Breastfeeding remains the best option for
feeding human infants even though environmental contaminants have been
found in human milk. Breastfeeding offers innumerable benefits for
both the baby and the mother. The risks of not breastfeeding are well
documented. Fetal exposure to environmental contaminants appears to be
the biggest problem and breast milk, while a good indicator of fetal
exposure, may help overcome some of the harmful effects.
The article “Rocket-Fuel Chemical
Found in Breast Milk” reported in the Los Angeles Times and other
media this week has caused confusion and alarm among parents and
health care providers.
Perchlorate in human milk:
Response by Jane Heinig, PhD, IBCLC, Paula Benedict, MPH, RD,
and Thomas Hale, PhD, and Jack Newman, MD, FRCPC - February 25, 2005.
Professional
Responses:
Response
from Jane Heinig and Paula Benedict:
Dear Friends,
Recent news accounts indicate that perchlorate contamination in
breast milk of California mothers has reached the point where infant
exposures exceed safe levels. The study cited to support this view
was published on the web on Feb. 23, 2005. (1) It is important that
professionals understand that the study cited includes milk samples
from only 5 women in California and no direct measurements were made
of infant exposure.
While we are all concerned about the presence of perchlorate
contamination in the environment, women wh o breastfeed their
infants should not stop breastfeeding based on this report. This
study does not provide sufficient information about the average
perchlorate content in California mothers’ breast milk, how much is
transferred to the infant, and what, if any, are the adverse effects
of such exposure.
Perchlorate is both a naturally-occurring and manmade chemical found
in the environment. The chemical is used in a variety of
manufacturing processes including the manufacture of rubber, paint
and enamel products, fireworks, highway flares, and rocket fuel.
Human contamination comes from water and food exposures (including
drinking water, cow’s milk and vegetables). Perchlorate
competitively inhibits iodine uptake in the thyroid gland,
potentially reducing thyroid function. (2) Impairment of thyroid
function in expectant mothers may affect the fetus and newborn,
including delayed development and decreased learning capacity. (3)
However, published studies examining the adverse effects of prenatal
exposure to perchlorate in human populations have produced mixed
results. (4-7) No studies have been published describing measured
infant intakes of perchlorate (through breast milk) or prevalence of
adverse effects of exposure among breastfed infants.
The study cited by the press has several important limitations:
· While the researchers state that the participating mothers were
randomly selected, no description of their population sampling
method is provided.
· A total of 36 mothers from 18 states participated in the study and
5 were from California. Such a small sample size, however it was
obtained, is not sufficient to be representative of the general
population.
· There is no description of the methods used for milk sampling.
Timing since the last feed a nd the completeness of milk expression
strongly influence values in chemical tests of human milk.
Perchlorate levels are particularly likely to be associated with
recent exposure. An expert panel has provided guidelines for milk
sampling for chemical testing. (8) There is no evidence that these
guidelines were followed.
· The researchers did not directly measure infant perchlorate
exposure. Hypothetical exposures were estimated from calculations
using assumed milk volume and a transfer rate of the chemical
predicted by experiments in rats. No information is provided about
the age of the infants in the study or their consumption of other
foods and fluids. Therefore, actual infant exposures are likely to
vary widely from the estimated values.
· The researchers suggest that iodide levels in the milk samples
were inversely associated with perchlorate concentration (at the
highest levels of contaminat ion) but the sample size was so small
that they were not able to examine this association statistically.
Since the action of perchlorate is to bind iodide, women may wish to
discuss their exposure risk with their physicians and consider
increasing their iodide intake through switching to iodized salt or
consuming a supplement. This study does not provide any evidence
that California women should not breastfeed their infants.
Jane Heinig, PhD, IBCLC and Paula Benedict, MPH, RD
References:
(1) Kirk AB, et al. Perchlorate and iodide in dairy and breast milk.
Environ Sci Tech, pre-publication on web.
(2) Greer MA, Goodman G, Pleus RC, Greer SE. Health effects
assessment for environmental perchlorate contamination: the dose
response for inhibition of thyroidal radioiodine uptake in humans.
Environ Health Perspect. 2002;110:927-37.
(3) Technical Briefs: Perchlorate: Questions and Answers. J of Envir
Health Nov 2004; 67, 4.
(4) Kelsh MA, et al. Primary congenital hypothyroidism, newborn
thyroid function, and environmental perchlorate exposure among
residents of a Southern California community. J Occup Environ Med.
