Rarity of lead poisoning raises serious policy questions

‘Public health triumph’ produced very low lead levels

Over there is a giant haystack with a needle somewhere in it. But over here is a small haystack with not only one needle, but a dozen needles in it. Which haystack do you pick to put the effort into finding as many needles as possible? The answer is simple: the small haystack with a dozen needles.

Unfortunately, S.1230, the lead bill sponsored by Senator Pat Jehlen, would have Massachusetts put most of its efforts into searching the giant haystack.

Lead poisoning is a problem characterized by both types of haystack. For the vast, vast majority of children, elevated lead levels occur very rarely, like a few needles in the giant haystack. But in low-income minority neighborhoods that exist in inner-city-type areas of any older city or town, elevated lead levels occur more frequently, like needles in small haystacks scattered in various locations.

S.1230 would have every property in the giant haystack area be inspected – sometimes as often as every two years – for lead paint, although the bill requires nothing to be done about the lead paint once it is found. Lead paint will definitely be found in most housing built before 1978, which is most housing in Massachusetts. Nevertheless, almost no children will be poisoned. Meanwhile, where children will be found poisoned – among the poor – will be ignored.

A very rare ailment

As reported in the Wall Street Journal (December 18, 2007, p. D1), it turns out that lead poisoning is so rare – a few needles in a haystack – that no one wants to fund research into a promising new medication (called d-penicillamine) to lower elevated blood lead levels. Not drug companies. Not charities. Not even lead advocacy groups. Sometimes patients with rare diseases or their relatives pitch in to support research. Not even that has happened with lead poisoning. Only one champion has devised a low cost, high risk way to get a few investors to put up smallish sums of money motivated in part by sheer charity. For its lack of research support, lead poisoning is called an “orphan” ailment.

That’s how rare elevated lead levels are.

It has not always been this way. In 1978, just when lead was banned from gasoline, the median blood lead level in U.S. children was 15 micrograms per deciliter, a level now considered very mildly elevated. By 1999, some 13 years after lead was removed from gasoline, this median lead level had dropped to 2 mcg/dL. This steep drop has been called a “triumph for public health” (New England Journal of Medicine, April 17, 2003, p. 1515).

Harm at low levels?

The question now is whether today’s low lead levels really cause any harm.

To put lead levels in further context, lead poisoning with visible symptoms does not occur until lead levels climb to the “astronomical” vicinity of 170 mcg/dL, and death does not result until over 300 (Technology, 1999, vol 6, p.261). A child used to be considered out of immediate danger on clinical grounds if the level was below 100. For many years before 1970, a level of 60 was considered “elevated” and a “level of concern” by the U.S. Centers for Disease Control (CDC).

From 1970 to 1991, the CDC steadily dropped the level of concern. In 1970, 40 mcg/dL became a new level of concern. In 1978, it dropped to 30, then again in 1984 to 25, then again in 1991 to 10, where it has remained ever since.

At all these lower levels, no symptoms are visible. Doctors and scientists were forced to consider possible hidden impacts: lowering of IQ, attention deficit disorder, speech delays, antisocial behavior, and learning disabilities. The problem with these symptoms is that they only show up when children reach school age (elevated lead levels typically happen around age 2) and are often caused by other factors. In particular, these characteristics are far more common among lower-income minority children compared to other children.

When researchers study the impacts of lead at the very low levels now rarely encountered, their studies face the difficult task of trying to eliminate all those other factors that could cause these symptoms. For example, when an IQ loss of only 2 points or 5 points or 10 points is encountered, is it a result only of a slightly elevated lead level? Or is it caused by any one of many other factors: the mother’s IQ, the mother’s childrearing practices, the lack of reading skills in the home, lack of breast-feeding, and the list goes on and on – ? As a practical matter, researchers cannot control for all these other “confounding” factors, as they are called.

Hence, there is a strong academic dispute over whether or not low levels of lead cause any harm at all. The issue has become politicized. Advocates, including some researchers, are convinced there is harm at any level; others say there is likely no harm at today’s really low “background” levels.

Political options

We do not need to take sides in this scientific debate. Elevated lead levels are rare, and what needs to be done to lower the few remaining elevated lead levels is already known and does not require panic. It does not require lead inspections. It does not require costly abatement where lead is scraped off of wood surfaces in what is a highly hazardous operation itself.

It requires making sure that paint in older homes is kept intact and is not crumbling, chalking or falling off in small particles. It requires using vacuum cleaners and developing cleanliness habits around the home and with children. It requires covering up, planting grass or otherwise barricading soil that may be contaminated.

It requires running the water for a minute in the morning before using it for cooking or drinking. It requires knowing not to sand painted surfaces, especially with power sanders. It requires education, targeted in particular to those poor neighborhoods where elevated lead levels still occur more frequently.

These requirements are more than enough for a very rare ailment that may pose no threat at today’s low levels.

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