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.
REFERENCES
1. Council on Scientific
Affairs, American Medical Association. Silicone gel breast implants.
J Am Med Assoc 1993; 270:2602-6.
2. LeVier, R. R., M. C. Harrison,
R. R. Cook and T. H. Lane. What is silicone? Plast Reconstr Surg
1993; 92:163-67.
3. Dunn, K. W., P. N. Hall
and C. T. Khoo. Breast implant materials: sense and safety. Br
J Plast Surg1992; 43:315-21.
4. Bejarano, M. A. and M.
A. Zimmer. Determination of low levels of silicones in human breast
milk by the aqueous silanol functionality test. Midland, MI: Dow Corning
Corporation, 1991. Report No. 1991-10000-36332.
5. Levine, J. J. and N. T.
Ilowite. Sclerodermalike esophageal disease in children breast-fed
by mothers with silicone breast implants. J Am Med Assoc 1994;
271:213-16.
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.
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