2003;45:1116-27.
(5) Brechner RJ, et al. Ammonium perchlorate contamination of
Colorado River drinking water is associated with abnormal thyroid
function in newborns in Arizona. J Occup Environ Med.
2000;42:777-82.
(6) Crump C, et al. Does perchlorate in drinking water affect
thyroid function in newborns or school-age children? J Occup Environ
Med. 2000;42:603-12.
(7) Li Z, et al. Neonatal thyroxine level and perchlorate in
drinking water. J Occup Environ Med. 2000;42:200-5.
(8) Berlin CM Jr, et al. Conclusions, research needs, and
recommendations of the expert panel: technical workshop on human
milk surveillance and research for environmental chemicals in the
United States. J Toxicol Environ Health A. 2002 Nov
22;65(22):1929-35.
Response from Tom Hale:
http://neonatal.ama.ttuhsc.edu/lact/html/perchlorate.html
I have reviewed this article on Perchlorate in cow and human milk.
While I have some problems with their methods of collecting milk
(both cow and human), the data is still somewhat preliminary, they
simply have too few samples to really make much of a case. They also
tried to make the case that the higher the perchlorate, the less
iodide in milk. While this seems logical, in two of their human
samples (TX76, TX78), the highest milk iodide levels reported were
in mothers at supposedly high perchlorate levels (11.3 and 12.7 ug/L).
Seems kind of odd! In several other cases(4) the higher the
perchlorate level the less the iodine...but this was only 6 cases
out of 36 mothers.
The most important factor for mothers to understand, is that with
high perchlorate levels, the amount of iodine in their milk MAY be
lower, we're not really sure at this point. But has the incidence of
hypoth yroidism in breastfed infant increased lately? Not that I
know of. I just spoke with one of our Pediatric endocrinologists and
they are not seeing any change in the incidence of hypothyroidism as
of yet.
These authors also suggest that mothers might want to supplement
themselves with higher iodine levels. Because iodine is actually
pumped into human milk, sometimes at high levels, I worry that the
random supplementation of mothers with iodine may actually overdose
some infants and cause more problems than we had to begin with. This
is because the overdose with iodine is sometimes much worse than the
underdose.
So at this time all mothers should continue to breastfeed and not
worry about the perchlorate issue. Have their pediatricians evaluate
their infants at the routine visits for hypothyroidism (which every
pediatrician does anyway), and not to worry about this contaminate.
In Summary:
1)--Perchlorate inhibits the uptake of iodine by the thyroid gland,
and its secretion into hum an milk.
2)--The only known complication is hypothyroidism, which is easily
treated with supplements of iodine, or in rare cases thyroxine.
3)--Be extremely cautious of supplementing yourself with extra
iodine, you may actually do more harm to your infant by overdosing
with iodine, than by underdosing with "perchlorate".
Lastly, this is the third time in the last several years that
environmental contaminates have been found at low levels in
breastmilk. This and a lot of other data is suggesting that we
humans simply must become more proactive at voting for candidates
that support environmental standards because our whole future
depends on it.
Tom Hale Ph.D
Professor of Pediatrics
Texas Tech University School of Medicine
Response from Jack
Newman, MD, FRCPC
Once again the
media are having a heyday with breastmilk and showing how toxic it
is. And once again, women will stop breastfeeding or not start
because of this, to their own and to their babies' detriment.
What are the issues exactly? First of all, there are undoubtedly
toxins in breastmilk. But why do we imagine that somehow formulas
are free of toxins? What sort of blindness makes us forget that
toxins are everywhere and that the substitutes for breastmilk are
not as pure as the driven snow. Oh, yes, I forgot, the driven snow
is not so pure any more either.
But there is more. Toxins may interfere with the baby's cognitive
and neurological development. Yet, breastfed babies do better on
cognitive and neurological testing than artificially fed (formula
fed) babies in virtually every study that was ever done. Toxins may
interfere with the baby's immunity. Yet, breastfed babies have a
better and more mature immunity than artificially fed babies, and
are less likely to develop infectious diseases. Toxins may increase
the risk of cancer. Yet, breastfed babies have a lower incidence of
certain cancers later in life than artificially fed babies. And this
particular toxin, perchlorate, is associated with more health
problems. Yet breastfed babies, in many studies have fewer visits to
the doctor and fewer hospitalizations.
Jack Newman, MD, FRCPC
Professional
Responses:
