Dooyema et al. U5MR for the 1-year period (May 2009–May 2010) was 255 per 1,000 live births. Overall, 71% (84 of 118) of compounds reported processing gold ore within their com- pound (Table 2). Compounds participating in ore processing averaged four different pro- cessing activities. Ore drying was performed more frequently in compounds in village A than in village B (69% vs. 49%, p = 0.002). Only 25 compounds reported grinding activi- ties within their compound (Table 2), but 46% (54 of 118) reported grinding activities nearby, and 27% (32 of 118) of compounds reported having ground ore present in their compound. Fifty-six of the 84 (67%) com- pounds processing ore started doing so in the 12 months preceding the investigation (May 2009–May 2010); however, some compounds (33%) reported processing for as long as 18 years. Compounds in village B were more likely to use a well inside their compound than those in village A, who were more likely to use a community well as their main water source (94% vs. 60%, p < 0.001). Blood sampling. Venous blood lead sam- ples were obtained from 59% (204 of 345) of children < 5 years of age. All blood samples indicated lead poisoning (BLL ≥ 10 µg/dL). For 97% (198 of 204) of children, BLLs were ≥ 45 µg/dL, the CDC-recommended thresh- old for initiating chelation therapy (CDC 2002). Eighty-five percent (173 of 204) of blood samples exceeded the maximum detec- tion limit of the LeadCare II instrument (65 µg/dL). Eighty-six blood samples were sent to CDC laboratories for blood lead, mercury, and manganese testing (Table 3). The mean blood lead concentration for children in village A was 153.3 µg/dL (range 55.9–331.0 µg/dL) and 107.5 µg/dL (range 36.5–445.0 µg/dL) for children in village B. The mean total blood mercury level for children in village A was 2.4 µg/L (range 0.3–6.6 µg/L) and 1.4 µg/L Activity Participate in ≥ 1 activities Rock breaking Rock grinding Rock washing Rock drying Rock separating Rock melting Mean number of activities aNumber of compounds. *p < 0.05. Village A (n = 53)a 42 (79) 29 (55) 10 (19) 27 (51) 33 (62)* 22 (42) 22 (42) 3.4 Table 2. Participation in ore processing within family compounds by village [no. (%)]. (range 0.4–6.5 µg/L) in village B. For comparison, the geometric mean value for total blood mercury reported for children 1–5 years of age in the Fourth National Report on Human Exposure to Environmental Chemicals was 0.33 µg/L [95% confidence interval (CI): 0.29, 0.37], with the 95th per- centile measuring 1.8 µg/L (95% CI: 1.3, 2.5) (CDC 2009). Mean blood manganese levels were 14.0 (range 4.0–39.0 µg/L) and 20.9 (range 4.9–40.8 µg/L) in villages A and B, respectively; 66% (57/86) of samples were above the reference range of 7.7–12.1 µg/L for manganese. Environmental sampling. Soil obtained from 116 of 118 compounds was analyzed in the field. Soil lead concentrations ranged from 45 ppm to > 100,000 ppm; 85% of samples exceeded the U.S. EPA threshold of 400 ppm. The average soil lead concentration from household samples analyzed by XRF was 7,959 ppm (range 421 to > 100,000 ppm) in village A and 3,298 ppm (range 45 to > 100,000 ppm) in village B. Four water samples were collected and sent to a com- mercial environmental testing laboratory in the United States for analysis (Bureau Veritas Laboratory, Novi, MI). Community wells in villages A and B had 520 ppb and 1,300 ppb of lead, respectively, exceeding the U.S. EPA action level of 15 ppb lead in drinking water (U.S. EPA 1991). Two convenience water samples, one from a pond and one from a private well in village B, were also tested and had lead concentrations of 250 and 37 ppb lead, respectively. The private well was selected because no ore-processing impact was suspected. The pond was selected because it had been used for sluicing gold ore, and vil- lage livestock were observed using this water source. The lead concentrations of five ore samples from various stages of ore processing measured at USGS laboratories were 331, 9,150, 13,700, 112,000, and 175,000 ppm. Village B (n = 65)a 42 (65) 39 (60) 15 (23) 27 (42) 29 (45)* 30 (46) 32 (49) 4.1 Both villages (n = 118)a 84 (71) 68 (58) 25 (21) 54 (46) 62 (53) 52 (44) 54 (46) 3.8 Table 3. Blood lead, manganese, and mercury concentrations by village. Village Village A Village B n 44 42 Mean 153.3 107.5 Lead (µg/dL) Median Range 143.8 55.9–331 85.7 36.5–445 Manganese (µg/L) Mean 14.0 20.9 Median 11.6 20.1 Range 4.0–39.0 4.9–40.8 Mercury (µg/L) Mean 2.4 1.4 Median 2.1 0.99 Range 0.3–6.6 0.4–6.5 Reference range for lead is < 10 µg/dL and for manganese is 7.7–12.1 µg/L. Health effects of mercury can be seen at > 1 µg/L. 604 ovlume 120 | number 4 | April 2012 • Environmental Health Perspectives This confirmed that some gold ore processed by the villagers was rich in lead content. Bivariate and multivariate analyses. Table 4 summarizes the results of bivariate analyses. Children who died were more likely than children who survived to have had a mother who participated in ore-processing activities [odds ratio (OR) = 1.9; 95% CI: 1.2, 2.9]. Having a mother who participated in grinding, washing, drying, separating, or melting activities was significantly associ- ated with a child’s death (p < 0.05). Children who died were more likely than children who survived to have ground ore present in the compound (OR = 2.0; 95% CI: 1.3, 3.2). Proximity to village grinding activities was not significantly associated with mortality in bivariate analysis. Environmental and demographic vari- ables tested in the logistic regression model are presented in Table 4. Although we col- lected data regarding whether any household member performed ore-processing activities as well as if the child’s mother performed ore- processing activities, the two responses were not mutually exclusive and were highly cor- related in bivariate analysis. Because previous studies have found that a child’s BLL is most related to the mother’s activities and BLL (CDC 2002), we evaluated only risk factors related to the mother’s activities in the logistic regression model. Child mortality was signifi- cantly related to five risk factors in the final model: age of the child, whether the mother performed ore breaking or washing activities, whether a community well was used as a pri- mary water source, and the soil lead level of the child’s compound (Table 5). No potential interaction terms were included in the final model, as they did not improve explanatory power of the model. After controlling for the maternal ore- processing activities of breaking and washing and the environmental factors including water source and soil lead level within the com- pound, we found that children ≤ 24 months of age were 2.7 times as likely to have died as children 25–49 months of age (95% CI: 1.6, 4.4). In addition, children living in a com- pound with a soil lead level of > 1,200 ppm were 3.6 times as likely to have died as chil- dren in a compound with a soil level of < 400 ppm (95% CI: 1.5, 8.5), and children whose primary water source was a community well outside their compound were 3.7 times as likely to have died as children whose pri- mary source was a well inside the compound (95% CI: 2.0, 6.8). Discussion The United Nations High Commission on Refugees (UNHCR) considers a daily U5MR of > 2.0/10,000/day a key indicator that con- ditions in a refugee situation are deteriorating