Silicone Breast Implants and Breastfeeding
Cheston M. Berlin, Jr. MD
Hershey Medical Center, Hershey, PA
from Breastfeeding Abstracts,
February 1996, Volume 15, Number 3, pp. 17-18.
Over the past three decades, approximately 850,000 women have received silicone breast implants for cosmetic or reconstructive purposes. Recently, concerns have come to light about illnesses in some of these women, especially connective tissue disease (sometimes referred to as human adjuvant disease), and in April 1992, the United States Food and Drug Administration declared silicone implants would be available only through controlled clinical trials.1 Questions have also been raised about the health of the offspring of these women, especially those infants who have been breastfed. However, there are no data on the incidence or length of breastfeeding in these women.
Breast implants made of silicone materials generate two issues of concern relative to breastfeeding. First, do the implants leak silicone compounds into human milk? Silicone is widely present in the environment and avoiding ingestion is difficult. Silicone drops have been used for years in both the U. S. and Europe for colic. Second, do the implants cause some type of immunologic disease in the infant? This could be caused either by prenatal transfer or by excretion into the milk of an antibody-antigen complex which then may be absorbed through the infant's gastrointestinal tract and distributed to target tissues where a pathologic response may be triggered.
Silicon (Si) is the second most common element in the earth's crust; oxygen (O), the most common. Together these two elements comprise 75 percent of the earth's crust. In its natural state, one silicon atom is surrounded by four oxygen atoms forming an orderly three-dimensional network. Silica is the term for both the simplest SiO2 compound and for its various three-dimensional structures. Silica is inert and permitted as a food additive. The only well-documented human health hazard from silica is a result of inhaling crystalline silica dust into the lungs, causing silicosis (pulmonary fibrosis). This type of silica is never used in breast implants. When silica lacks its highly ordered geometrical structure, it is termed "amorphous silica" and is thought to lack the ability to cause fibrotic reactions. Other important silicon compounds include silicic acid (where a hydroxyl [OH] group replaces one or more of the oxygen atoms) and organosilicates (where organic groups such as methyl, ethyl or vinyl are attached to the silicon atom). Any compound which contains an Si-O bond is termed a silicone.2
The compound produced for most biologic implants is polydimethylsiloxane [PDMS], a silicone polymer which is insoluble in biological fluids with an average molecular weight of 24,000.3 Straight chains of PDMS are fluids; cross-linked chains of PDMS are gels or solids, depending on the type and extent of cross-linking. A silicone elastomer can be produced by adding amorphous silica to highly cross-linked PDMS. This is then used as a barrier to surround the PDMS gel to produce silicone gel implants. The internal PDMS gel may bleed through the elastomer envelope and then, engulfed by phagocytes, may be transported anywhere in the body. Large amounts may produce granulomas.
Because of the widespread presence of silicon compounds in the environment, measurement of elemental Si in biological systems is difficult. However, an assay of silicone in human milk was conducted by Dow Corning on six samples of milk from lactating women with breast implants. This laborious assay requires 10 days to complete and measures PDMS, not elemental Si. The amount of PDMS in the milk of women with implants was not statistically different from that in water blanks or control human milk samples. The milk from women with polydimethylsiloxane [PDMS] implants, 3.62 ppm; control milk, 3.40 ppm; water, 2.25 ppm.4 Another study with more subjects and broader measurements is underway at Baylor University College of Medicine.
At least two recent reports have focused on clinical descriptions of children whose mothers have had breast implants. In one report, the children, non-randomly selected, exhibited some physical symptoms which included abnormal results from motility studies of the esophagus, recurrent abdominal pain and other gastrointestinal symptoms, and decreased weight-height ratios.5 However, these children were selected by referral by physicians and support groups responding to parental concern over possible health effects in the infant whose mother had implants. Many factors in this report were not well controlled and bear closer examination before conclusions are drawn on the relationship between the symptoms reported in the children and their mothers' implants. The second report describes two children with rheumatic complaints who were breastfed by women with breast implants. To date, neither child has been diagnosed as having any connective tissue disorder.6
These cases reflect an extremely small sample in comparison to the large number of women who have had implants. Studies of a larger number of women and their offspring are critical to any conclusions. We also need to know much more about the biology of silicone, its absorption pattern from the gastrointestinal tract, possible metabolic conversion in the liver and other tissues, renal excretion, and binding to tissue protein or bone. Further study, especially involving genetic studies such as HLA typing, may reveal certain families at risk for both maternal connective tissue disease and similar illnesses in the children. Women with clinical illnesses suggestive of human adjuvant disease may represent a subset whose infants may be at a greater risk. Until such data are acquired, or a more definite clinical syndrome identified, there should be no absolute contraindication to breastfeeding by women with silicone breast implants.7
Substantial portions of the article were reprinted with permission of Pediatrics.
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6. Teuber, S.S. and M. E. Gershwin. Autoantibodies and clinical rheumatic complaints in two children of women with silicone gel breast implants. Int Arch Allergy Immunol 1994; 103:105-8.
7. Berlin, C. M. Silicone breast implants and breast-feeding. Pediatrics 1994; 94:546-49.