3.8 Observers' Comments and Additional Topics on the Prevalence of Soil-Pica Behavior

After addressing the questions on the prevalence of soil-pica behavior, observers had the opportunity to comment on the panelists' discussions. The panelists, in turn, responded to several issues raised by the observers. Following is a summary of these discussions.

• Risk management implications of soil-pica behavior. The observers and panelists debated at length how basing public health evaluations on soil-pica behavior can have great implications on risk management decisions. Three observers addressed this issue before the panelists responded. The first observer argued that the prevalence of pica behavior is too low to form the basis for extensive remedial decisions. Using a Superfund site in Denver as an example, this observer argued that even though several thousand homes have contaminated soils, only a very small subset of these homes have levels of contamination that might be of concern for soil-pica children. Assuming that pica occurs rarely, the observer stressed that soils at very few, if any, homes might actually present health risks. Another observer disagreed, and argued that remedial actions should be taken at sites such as the one in Denver, even if only a small number of children--or even just one child--is at risk. Finally, a third observer stressed that basing risk assessments on soil-pica behavior can lead to excessively expensive remediation projects at sites across the country, including potentially massive remediation activities at the Denver site. This observer wondered if health risks to pica children are sufficient to warrant such extensive remedial actions and whether actions other than soil removal might address these risks.

The panelists also discussed risk management implications of soil-pica behavior and offered different perspectives on the issue. Several panelists recommended that additional studies be performed (see Section 6.0) to reduce uncertainties in the current approaches to evaluating potential health risks to soil-pica children (SD, BL, RW). Some thought these studies should examine the prevalence of soil-pica behavior and the distribution of soil ingestion rates, while others thought they should measure biomarkers and identify adverse health effects. Regardless of the type of study, the panelists thought that more detailed information was needed to give greater confidence in decisions based on risks to soil-pica children. One panelist suggested that ATSDR recommend remediation for properties where levels of soil contamination might pose a risk to soil-pica children, as predicted by the current tools for estimating exposures (NF). This panelist noted that such an approach is already often taken when public health officials identify childhood lead poisoning.

• Public health implications of geophagy versus soil-pica. Reflecting on the observer comments and discussions earlier at the workshop, one panelist highlighted an important difference between geophagy and soil-pica (PS). Specifically, he noted that geophagy is an institutionalized practice in which the processed clays or other geophagical materials do not seem to have any adverse health effects. However, he also stressed that soil-pica can lead to various health effects, whether due to consumption of environmental contaminants or parasites. Accordingly, he recommended that future discussions acknowledge the important difference in the disease-causing potential of these two behaviors.

• Whether soil-pica is "abnormal" behavior. One panelist argued that geophagy is far too common around the world to be considered abnormal behavior (DV). Another panelist noted that incidental ingestion of soils among children--not just those with unusually high intakes--is associated with increased blood lead levels (BL). The same panelist pointed out that soil ingestion at levels of potential health concern is too common to be labeled "abnormal."

• The possibility of geophagy being an inherited trait. One observer asked the panelists if geophagy might be a genetic trait (i.e., mothers can pass the urge to consume clays to their children). In response, one panelist noted that no studies have addressed this issue, but he suspected that cultural influences alone would probably lead to geophagy being most prevalent among families where it is practiced and least prevalent among families where it is not (PS).

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