Project 1:

Controlled Trial in Pregnancy of Dietary Supplements for the Suppression of Bone Resorption and Mobilization of Lead into Plasma

Project leader: Howard Hu
Project co-leader: Mauricio Hernández

Background:

Research has demonstrated that 95% of the lead in the human body is stored in the bones. The lead can be released from the bone under particular circumstances, and one such circumstance is during pregnancy. The release of the lead is known to have a detrimental, toxic effect on the fetus.

Specific aim:

We are undertaking this study to understand how to alleviate the toxic effects of lead in bone. In particular, we are testing to determine if nutritional supplements containing calcium will decrease the amount of lead that is released from the bone during the second and third trimesters of pregnancy and during the postpartum period for women who breast-feed their children. We will measure if the supplements:

• decrease bone loss
• decrease lead that moves from bone to body fluids
• decrease the amount of lead in breast milk

Methods:

This study is designed to determine the effectiveness of using nutritional supplements as a secondary prevention measure against lead exposure for fetuses. To evaluate the effectiveness of these nutritional supplements we have recruited pregnant women with relatively high bone lead levels from family planning clinics in the Mexico City area. These women will participate in a series of evaluations including questionnaires and clinical measures of their blood lead levels, bone lead, food and supplement intake, bone resorption (i.e. bone loss) and turnover, blood lead and breast milk lead. In addition, we will take several body measurements of the mothers and their infants including infant height and weight.

Results:

• This work produced additional evidence of the toxic effect of released maternal bone lead on fetal and infant development.
• Knowing maternal blood lead levels during pregnancy may provide valuable knowledge about the possibility of fetal lead exposure and subsequent health effects.
• All of the levels of lead in breast milk found in this study were below the U.S. EPA standard for lead in drinking water (15 mg/L).
• The lead that is contained in the breast milk is readily absorbed and retained by the infants. Drinking breast milk that contains lead increases the infants’ blood lead levels.

Recent publications:

• Ettinger, A.S., M.M. Tellez-Rojo, C. Amarasiriwardena, T. Gonzalez-Cossio, K.E. Peterson, A. Aro, H. Hu, and M. Hernández-Avila. 2004. Levels of lead in breast milk and their relation to maternal blood and bone lead levels at one-month postpartum. Environ. Health Perspec. 112:926-931.

• Ettinger, A.S., M.M. Tellez-Rojo, C. Amarasiriwardena, T. Gonzalez-Cossio, K.E. Peterson, A. Aro, H. Hu, and M. Hernández-Avila. 2004. Effect of breast milk lead on infant blood lead levels at 1 month of age. Environ. Health Perspec. 112:1381-185.

• Farias, P., M. Echavarria, M. Hernández-Avila, C. Villanueva, C. Amarasiriwardena, L. Hernández, A. Aro, and H. Hu. Bone, blood and semen lead in environmentally exposed Mexican men. Int. J. Environ. Health Res. (in press).

• Guerra-Tamayo, J.L., L. Hernández-Cadena, M.M. Tellez-Rojo, A.S. Mercado-Garcia, M. Solano-Gonzalez, M. Hernández-Avila, and H. Hu. 2003. Time to pregnancy and lead exposure. Salud Publica Mex. 45, Suppl 2:S189-95.

• Juarez-Perez, C.A., G. Aguilar-Madrid, D.R. Smith, M. Lacasana-Navarro, M.M. Tellez-Rojo, G. Piacittelle, H. Hu, and M. Hernández-Avila. 2004. Predictors of plasma lead levels in printing press workers. Am. J. Industr. Med. 46:245-52.

• Tellez-Rojo, M.M., M. Hernández-Avila, D.R. Smith, L. Hernández-Cadena, A. Mercado, E. Palazuelos, A. Aro, J. Schwartz, and H.Hu. 2004. Impact of bone lead on plasma lead levels during pregnancy. Am. J Epidem. 160:668-78

• Wright, R.O., H. Hu, E.K. Silverman, S.W. Tsaih, J. Schwartz, D. Bellinger, S.T. Weiss, Palazuelos, and M. Hernández-Avila. 2003. Apolipoprotein E genotype predicts 24-month infant Bayley Scale score. Pediatric Research 54:819-25.