Effect of the mother's consumption of traditional Chinese herbs on estimated infant daily intake of lead from breast milk
Introduction
Traditional Chinese herbs have been used in Chinese society for thousands of years, and consequently many husbands and family members would like to use herbal remedies to keep pregnant women in good health. However, increasing numbers of cases of heavy metal (such as lead (Pb), arsenic (As), and mercury (Hg)) intoxication caused by traditional Chinese herbs have been reported (Chan et al., 1977, Lightfoote et al., 1977, Baker et al., 1985, Huxtable, 1990, Chan et al., 1993, Markowitz et al., 1994). For example, in Taiwan, a 5-month-old baby girl died due to long-term consumption of traditional Chinese herbs, Ba-Pao-NeHwang-San, with a lead level of 44,000 ppm (Chi et al., 1993). There also have been reports of Ayurvedic medications causing lead poisoning in children because of their contamination with lead. Traditional Chinese herbs may be harvested from contaminated soil, so contaminants of herbs can be responsible for unexpected toxicity (But, 1994). These cases have drawn public attention to the regulation and safety of traditional Chinese herbs. However, according to our best knowledge, there are only a few officially recommended upper limits to the levels of heavy metals in traditional Chinese herbs in the world (Uen, 1999).
Lead is neurotoxic and may cause mental deficiency, movement disorders, kidney dysfunction, and abnormal perception, especially during fetal growth and development. Recent studies indicate that lead exposure during the first 3 years of life has the most long-lasting and damaging effects (Pueschel et al., 1996). At this stage, children's developing brains are most vulnerable to lead exposure because children of this age have a less well developed barrier between the blood and the brain, allowing relatively more lead to pass into their developing brains. Also, studies have suggested that lead itself acts to disrupt this barrier (Finkelstein et al., 1998).
Women are chronically exposed to environmental lead since infancy, and they accumulate a significant bone lead burden into the child-bearing age. Maternal body burden and current exposure are major lead sources for the fetus, because lead can pass through the placenta (Ellenhorn, 1997). Breast milk is the first food for infants and it serves as the major nutrient source for biological functions and growth during the early stages of life. There are some data on infant blood lead levels in relation to breast milk lead. Ryu et al. (1985) found a strong correlation between lead concentrations in the breast milk and the corresponding blood lead concentrations of infants until 6 months of age (r=0.42, p<0.0003), before infants begin to crawl and walk. In rats, Bogden et al. (1991) found that lead exposure during pregnancy could retard fetal growth and development, especially if the maternal diet during pregnancy was low in calcium. Gulson et al. (1998) assumed that there was no contribution from environmental samples such as house dust and ambient air. The contribution of lead in the breast milk as the only dietary source to the blood lead level of newborns was estimated from lead isotopic measurements to be in the range of 40–65% (Gulson et al., 1998). Therefore breast-feeding constitutes a major source of exposure to bioaccumulated contaminants for infants.
In Taiwan, little information is available on the association between consumption of traditional Chinese herbs and lead concentrations of breast milk. In this study, we examined the relationship between lead concentrations in breast milk and the consumption of traditional Chinese herbs commonly used during pregnancy and lactation. In order to assess the lead exposure in breastfeeding infants, we calculated and validated a hazard index to evaluate the impact of consumption of traditional Chinese herbs in infants in Taiwan.
Section snippets
Questionnaire collection
A total of 72 healthy mothers were recruited for the study. They were interviewed during pregnancy and lactation to collect information on their sociodemographic characteristics, residential environment, parity, obstetrical history, height and weight before and after pregnancy, occupational exposure history, and consumption of nutritional supplements, traditional Chinese herbs, alcohol, and tobacco. All of the mothers were served by the public water facility. None of the mothers had
Lead concentrations in traditional Chinese herbs
The lead concentrations of four popular traditional Chinese herbs increased in the following order: A. sinensis radix (19.42±0.01 μg/kg)<Z. fructus (33.64±0.31 μg/kg)<L. fructus (36.76±0.01 μg/kg)<Shy-Wuh-Tang (322.31±0.30 μg/kg).
Demographic characteristics and lead concentrations in breast milk
Demographic characteristics of the 72 mothers and the smaller group who were actually followed over time are summarized and in Table 1. Mean body mass indices (BMI) after pregnancy are 25.5±3.81 and 27.0±2.67 kg/m2 for the consumption group and control group,
Discussion
In this study, we calculated HI to evaluate the potential health risk of lead in infants. Our results provided essential information regarding the impact of the mother's consumption of traditional Chinese herbs on lead levels in infants fed breast milk. In addition, we found the highest HI in infants at birth.
Lead concentrations in breast milk in our study are comparable to those found in other studies. In Austria, lead concentrations in breast milk were 36±15 μg/L and have decreased
Acknowledgements
This study was sponsored by the Taipei Medical University (TMC 90-Y05-A102) and the National Science Council, ROC (NSC 92-2320-B-038-043).
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