PCBS LINKED TO LOW IQ In Children
*********************************************************************
. ========== .
. Environmental Research Foundation .
. P.O. Box 5036, Annapolis, MD 21403 .
. Fax (410) 263-8944; Internet: erf@rachel.clark.net .
. ========== .
. Back issues available by E-mail; to get instructions, send .
. E-mail to INFO@rachel.clark.net with the single word HELP .
. in the message; back issues also available via ftp from .
. ftp.std.com/periodicals/rachel and from gopher.std.com. .
. Permission to repost, reprint or quote is hereby granted. .
. Subscribe: send E-mail to rachel-weekly-request@world.std.com .
. with the single word SUBSCRIBE in the message. It's free. .
=================================================================
PCB EXPOSURE LINKED TO LOW IQS
A study published last week confirms that children exposed to low
levels of PCBs in the womb grow up with low IQs, poor reading
comprehension, difficulty paying attention, and memory
problems.[1] PCBs are a family of toxic industrial chemicals
commercialized in 1929 by Monsanto, and now found in all humans
on earth. (See REHW #327.) This latest study, published in the
NEW ENGLAND JOURNAL OF MEDICINE, describes a group of children
--now 11 years old --whose mothers ate PCB-contaminated fish from
Lake Michigan more than once a week for several years before
giving birth. The children's mental, physical, and emotional
growth has been followed since birth. The mental deficits are
most obvious in the 11% of the children with the most PCBs in
their blood.[2]
Starting 15 years ago, Joseph and Sandra Jacobson,
husband-and-wife psychologists at Wayne State University in
Detroit, Michigan, looked at babies born to women who had eaten
trout and salmon from Lake Michigan. Fish from polluted lakes,
rivers, and coastal waters are a well-established source of PCBs
and other contaminants. The Jacobsons asked several thousand new
mothers about their fish-eating habits and studied the children
of more than 200 of them.
The Jacobsons analyzed the PCB levels found in the blood of each
baby's umbilical cord, as an indicator of PCB exposure before
birth. At birth, they found, children who had higher exposures
to PCBs had smaller heads and lower weights. At seven months,
they tested the babies for mental function by showing them two
identical photos for about 20 seconds. One of the photos was
then paired with a new photo and shown to the baby again. The
normal response for an infant is to spend more time looking at
the new picture, indicating that it recognizes the familiar one.
The babies who had the highest exposure to PCBs, however, spent
as much time looking at the old photo as the new one, suggesting
either deficits in short-term memory or attention problems.
When the children were four years old, they were given a battery
of mental tests.[3] Again the highly exposed children showed
memory impairments, this time in tests that asked them to recall
progressively longer strings of words and numbers. The
differences in scores between unexposed and the highest-exposed
children, says Joseph Jacobson, "would be like ten points on an
IQ test. We're not seeing mental retardation, but we are seeing
that the children are just not doing as well."[4]
The latest study, published last week, shows that these mental
deficits last at least until age 11.
These children were not living next to a toxic waste dump, and
their mothers had not eaten PCB-laden fish every day during
pregnancy. Their exposure to PCBs, while on the high side, is
still considered to be within the range of normal background
exposure levels, says Jacobson. Other possible causes, such as
lead exposure or the mother's intake of tobacco or alcohol, were
ruled out. (Unfortunately, maternal exposure to methyl mercury
was not assessed by the Jacobsons, weakening their study.[5])
Two other studies of children have found similar problems from
PCB exposures. In the Netherlands, researchers found that
18-month-old children born to women who carried relatively high
but still "normal" levels of PCBs were more likely to be
neurologically "nonoptimal." In fact, the higher their exposure
to PCBs, the lower their neurological scores. In that study the
mothers had eaten normal diets; they got their contaminants
through their food and probably from water and air.[6]
In the United States, researchers at the State University of New
York (SUNY) at Oswego have found that babies born to "high fish
eaters"--women who in their lifetimes had eaten at least 40
pounds of fish from Lake Ontario--tested worse on several scales
than did babies born to "low fish eaters" and "non-fish
eaters."[7] Fish in Lake Ontario are highly contaminated with
PCBs, dioxin, hexachlorobenzene, DDT and its breakdown product
DDE, mirex, and other chemicals.
"We looked at the kind of stuff a pediatrician assesses in a
newborn," explains Edward Lonky, a developmental psychologist at
SUNY Oswego. "One of our main findings was in regard to
habituation, which is a measure of neurological intactness. It's
one of the tests we use to assess fetal alcohol babies, crack
cocaine babies, and babies exposed to environmental contaminants.
You shine a light through the eyelids of a lightly sleeping
newborn and you get a startle response. When the body settles
down, you repeat the light. The startle response should
habituate, or diminish, over repeated administrations."[4]
Normally an infant will show better habituation on the second day
of testing. Lonky and his colleagues found that infants from the
high-fish-eater group showed poor habituation responses as well
as a greater number of abnormal reflexes and stress responses.
