Features from Healthcare Journal of New Orleans


What Lies Beneath


Claudia S. Copeland, PHD
PUBLISHED: January/February 2012
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Lead Poisoning in New Orleans

Lead is a dangerous, toxic metal that has contaminated the soil of many New Orleans neighborhoods. Throughout the city, and especially in historic areas, this toxin is commonly detected in the blood of children.

A pervasive public health problem, lead poisoning, though widespread enough to be considered a citywide environmental health epidemic, is often not perceived to be of critical importance, since lowlevel lead exposure is not lethal. However, even very small amounts of lead can be detrimental to cognitive and neurological development in children, leading to the very real possibility that a population of children growing up in neighborhoods with lead-contaminated soil will perform more poorly in school than their peers in clean environments, have lower IQs, and suffer from higher rates of emotional and behavioral problems.

The neurobehavioral effects of lead poisoning are not confined to young children. In elementary-aged children, high lead levels have been associated with disruptive behavior, hyperactivity, distractibility, impulsivity, disorganization, non-persistence, and inability to follow simple instructions. In New Orleans, high lead levels have been associated with lower LEAP scores, according to a 2009 study by S. Zahran and colleagues, a team from Tulane, Xavier, and Colorado State Universities. In fact, this study found that lead exposure was an even more powerful predictor of student performance than class size. In older teenagers, such levels have been associated with an increased risk of dropping out of high school, increased reaction times and slower finger tapping, reading disabilities, lower class standing, increased absenteeism, lower vocabulary and grammatical-reasoning scores, and an increase in juvenile delinquency. It stands to reason that high rates of lead poisoning could lead to higher rates of poverty, disempowerment, and crime in lead-contaminated communities.

While one report found that median soil lead levels had decreased immediately after Hurricane Katrina (presumably due to the inadvertent “remediation” caused by the deposition of relatively less lead-contaminated silt brought in with flood waters), this report did not measure soil lead contamination after the extensive repair work done in the years following the storm. In contrast, a recent report on lead hazards in a representative sample of New Orleans homes, by Tulane public health researchers Felicia Rabito and colleagues, found that over half of all sampled homes had at least one elevated interior sample. Furthermore, almost half of the residences with bare soil had lead levels exceeding the EPA soil lead limit for children’s play areas of 400 ppm, and over a quarter were over 1,200 ppm. (The recommended limits in California, 80 ppm, and some European countries, 40 ppm, are even lower; lead levels in a quarter of the yards were therefore over 30 times the more stringent European standards.) While soil levels varied widely, overall, median lead levels in post-Katrina soil were significantly higher than those of pre-Katrina soil: in a year- 2000 survey, soil lead ranged from 25 to 1,789 ppm; in this recent survey, conducted in 2007-2008, the range was 10-24,000 ppm, representing a median increase of 37%. Higher concentrations were found in and around deteriorating older housing.

While leaded gasoline (outlawed in 1986) has been a major source of lead contamination in many urban settings, it is lead-containing paint (outlawed in 1978, with peak use in the 1920s and a sharp decline in the 1940s) that appears to be the major culprit in post- Katrina soil contamination. Unsafe removal of old, lead-containing paint, especially dry power sanding without the use of properly filtered vacuums, has lead to widespread soil contamination in historic New Orleans neighborhoods, especially those undergoing extensive renovation. Demolition of homes with lead-containing paint is another major source of environmental lead, and has been associated with elevated blood lead levels in children.

The only practical way to remediate lead-contaminated soils is to remove them or cover them with a layer of clean soil. (Fortunately, the same qualities that make lead persistent in the environment— its heaviness and lack of water solubility—also make this method of remediation a practical one.) Prevention of further contamination, of course, is of key importance in lowering soil levels. In September 2001, the New Orleans City Council unanimously passed an ordinance banning dry-sanding of lead-based paint. However, enforcement of this ban has been spotty and disorganized, and the results of the recent survey by Rabito and colleagues indicate that soil levels are in fact rising in many New Orleans neighborhoods.

Though public spaces generally have lower lead levels than private yards, public playgrounds are often adjacent to private homes and therefore subject to the same contamination sources as the surrounding homes. Several playground areas throughout the city have been found to have unacceptable levels of soil lead. Toxicologist Howard Mielke, of the Tulane-Xavier Center for Bioenvironmental Research, and his colleagues found unacceptable soil lead levels in several public playgrounds and daycare center play areas in New Orleans. Community activism in response to data on one of these public playgrounds, Mickey Markey Playground (a.k.a. Little Hands Playground), focused attention on the problem of soil contamination in the Bywater neighborhood, and the play area was remediated by the City in early 2011. Soon after, 13 other playgrounds were tested, and 11 of these were found to have elevated lead levels. All eleven contaminated playgrounds have now been remediated, according to city government data. This represents a small fraction of the 118 parks & playgrounds in the city, but it was a targeted subset of the parks most likely to be contaminated, based on the older nature of the surrounding neighborhoods. Clearly, city officials such as health commissioner Karen DeSalvo have been sympathetic and active in addressing the problem of lead contamination, including by remediating the soil in these contaminated parks, but contamination due to renovation activity continues to be a problem in many neighborhoods.

While reduction of lead in the environment is the most fundamental solution to the problem of lead poisoning, city-wide environmental remediation is, in practical terms, a long-term goal. The more immediate need is to identify children with high lead levels and to take steps to lower these blood levels. This task falls almost entirely to physicians and other healthcare workers who regularly see children in routine health exams. One such physician, pediatrician Theresa Dise, MD, conducts regular blood lead screening on children deemed at risk according to answers to a standard set of questions. She and her colleagues then make decisions about intervention based on blood lead level categories. If the level is less than 10 ug/dl, the family is cautioned but intervention is limited to observation. Blood levels of 10 to 20 ug/dl are judged to confirm exposure, and lifestyle changes such as increased cleaning, hand washing, and removal of shoes at the door are recommended. At levels of 20 to 30 ug/dl, families are recommended to move out of their house, and at levels over 30 ug/dl, chelation therapy may be needed. When elevated blood lead has been found, at any level, testing is repeated until a sustained decrease in the lead level is observed.

Previously, it was thought that blood lead levels under 10 ug/dl in children could be considered “safe.” This is the threshold that New Orleans uses to define lead poisoning, in terms of a definite need for intervention. Unfortunately, however, lead levels above just 5 ug/dl have been associated with lowered IQs, indicating that lead can exert neurotoxic effects even at these low levels. With the soil contamination commonly found in many historic New Orleans neighborhoods, simply playing in their yard or the local playground can easily raise children’s levels to 5 ug/dl or higher. Parents can lower their children’s lead levels through several practical measures: not allowing children to eat or put their fingers in their mouths until they have washed their hands after playing outdoors, mopping floors regularly, and ensuring that children have good nutrition. However, measures like not allowing toddlers to put their fingers in their mouths are easier said than done, and many New Orleans parents have experienced difficulty and frustration in trying to lower their children’s blood lead levels.

Augmenting this difficulty is the fact that many parents remain unaware or peripherally aware of the importance and prevalence of lead poisoning. Dr. Dise has found the awareness of the problem to be “quite variable. Some parents know quite a lot already, some know nothing at all. However, when the lead level comes back high, every parent is very concerned. They may not understand the extent of the possible problem, but they do know lead is bad.” The implications of this variability are twofold: first, increased awareness of the issue is needed, through education and outreach; second, it is vital that at-risk children are routinely tested. Considering the overwhelming prevalence of historic housing here, it may be wise to consider all children in New Orleans to be at risk, and incorporate universal screening of blood lead levels into regular pediatric visits.