Determinants of bone and blood lead concentrations in the early postpartum period
- Mary Jean Browna,
- Howard Huf,
- Teresa Gonzales-Cossiob,
- Karen E Petersona,c,
- Luz-Helena Saninb,d,
- Maria de Luz Kageyamab,e,
- Eduardo Palazuelose,
- Antonio Aroc,f,
- Lourdes Schnaasb,
- Mauricio Hernandez-Avilab
- aDepartment of Maternal and Child Health, Harvard School of Public Health, Boston, Massachusetts, USA, bCentro de Investigaciones en Salud Poblacional, Instituto Nacional de Salud Pucblica, Cuernavaca, Morelos, Mexico, cDepartment of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA, dUniversidad Autonoma de Chichuahua, Chihuahua, Mexico, eAmerican British Cowdray Hospital, Mexico City, Mexico, fChanning Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School and Occupational Health Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Dr H Hu, Channing Laboratory, 181 Longwood Avenue, Boston, MA 02115, USA
- Accepted 7 April 2000
Abstract
OBJECTIVE This study investigated determinants of bone and blood lead concentrations in 430 lactating Mexican women during the early postpartum period and the contribution of bone lead to blood lead.
METHODS Maternal venous lead was measured at delivery and postpartum, and bone lead concentrations, measured with in vivo K-xray fluorescence, were measured post partum. Data on environmental exposure, demographic characteristics, and maternal factors related to exposure to lead were collected by questionnaire. Linear regression was used to examine the relations between bone and blood lead, demographics, and environmental exposure variables.
RESULTS Mean (SD) blood, tibial, and patellar lead concentrations were 9.5 (4.5) μg/dl, 10.2 (10.1) μg Pb/g bone mineral, and 15.2 (15.1) μg Pb/g bone mineral respectively. These values are considerably higher than values for women in the United States. Older age, the cumulative use of lead glazed pottery, and higher proportion of life spent in Mexico City were powerful predictors of higher bone lead concentrations. Use of lead glazed ceramics to cook food in the past week and increased patellar lead concentrations were significant predictors of increased blood lead. Patellar lead concentrations explained one third of the variance accounted for by the final blood lead model. Women in the 90th percentile for patella lead had an untransformed predicted mean blood lead concentration 3.6 μg/dl higher than those in the 10th percentile.
CONCLUSIONS This study identified the use of lead glazed ceramics as a major source of cumulative exposure to lead, as reflected by bone lead concentrations, as well as current exposure, reflected by blood lead, in Mexico. A higher proportion of life spent in Mexico City, a proxy for exposure to leaded gasoline emissions, was identified as the other major source of cumulative lead exposure. The influence of bone lead on blood lead coupled with the long half life of lead in bone has implications for other populations and suggests that bone stores may pose a threat to women of reproductive age long after exposure has declined.
