Lee et al. for a series of 10 words or parts of words that represent terms commonly used to describe children (child, kids, infant, baby, teen, tod­ dler, adolescent, boy, girl, student). Of the mercury incidents reported over the 6­year period, 113 (14%; 113 of 825) were events in which children were potentially exposed. The location of the incident was not reported in 45 (40%) of the 113 events in which children were potentially exposed. When only a street address was given, we used the category “other” to describe the event location. A few events noted more than one exposure location (Table 3). To compare the amounts of mercury released in different events, we expressed the quantity as milliliters of mercury. The amount of mercury released varied from < 1 mL to approximately 1,900 mL. For example, a fire occurred in one event that released approxi­ mately 200 mL of mercury at a school. No information was provided on whether chil­ dren were present during the release. Among the 113 events that poten­ tially exposed children, five people were injured, and five people were hospitalized. Whether the five persons injured were the same five persons who were hospitalized is unclear. The states reporting the most inci­ dents that potentially exposed children were Kentucky, Michigan, Mississippi, and Ohio. In 27 events, persons were evacuated. These evacuations took place in a number of loca­ tions, including homes and schools. National Response Center reports con­ tain the initial conditions of each event and are self­ reported, often by the spiller. Details often are not known or not volunteered in these initial reports, which results in report­ ing errors and missing information. On the other hand, mercury spills that draw media attention and state­based mercury initiatives may result in increased and more thorough reporting. The type of mercury is not systematically recorded, leading to potential misclassification of elemental mercury exposures. Because the National Response Center does not system­ atically collect the age of persons exposed, Table 3. Mercury events reported to the U.S. Coast Guard National Response Center that potentially exposed children, by location, 2002–2007 (n = 113). Category School Home Medical facility or clinic Other locationb Location not reported aExposure locations are not mutually exclusive; there- fore, the number of locations does not total the number of reported events (n = 113). In addition, location is likely biased by the selection criteria of including all expo- sure events at schools or child care facilities. bCategory includes events with street addresses when the specific location (i.e., school or home) could not be determined. 874 No.a 50 5 1 14 45 the information on children was present only when volunteered. Any analysis of these events is limited by these factors. AAPCC National Poison Data System. The National Poison Data System repre­ sents information uploaded in near real time from 61 of 62 U.S. poison control centers. Reporting is passive and voluntary, occur­ ring when a caller reports a known or sus­ pected chemical exposure. Poison control center specialists collect basic demographic data, information about the chemical agent and exposure route, and any reported clinical effects associated with the case. Depending on the nature of the call, a specialist chooses from a preestablished list of chemical agents and selects signs and symptoms from a list of 131 clinical effects. AAPCC classifies persons 19 years of age and younger as children. Between 2002 and 2006, 15,739 mercury­ related calls not associated with broken ther­ mometers were made (Figure 1). Most of these calls concerned elemental mercury expo­ sure events (91%; 14,378 of 15,739). The calls concerning children (n = 6,396) made up 44% (6,396 of 14,378) of the elemen­ tal mercury calls (Figure 1). Although many calls specified dermal exposure or ingestion, such exposures probably also included the potential for inhalational exposure. Michigan and Illinois recorded the most calls to poi­ son control centers for potential childhood mercury exposures. Between 2002 and 2005, 93% or more of the nont­hermometerr­elated mercury exposures in children were coded as an unintentional exposure. In 2006, the per­ centage of unintentional exposures dropped to 80% (758 of 948). The decrease appears to reflect a single event that prompted 157 calls about an intentional exposure. Poison control centers also receive a large number of calls regarding broken mercury thermometers. The types of mercury ther­ mometers recorded include general formula­ tion, basal, high/low, oral fever, baby rectal, yellow back glass, and mercury metal. Calls concerning children made up 68% (30,891 of 45,232) of the mercury thermometer calls. Since 2002, the calls related to mercury thermometer exposures have continued to decrease (Figure 1). AAPCC also records the anticipated health effects of the exposure. Effects are cat­ egorized as minor, moderate, major, not fol­ lowed, and unable to follow (Bronstein et al. 2007). AAPCC describes minor effects as those that have minimally bothersome symp­ toms and generally resolve rapidly. Moderate effects are more pronounced or more systemic in nature. Major effects are those that may be life threatening or result in disability or dis­ figurement. Calls are not followed up when the exposure was judged by the AAPCC to be minimal to nontoxic in nature, the amount of the contaminant released was insignificant, or the route of exposure was unlikely to result in a clinical effect. Between 2002 and 2006, most non­thermometer ­related (93%; 5,966 of 6,396) and thermometer­related (98%; 30,287 of 30,891) calls were reported as not followed up. Five of the 6,396 calls (<1%) regarding children were about events likely to have had a major effect. All five calls were non­thermometer­related. No major effects were reported among mercury thermometer– related calls. A strength of the AAPCC data is that calls are classified as those representing an actual human exposure event or classified as other calls, such as those seeking only information. The limitations of the data relate to the pas­ sive and incomplete nature of the reporting and the general lack of environmental or human exposure monitoring. In addition, the 10,000 8,000 d e c e r s l ive 6,000 laC 4,000 2,000 0 10,108 1,495 2002 8,274 1,494 2003 5,280 1,350 2004 Year 4,333 1,109 2005 Thermometer calls Nonthermometer calls 2,896 948 2006 Figure 1. Number of elemental mercury thermometer-related and non-thermometer-related calls concern- ing children (≤ 19 years of age) made to AAPCC poison control centers, by year: 2002–2006. Thermometer- related calls include general formulation, baby rectal, basal, high/low, oral fever, yellow back glass, and mercury metal thermometers. Non-thermometer-related calls do not include calls regarding amalgams or thermometers. ovlume 117 | number 6 | June 2009 • Environmental Health Perspectives