Such effects may not be rare. "These were not people who were
eating fish every day," stresses Linda Birnbaum of the EPA (U.S.
Environmental Protection Agency). "I believe the data suggest
there are subtle changes going on in at least a portion of our
population."[4]
The Jacobsons' latest findings have been mirrored in several
animal studies,[8] and in studies of Taiwanese children
accidentally exposed to high levels of PCBs.[9]
Joseph Jacobson told the NEW YORK TIMES that brain damage caused
by low-level exposures to PCBs was comparable to the damage found
in children exposed to low levels of lead.[10] The difference is
that lead has only afflicted industrial societies; PCBs have
contaminated and damaged human populations of all kinds,
including the Inuit people in the Arctic and other native groups
who eat fish and fish-eating mammals like seals. (And, of
course, the damage from PCBs is added on top of whatever brain
damage has been done by lead, mercury, pesticides, and other
chlorinated hydrocarbons.[11])
It has been known for some years that children are more
susceptible to damage from PCBs, and other toxics, than adults
are. Some of the reasons:
** children absorb chemicals better than adults, through their
skin, their gastrointestinal tract, and their lungs;
** children --especially prior to, or shortly after, birth --have
poorly-developed systems for detoxifying chemicals;
** infants get much of their nutrition from one source, mother's
milk, which is rich in fat, and many toxins, such as PCBs are fat
soluble. (Nevertheless, breast feeding remains far more
beneficial to the child than any alternative.)
** children take in more calories per pound of body weight,
compared to adults;
** children have more skin contact with the outside and household
environments, compared to adults, and exhibit hand-to-mouth
exploratory behavior.
These factors can add up to much greater exposures for children.
For example, a nursing infant typically takes in 10 times as much
dioxin each day as an adult does. When this is calculated on the
basis of "dioxin taken in per pound of body weight," the infant
takes in 100 times as much dioxin as an adult.[12]
Between 1929 and 1989, total world production of PCBs (excluding
the Soviet Union) was 3.4 billion pounds, or about 57 million
pounds per year. Even after the U.S. banned PCBs in 1976, world
production continued at 36 million pounds per year from 1980-1984
and 22 million pounds per year, 1984-1989. The end of PCB
production is still not in sight.[13]
The whereabouts of 30 percent of all PCBs (roughly a billion
pounds) remains unknown. Another 30 percent reside in landfills,
in storage, or in the sediments of lakes, rivers, and estuaries.
Some 30 percent to 70 percent remain in use. The characteristics
of PCBs (their stability and their solubility in fat) tend to
move them into the oceans as time passes. Nevertheless, it is
estimated that only one percent of all PCBs have, so far, reached
the oceans.[13]
Without major efforts to locate, capture, and destroy the
one-to-two billion pounds of PCBs that are "out there," future
generations will continue to be poisoned by PCBs, at great social
(and individual) cost. We hear much of late about the good
intentions of the Monsanto Corporation. Some of our friends tell
us this corporation has turned over a new leaf, and is committed
to behaving responsibly. If this is so, Monsanto could
demonstrate its awakening by leading an effort to locate and
destroy PCBs. Monsanto created (or licensed the creation of) all
the PCBs in the world. This corporation could demonstrate its
commitment to environmental sustainability by cleansing the
planet of this brain-damaging substance, to the extent possible.
An obvious first step would be to undertake a comprehensive
inventory of the problem, assessing the damage done so far and
cleanup-costs, as a demonstration of good faith and serious
intentions.
--Peter Montague
(National Writers Union, UAW Local 1981/AFL-CIO)
[1] Joseph L. Jacobson and Sandra W. Jacobson, "Intellectual
Impairment in Children Exposed to Polychlorinated Biphenyls in
Utero," NEW ENGLAND JOURNAL OF MEDICINE Vol. 335 No. 11
(September 12, 1996), pgs. 783-789.
[2] Joseph L. Jacobson and Sandra W. Jacobson, "Dose-Response in
Perinatal Exposure to Polychlorinated Biphenyls (PCBs): The
Michigan and North Carolina Cohort Studies," TOXICOLOGY AND
INDUSTRIAL HEALTH Vol. 12, Nos. 3/4 (1996), pgs. 435-445.
[3] Joseph L. Jacobson and others, "Effects of in utero exposure
to polychlorinated biphenyls and related contaminants on
cognitive functioning in young children," JOURNAL OF PEDIATRICS
Vol. 116 (January, 1990), pgs. 38-45. And see: Joseph L.
Jacobson and others, "Effects of Exposure to PCBs and Related
Compounds on Growth and Activity in Children," NEUROTOXICOLOGY
AND TERATOLOGY Vol. 12 (1990), pgs. 319-326.
[4] Quoted in Catherine Dold, "Hormone Hell," DISCOVER Vol. 17
No. 9 (September, 1996), pgs. 52-59.
