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2.0 Definitions

Central to every charge question was the need to define key terms, such as soil ingestion, soil-pica, and geophagy, and to avoid any ambiguities in the discussions. The panelists noted that their definitions might differ from ATSDR's definitions and from definitions published elsewhere. The panelists cautioned, therefore, that observers and readers should be aware of the definitions for soil-pica and geophagy used in this report and that other individuals or agencies might have different definitions. The panelists considered several factors for their definitions, as described below, but they eventually agreed on the following definitions:

  • Soil ingestion is the consumption of soil. This may result from various behaviors including, but not limited to, mouthing, contacting dirty hands, eating dropped food, and consuming soil directly.

  • Soil-pica is the recurrent ingestion of unusually high amounts of soil (i.e., on the order of 1,000-5,000 mg per day). Groups at risk of soil-pica include children aged 6 years and younger and developmentally delayed individuals.

  • Geophagy is the intentional ingestion of earths and is usually associated with cultural practices.

When defining these terms, the panelists listed numerous factors related to the above terms. Several panelists decided, however, that the aspects of soil ingestion that seem to be most important to ATSDR are (1) the amount of soil ingested, (2) the frequency of ingestion, and (3) the type of material ingested. The panelists' inputs on these and other factors are:

  • Is soil-pica an intentional behavior? One panelist noted that "pica" is often defined as being intentional ingestion of non-food items. Though not disagreeing, other panelists pointed out that the definition of soil-pica should not be limited to intentional soil ingestion, primarily because children can consume large amounts of soil from their typical behaviors and because differentiating intentional and unintentional behavior in young children is difficult. The panelists eventually agreed, and omitted the "intentional" aspect of soil-pica from their definition, suspecting that ATSDR ultimately is most interested in the quantities of soil that children ingest, regardless of whether the behavior is intentional or not.

  • Is soil-pica or geophagy an abnormal behavior? Some panelists thought that soil-pica is often considered abnormal behavior, but the panelists eventually unanimously agreed to omit the word "abnormal" from their definitions because of the word's negative connotations. One panelist was concerned that too many people already believe geophagy to be abnormal, even though the practice occurs world-wide among millions of individuals who are rational and have different education backgrounds. The panelists pointed out that the normal exploratory behavior by a 1- or 2-year-old could involve eating soil while the same behavior in a 4- or 5-year-old might be considered abnormal. Therefore, the panelists chose not to categorize soil-pica as abnormal behavior.

  • Is soil-pica necessarily a recurrent behavior? Some panelists indicated that definitions of soil-pica often imply that the behavior is recurrent, and possibly habitual. (1) After discussing this issue at length, the panelists agreed that the recurrent ingestion of unusually high amounts of soil is an important aspect of soil-pica. They also agreed that children who ingest large quantities of soils only once should not be considered soil-pica children, though they recommended that ATSDR continue to evaluate the health implications of 1-day exposures.

Some observers questioned the panelists' inclusion of "recurrent" in the definition of soil-pica. One observer, for instance, thought the definition should not exclude children who might ingest large quantities of soils on just one occasion. Other observers thought the "recurrent" aspect of soil-pica actually reflected habitual behavior or a "behavioral inclination" to consume soils. The panelists considered these comments, but decided that children who consume large amounts of soil just one time should not be considered soil-pica children. Further, they thought the quantity of soil ingested is the factor that most distinguishes soil-pica behavior, regardless of whether the behavior is habitual, intentional, or inadvertent. Therefore, the panelists did not incorporate the observers' comments into their definition. When asked for a more specific definition of "recurrent," two panelists thought ATSDR should examine the results of soil ingestion surveys in the literature to develop more precise wording for the temporal component of the soil-pica definition.

  • What is the significance of the materials that people consume? When defining geophagy, two panelists stressed that it typically involves consumption of clays from known, and usually uncontaminated sources. The fact that surface soils generally are not the main source of geophagical materials was often highlighted during the workshop. Soil-pica, however, is strictly consumption of surface soils (i.e., usually the top 2-3 inches).

  • Is age a risk factor for soil-pica? When defining soil-pica, the panelists suggested different age ranges for being at greatest risk of exhibiting this behavior. Two panelists noted survey data which indicate that soil ingestion is generally not of concern for infants (aged 0-12 months). Other panelists recommended saying that children 4 years old and under are at risk for soil-pica. Another panelist noted that EPA's children's health initiatives focus on children aged 6 years and younger as being at risk for elevated soil ingestion levels. Another panelist cited analytical studies reporting elevated soil ingestion rates among children up to 7 years old. The panelists decided that "children aged 6 years and younger" should be included in the definition as being at high risk for soil-pica.

After the panelists defined soil-pica, an observer asked if the age group listed in the definition (6 years and younger) was simply chosen to be consistent with EPA's efforts. Suspecting that older children (i.e., 5- and 6-year-olds) have lower soil ingestion rates than younger ones (i.e., aged 4 and younger), this observer wondered if the age range specified in the definition was too broad. Two panelists justified their decision to include 5- and 6-year-olds in this definition. One panelist stressed that children's behaviors that contribute to soil ingestion differ considerably between 1-year-olds and 6-year-olds. However, she noted, behaviors associated with soil ingestion, particularly thumb sucking, tend to decrease markedly after age 6, due to pressures from peers and teachers. Thus, she thought that including children aged 6 years and younger in the definition of soil-pica was appropriate, recognizing that soil ingestion behaviors of children within this age range can vary widely. Another panelist noted that 5- and 6-year-olds may be less likely to engage in mouthing behavior than younger children, but that they are more likely to play outdoors frequently, which might increase their risk for ingesting soils. Therefore, he found it appropriate to indicate that children aged 6 years and younger are at risk for soil-pica.

Eventually, two panelists noted that specifying an exact age range for children at risk for exhibiting pica behavior is somewhat arbitrary and no data adequately support the use of one age range as a cutoff over another. The reviewers summarized the main point of the discussion as follows: the risk of engaging in soil-pica behavior is clearly greatest in young children, as opposed to in infants, older children, adolescents, or adults.

1. The panelists briefly debated whether the definition should have the term "repeated ingestion" or "recurrent ingestion." Noting that "repeated ingestion" might imply a pattern of soil-pica events, rather than these events occurring randomly, the panelists agreed that "recurrent ingestion" is the most appropriate wording for this definition.

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