number of calls that report separate exposure events is unclear; for example, a school­ based exposure may prompt a number of concerned parents to call a poison control center. Media attention regarding a mercury exposure event and state­based mercury initiatives probably influences public awareness and the reporting of mercury events to poison control centers. AOEC PEHSUs. The AOEC maintains the PEHSU network to provide consultation to health care professionals and parents for environmental health concerns affecting chil­ dren and their families (AOEC 2006). Eleven of the 13 PEHSU clinics are located in the United States. PEHSU consultation data dating before 2004 are not easily queried. Therefore, we queried only events recorded for the period from April 2004 through September 2007. The database does not differentiate among calls about elemental, inorganic, and organic mer­ cury. The database includes age, sex, date of call, and PEHSU region. Of the 242 mercury exposure calls, 120 (50%) concerned poten­ tially exposed boys, 93 (38%) concerned girls, and the sex of the remaining 29 (12%) was not identified. The age of the child was recorded for 225 calls; most of these calls concerned children < 7 years of age. The larger percentage of calls concerning younger children may result from the PEHSU focus on young children. Since April 2006, the database also has included the role of the caller (e.g., parent, physician) and the exposure location, identi­ fied as child care, home, public area, school, waste site, or unknown. PEHSUs received 145 calls during the 18­month period from April 2006 through September 2007. In 108 of the 145 calls (74%), the parent of the potentially exposed child made the call. The most common exposure locations identified were homes and child care facilities. These data are limited by passive and incomplete reporting and the general lack of environmental or human exposure moni­ toring data. In addition, how many of these calls may pertain to the same event is unclear. Media attention regarding a mercury exposure event and the implementation of state­based mercury initiatives are likely to influence pub­ lic awareness and the reporting of mercury events to PEHSUs. L i t e r a t u r e r e v i e w . T e n p u b l i s h e d reports met the criteria for inclusion (Azziz­ Baumgartner et al. 2007; Baughman 2006; CDC 2005a, 2005b; Cherry et al. 2002; Gattineni et al. 2007; Gordon 2004; Hryhorczuk et al. 2006; Johnson 2004; Tominack et al. 2002). These 10 publications reported 13 events that exposed approximately 1,393 children between 1998 and 2004. The year of the expo­ sure was not reported for two of these events. The children exposed ranged from 2 to 18 years of age. Exposures took place in homes, cars, schools, and school buses. In eight events, a child obtained mercury by stealing it. Mercury was stolen from a school in 6 of the 13 events (46%), once from a dental office (8%), and once from an industrial site (8%). The mer­ cury was subsequently dispersed or sold to other children. When reported, the estimated amount of mercury spilled/released ranged from 9 to 701 mL. The events reporting the largest releases typically occurred after children stole mercury from an industrial site (~ 701 mL mercury released) or a school (30–40 mL mer­ cury released). When mercury was taken from a school, children typically played with the material at school and then at home, producing exposures in multiple locations. In four additional reports, the exposure resulted from mercury found in the home. The sources of mercury included mercury­ containing devices, prior spills, and mercury stored in the home. The largest potential source for homeb­ased exposure was mercury spills from gas regulators. One publication esti­ mated that mercury was spilled in 1,363 homes (Hryhorczuk et al. 2006). Although many chil­ dren were likely exposed, information is not available to determine how many children were actually exposed in these 1,363 homes. Although the ages of the children exposed ranged from 2 to 18 years, adolescent youths were the most frequent procurers of mer­ cury. Depending upon clinical symptoms and the availability of laboratory tests, many of these children were tested for mercury exposure. The results ranged from < 0.20 to > 1,000 µg/L in urine and from < 4 to 295 µg/L in blood. Neither urine nor blood mercury levels correlate well with the presence or severity of symptoms (Cherry et al. 2002; Gattineni et al. 2007; Tominack et al. 2002). Exposure scenarios. Three location­based exposure scenarios broadly illustrate the nature and public health impact of mercury exposure events. The first two categories are scenarios in the home and at school, two common loca­ tions for childhood mercury exposures. The third category includes exposures at other loca­ tions, such as medical clinics and former indus­ trial properties not adequately remediated. Exposures at home. Although mercury­ containing devices are becoming less common in the home, mercury is still found in some thermometers, barometers, thermostats, electric switches, natural gas regulators, and compact fluorescent lightbulbs (CFLs). Even the small amount of mercury in a typical thermometer (0.5–3.0 g or 0.04–0.22 mL) can be hazard­ ous if spilled indoors and cleaned up improp­ erly (Smart 1986; von Muhlendahl 1990). For example, a 9y­earo­ld boy presented to a hos ­ pital with lethargy, limb pain, and unsteadiness (Rennie et al. 1999). The child’s physical exam­ ination showed mild facial weakness, areflexia, Environmental Health Perspectives • volume 117 | number 6 | June 2009 Children’s exposure to elemental mercury ataxia, and impaired sensation. An investigation revealed that 3 months earlier the boy had dis­ mantled a mercury­ containing sphygmoma­ nometer in his bedroom. Sphygmomanometers contain approximately 11 mL of mercury (Caravati et al. 2008). On discovery of the spill, his parents had attempted to clean up the mer­ cury by vacuuming. After diagnosis, the bed­ room furniture was removed and a mercury vapor–absorbing filter system was used for 3 months to eliminate residual mercury vapor. The boy was treated, and his neurologic symp­ toms slowly resolved over 6 months. Although less frequently reported, other sources of elemental mercury exposure have resulted in home­based exposures. Before 1961, residential natural gas meters and pres­ sure regulators were placed inside the home in parts of the United States. Each gas regula­ tor contained about 10 mL (~ 2 teaspoons) of mercury. As alternative methods became available to reduce gas pressure, the indus­ try began placing regulators outdoors. As a result, gas utility companies started relocating indoor meters and pressure regulators out­ doors. In 2000, a homeowner near Chicago, Illinois, discovered mercury in his basement after his meter and regulator were relocated. This homeowner called the regional poi­ son control center, initiating what eventu­ ally became a multistate response to 500,000 potentially contaminated homes and busi­ nesses (Hryhorczuk et al. 2006). Some folk healers recommend oral inges­ tion of mercury to treat empacho (indigestion). In addition, some practitioners of Caribbean and Latin American religions, such as voodoo, Santería, obeah, Palo, and Espiritismo, use mer­ cury ceremonially (Johnson 1999; Newby et al. 2006; U.S. EPA 2002; Wendroff 2005; Zayas and Ozuah 1996). Mercury may be rubbed onto the skin, added to candles, or sprinkled around the home. These practices potentially expose practitioners and their families. Previous reports document the ceremonial mercury use in neighborhoods whose residents are largely Hispanic (John Snow Inc. 2003; Ozuah et al. 2003; Rogers et al. 2008, 2007; Zayas and Ozuah 1996). Because mercury contamination can persist for years, ceremonial mercury use in the home could also expose future occupants and their children, contributing to health dis­ parities in these populations. Exposures at school. The most common sources of mercury in schools are mercury stored in science laboratories, mercury in broken mercury­containing instruments, and mercury brought to school from other loca­ tions. Additionally, some gymnasium floors contain a mercury catalyst that releases mer­ cury vapor into the air. In 2004, 854 students at a middle school in Nevada were exposed to mercury (Azziz­ Baumgartner et al. 2007; Burgess 2007). 875