[5] Joseph L. Jacobson and Sandra W. Jacobson, "Sources and
Implications of Interstudy and Interindividual Variability in the
developmental Neurotoxicty of PCBs," NEUROTOXICOLOGY AND
TERATOLOGY Vol. 18 No. 3 (1996), pgs. 257-264.
[6] Abraham Brouwer and others, "Functional aspects of
developmental toxicity of polyhalogenated aromatic hydrocarbons
in experimental animals and human infants," EUROPEAN JOURNAL OF
PHARMACOLOGY, ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY SECTION
293 (1995), pgs. 1-14.
[7] E. Lonky and others, "Neonatal Behavioral Assessment Scale
performance in humans influenced by maternal consumption of
environmentally contaminated Lake Ontario fish," JOURNAL OF GREAT
LAKES RESEARCH Vol. 22 No. 2 (1996); in press.
[8] Per Eriksson and Anders Fredriksson, "Neonatal exposure to
2,2',5,5'-tetrachlorobiphenyl causes increased susceptibility in
the cholinergic transmitter system at adult age," ENVIRONMENTAL
TOXICOLOGY AND PHARMACOLOGY (1996), pgs. 217-220. And: Per
Eriksson and Anders Fredriksson, "Developmental neurotoxicty of
four ortho-substituted polychlorinated biphenyls in the neonatal
mouse," ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY (1996), pgs.
155-165. And: Edel Holene and others, "Behavioral Effects of
Pre-and Postnatal Exposure to Individual Polychlorinated Biphenyl
Congeners in Rats," ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Vol.
14 No. 6 (1995), pgs. 967-976. And: Susan L. Schantz and others,
"Spatial Learning Deficits in Adult Rats Exposed to
ortho-Substituted PCB Congeners during Gestation and Lactation,"
FUNDAMENTAL AND APPLIED TOXICOLOGY Vol. 26 (1995), pgs. 117-126.
[9] Yueliang L. Guo and others, "Growth Abnormalities in the
Population Exposed in Utero and Early Postnatally to
Polychlorinated Biphenyls and Dibenzofurans," ENVIRONMENTAL
HEALTH PERSPECTIVES Vol. 103 SUPPLEMENT 6 (September 1995), pgs.
17-122.
[10] Jane E. Brody, "Study Finds Lasting Damage From Prenatal PCB
Exposure," NEW YORK TIMES September 12, 1996, pg. A14.
[11] Ana Maria Evangelistia de Duffard and Ricardo Duffard,
"Behavioral Toxicology, Risk Assessment, and Chlorinated
Hydrocarbons," ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 104
SUPPLEMENT 2 (April 1996), pgs. 353-360. And: Deborah C. Rice,
"Neurotoxicty of Lead, Methylmercury, and PCBs in Relation to the
Great Lakes," ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 103
SUPPLEMENT 9 (December 1995), pgs. 71-87.
[12] Gunilla Lindstrom and others, "Workshop on Perinatal
Exposure to Dioxin-like Compounds. I. Summary," ENVIRONMENTAL
HEALTH PERSPECTIVES Vol. 103, SUPPLEMENT 2 (March, 1996), pgs.
135-142.
[13] Kristin Bryan Thomas and Theo Colborn, "Organochlorine
Endocrine Disruptors in Human Tissue," in Theo Colborn and
Coralie Clement, editors, CHEMICALLY-INDUCED ALTERATIONS IN
SEXUAL AND FUNCTIONAL DEVELOPMENT: THE WILDLIFE/HUMAN CONNECTION
[Advances in Modern Environmental Toxicology Vol. XXI]
(Princeton, N.J.: Princeton Scientific Publishing Co., 1992),
pgs. 342-343.
CORRECTION
In RACHEL'S #511, we said, "However, most species disappear in
natural aquatic ecosystems at higher pH values (more acidic
conditions) than predicted by laboratory tests, thus suggesting
that, in ecosystems, additional stresses enhance the effects of
acidification." Obviously, this should have said "(less acidic
conditions)."
Descriptor terms: pcbs; polychlorinated biphenyls; fish; central
nervous system damage; great lakes; lake michigan; lake ontario;
children; joseph jacobson; sandra jacobson; endocrine disrupters;
lead; netherlands; oswego; edward lonky; monsanto;
################################################################
NOTICE
Environmental Research Foundation provides this electronic
version of RACHEL'S ENVIRONMENT & HEALTH WEEKLY free of charge
even though it costs our organization considerable time and
money to produce it. We would like to continue to provide this
service free. You could help by making a tax-deductible
contribution (anything you can afford, whether $5.00 or
$500.00). Please send your contribution to: Environmental
Research Foundation, P.O. Box 5036, Annapolis, MD 21403-7036.
--Peter Montague, Editor
################################################################
BACK TO
*********************************************************************