Mercury and Breast Milk
[If you view the bibliograhy by following a link to a reference, please use the 'Back' button on your browser to return to the place at which you left-off reading.]
The ability of metal ions to concentrate in mothers' milk has been scientifically established for years, as has the ability for methyl mercury to transfer to breast milk and cause neurologic damage to infants. (69) The investigation of the possible transfer of mercury specifically from amalgam dental fillings to mothers' milk, began in 1990. A study by Vimy et al (236) implanted amalgam fillings, seeded with radioactively labelled mercury, into pregnant ewes. Since radioactively labelled mercury does not occur naturally, it was possible to detect mercury in tissues that were specifically derived from the amalgam dental fillings. The amalgam mercury was found to quickly accumulate in tissues of mothers and foetuses, appearing in foetal tissue within two days of the amalgams being placed in the mother's teeth. In the lactating ewes, the levels of labelled mercury in milk were as much as six times higher than the levels of labelled mercury in their blood.
Another recent study by Vimy, MJ; et al, (237) evaluated mercury related to amalgam dental fillings transferring to breast milk in both animals and humans. In the animal study, lactating ewes with amalgam fillings nursed foster lambs from ewes without amalgam fillings. The amalgam fillings contained a portion of radioactively labelled mercury, which was found in the tissues of the foster lambs. This confirmed the transfer of mercury from the amalgam fillings of the mothers, into the breast milk, then into the tissues of the foster lambs. The human study examined mercury levels in breast milk of 33 lactating women. The mercury levels correlated with the number of amalgam fillings or mercury vapour concentration levels in mouth air. The infant exposure levels were compared to the United States Public Health Service Minimal Risk Level (MRL) standard for adults, and caution was urged. The combination of prenatal mercury exposure and lactating exposure to maternal amalgam mercury was addressed. Other important factors addressed were mercury exposures related to the differences in body mass between infants and adults and the particular sensitivity of infants to heavy metal toxic effects. The findings suggested that placement and removal of "silver" tooth fillings in pregnant and lactating humans will subject the foetus and neonate to unnecessary risk of Hg exposure.
Schumann 1990, Yoshida, M. et al 1994, Oskarsson, A. et al 1995, 1996, (235,245,221) found that any form of mercury can transfer to breast milk and, from there, into the tissues of infants, although the fat soluble forms of mercury (methyl mercury and mercury vapour) will concentrate more in brain tissue of infants. The Schumann study pointed out that milk increases the bioavailability of Hg2+, as the ionic mercury is bound to a greater extent in the red blood cells of the suckling infants. In an evaluation of lactating human females, the study by Oskarsson and Associates found that dental amalgam mercury transferred to mothers' milk, but that methyl mercury from consumption of fish correlated to mercury levels in blood but not to levels in milk. In the portion of the study on rats and mice, the mercury was found to cause pathologic effects in the offspring, including alteration of the thymocytes, increased lymphocyte activities, and effects on noradrenaline and nerve growth factor in the developing brains. These effects occurred in the animals exposed to methyl mercury.
It has been well established scientifically that mercury vapour, being lipid soluble, functions very similar to methyl mercury pathologically. There have been other studies confirming the harmful effects of mercury vapour on unborn babies and developing infants (214,220,238) It should be emphasised that the studies cited herein clearly show that mercury damage to unborn babies and infants is not readily observable early on. The neurological damage is develop- mental in nature, primarily affecting learning, behavior and neurological function. These effects can dramatically alter the functioning of the individual throughout life. Schumann (235) found
that early exposure to inorganic or organic mercury can even result in mental retardation. In a subsequent study, Oskarsson et al (68) confirmed the accumulation of dental amalgam mercury in mothers' milk. This study found that amalgam mercury dental fillings were the main source of mercury in the milk of lactating humans, related the exposure to the World Health Organization standard for daily intake for adults, and concluded it to be significant enough to be a risk to infants.
At this point, the scientific evidence clearly establishes that mercury transfers from amalgam dental fillings to the tissues of unborn babies and to mothers' milk; from the milk to body tissues of infants, and, according to existing standards, presents a health risk to the infants. The combination of prenatal exposure and neonatal exposure from nursing presents an undeniable concern. Oskarsson et al (68) stated: "We concluded that efforts should be made to decrease mercury burden in fertile women."
It is also now documented (50) that mercury in the developing infant and foetus can lead to permanent and irreversible brain damage and is discussed in Appendix 3