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Mauricio Hernandez-Avila,¹ Teresita Gonzalez-Cossio,¹ Eduardo Palazuelos,^2,3 Isabelle Romieu,⁴ Antonio Aro,⁵ Eugenia Fishbein,^1,2 Karen E. Peterson,⁵ and Howard Hu^6,7

¹Centro de Investigaciones en Salud Poblacional, Instituto Nacional de Salud Publica, Cuernavaca, Mexico; ²American British Cowdray Hospital, Mexico City, Mexico; ³Secretaria del Medio Ambiente, Departamente del Distrito Federal, Mexico City, Mexico; ⁴Centro Panamericano de Ecologia Humana y Salud, Organizacion PanAmericana de la Salud, Rancho Guadalupe, Mexico; ⁵Departments of Maternal and Child Health and Nutrition, Harvard School of Public Health, Boston, MA 02115 USA; ⁶Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA; ⁷Occupational Health Program, Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115 USA

Abstract

Despite the recent declines in environmental lead exposure in the United States and Mexico, the potential for delayed toxicity from bone lead stores remains a significant public health concern. Some evidence indicates that mobilization of lead from bone may be markedly enhanced during the increased bone turnover of pregnancy and lactation, resulting in lead exposure to the fetus and the breast-fed infant. We conducted a cross-sectional investigation of the interrelationships between environmental, dietary, and lifestyle histories, blood lead levels, and bone lead levels among 98 recently postpartum women living in Mexico City. Lead levels in the patella (representing trabecular bone) and tibia (representing cortical bone) were measured by K X-ray fluorescence (KXRF) . Multivariate linear regression models showed that significant predictors of higher blood lead included a history of preparing or storing food in lead-glazed ceramic ware, lower milk consumption, and higher levels of lead in patella bone. A 34 g/g increase in patella lead (from the medians of the lowest to the highest quartiles) was associated with an increase in blood lead of 2.4 g/dl. Given the measurement error associated with KXRF and the extrapolation of lead burden from a single bone site, this contribution probably represents an underestimate of the influence of trabecular bone on blood lead. Significant predictors of bone lead in multivariate models included years living in Mexico City, lower consumption of high calcium content foods, and nonuse of calcium supplements for the patella and years living in Mexico City, older age, and lower calcium intake for tibia bone. Low consumption of milk and cheese, as compared to the highest consumption category (every day) , was associated with an increase in tibia bone lead of 9.7 g Pb/g bone mineral. The findings of this cross-sectional study suggest that patella bone is a significant contributor to blood lead during lactation and that consumption of high calcium content foods may protect against the accumulation of lead in bone. Key words: bone lead, calcium intake, environmental factors, Mexico, pregnancy. Environ Health Perspect 104:1076-1082 (1996)

Address correspondence to M. Hernandez-Avila, Instituto Nacional de Salud Publica, Av. Universidad 655, Col. Sta. Ma. Ahuacatitlan, Cuernavaca, Morelos, Mexico.

This work was supported by funding from the NIEHS/Superfund P42-ES05947, NIEHS Center Grant 2 930 ES 00002 USA, The American British Cowdray Hospital, and the Health Ministry, Mexico.

Received 19 January 1996 ; accepted 20 May 1996.