Thursday, February 5, 2009

Contemplating the "Slight" and the "Subtle"

What did you think about Saturday's Washington Post article on the public health implications of the 2001-2004 lead-in-water crisis?

We were perplexed by it.

"Experts View Public Health Impact as Slight," declared the subtitle. The article said:

"The effects [of the harm on children when lead levels in the District's water spiked in 2001-2004] could include the loss of two to three IQ points and a higher risk for behavioral problems, even in children whose bloodstream lead stayed below the threshold of concern set by federal health officials [i.e., 10 micrograms per deciliter]. But at the exposure levels experienced by the District's children, the public health consequences are likely to be very slight, even under the most pessimistic assumptions, according to several experts as well as published studies."

Very slight, even under the most pessimistic assumptions?!

Then the article quoted the Director of the National Center for Environmental Health at the Centers for Disease Control and Prevention (CDC) as saying that at blood lead levels below 10, "the effects are subtle."

"Slight" and "subtle" were the big takeaways.

You do not have to be an expert to suspect that only one part of the story was emphasized here. First of all, "the exposure levels experienced by the District's children" very likely included hundreds, if not thousands of cases, of blood lead levels at or above 10, the CDC's "level of concern." The scientific literature is absolutely clear that blood lead levels far below 10 are associated with loss of IQ and learning difficulties. In the case of DC, the "slight" and "subtle" characterizations reflect precisely the rhetoric of diminishment that has guided official government statements about lead at the tap since 2004.

Let's briefly revisit the Edwards et al. findings:

The study notes that Environmental Protection Agency models of the harm done from DC drinking water in 2003 predicted that hundreds of DC children's blood lead levels would be raised to 10 or above. Moreover, that thousands more would be elevated to lesser levels (5-9, which are now also associated with health harm), because of exposure to lead through drinking water. That estimate was conservative. Indeed, blood lead data collected from Children's National Medical Center showed a much higher incidence of blood lead over 10 in 2001-2003 as compared to previous years, in keeping with the EPA model and prior scientific research on the subject. In 2001, the incidence of elevated blood lead levels for children under 16 months increased by a whopping 9.6 times.

If this many children were affected and, on average, now perform even a little less well in school and have even a little more difficulty focusing on tasks, wouldn't we want readers of the Washington Post to understand the known adverse health effects of childhood lead exposure and the societal costs of such exposure on a citywide scale? From a family's perspective, aren't symptoms like delayed growth, learning impairment, behavioral problems, and difficulty focusing often coupled with extra needs and costs (let alone worry)? Moreover, isn't the public health impact of thousands, if not tens of thousands, of affected children with high (5-9) and elevated (10 or greater) blood lead levels significant?

On Monday, Dana Best, MD, MPH, a nationally recognized expert in pediatric environmental health and co-author of the new study told listeners of WAMU's Kojo Nnamdi show that "we need to stop trying to diminish the effects of lead and what happened. It's happened. We can't undo that. But we can look forward and make sure that we get clean water, clean lead-free housing, and that our schools are the most well run schools that we can give our children. That's the one way that we can actually reduce some of the harm caused by the lead levels..., by providing a very enriching environment. That can help overcome the loss of 3-5 IQ points."

Dr. Best also explained that it is very difficult to ascertain the "most pessimistic" circumstances, mentioned in the Washington Post. "It is very hard to say what is the worst case," she said. "One of the things that is a concern is that these elevated blood leads due to elevated water lead occur in a background of other sources. So if your child is exposed to lead through other sources plus the water lead level then we get something that can be higher than it would have been otherwise. [...] If you have a child who's already at some risk because they had some other problem that caused them to have lower IQ, or some behavioral problems and then on top of that you add lead, you can be ending up with a child who needs special schooling or is unable to develop into a fully functioning independent adult. These are real issues that we are now facing."

The District's now revamped lead poisoning prevention program takes high and elevated blood lead levels very seriously. It sponsors a service that allows any DC family with a child under 6 years of age to request a home visit by trained staff who offer information about lead poisoning prevention and take a few dust samples for lead analysis. If the analysis shows high environmental lead, the program includes a second visit that teaches parents how to properly eliminate the hazard. When a child has blood lead levels of 10 or greater the city sends trained risk assessors to the child's home to identify potential lead exposure sources. The focus of these assessments is on paint, dust, and soil (water is now beginning to be sampled properly as well). When such sources are identified as contaminated, property owners are required to correct them. If they fail to do so, the city has the legal authority to take them to court. And it does.

On average, DC serves about 90 families annually who are identified with blood lead levels 10 or greater for risk assessments and follow-up care. If the number of children harmed from the 2001-2004 lead-in-water crisis is in fact in the thousands, will the city characterize the impact -- in terms of school performance, socially, and economically -- as "slight"? And will all affected families perceive the burden as "subtle"?

Written with input from Ralph Scott, Alliance for Healthy Homes

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