Louis for every year from 1971 through 2009.

Using a 10 micrograms per deciliter standard, the fraction of children testing positive decreased from 31.1% in 2000 and 16.2% in 2001 to 3.2% in 2009.

By 2014, the fraction testing positive decreased to 1.72% according to Missouri Childhood Lead Poisoning Prevention Program 2014

2

You ask two questions. @DavePhD addressed the first one. The second is also answerable from the same data source. The total number of children tested was 11,260 in 2000 and 13,522 in 2009. This is not enough to explain a decrease in the positive testing rate from 31.1% in 2000 to 3.2% in 2009.

There is a bit of a problem in choosing the bounds though. In 1999, 14,580 children were tested (22.9% positive). That's more than the number of children tested in 2009. Or if we go back to 1995, 20,573 were tested (23.5% positive). So saying that more children are tested may be overstating the matter.

The percentage of children tested has ranged from 39.5% (in 2000) to 47.5% (in 2004) and was 44.8% in 2009. The percent of children tested varies but has been mostly flat. Note that 1999 at 46.6% was the second highest percentage of children tested.

Far fewer children tested positive in 2009 than 2000 in either percentage or absolute terms. The only way that could be misleading would be if it were testing the wrong children. I.e. it is conceivable that they are only testing healthy children and not testing those who would test positive. However, that doesn't accord with the wording of the law, which directs that all high risk children be tested.

From Table 1:

Any child under the age of six years living in or visiting for 10 hours per week or more, the high-risk area, will be tested annually for lead.

Short of testing every child, I don't know that we can answer that more definitively.

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