=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #313
—November 25, 1992—
News and resources for environmental justice.
——
Environmental Research Foundation
P.O. Box 5036, Annapolis, MD 21403
Fax (410) 263-8944; Internet: erf@igc.apc.org
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CHILDREN BORN TO WOMEN LIVING NEAR OLD
DUMPS HAVE HIGHER RISK OF BIRTH DEFECTS
Pregnant women who live near hazardous waste sites have an
increased risk of bearing children with major birth defects, a
new study has concluded.[1]
Researchers at the Yale University School of Medicine and the New
York State Department of Health (NYDOH) studied 27,115 births and
concluded that, overall, women living within a mile of an
inactive dump have a 12% greater chance of bearing a child with a
major birth defect, compared to women living further than a mile
from a dump.
The researchers looked at 590 inactive dump sites in 20 northern
New York Counties. Among the 590 sites studied, 90 were ranked as
“high risk” sites because there was documented evidence that
chemicals had migrated off the sites. The study found that women
living within a mile of any of these 90 sites had a 63% greater
chance of bearing a child with a major birth defect, compared to
women living further than a mile from all of the 90 sites.
The study posed four questions: first, is residential proximity
(closeness) to dumps associated with major birth defects? Second,
are particular types of birth defects associated with proximity
to dumps? Third, do particular characteristics of dumps (for
example, documented off-site migration of chemicals) increase a
waste site’s risk to neighbors’ health? Fourth, are specific
chemical groups (such as pesticides or metals) associated with
particular birth defects as previous studies have shown (for
example, pesticides and cleft palate)? The answers to all four
questions turned out to be yes.
The Yale/NYDOH study began by examining the New York State
Congenital Malformation Registry; they found records of 9,313
infants born in 20 northern New York counties during the two-year
period 1983-1984 with major birth defects of the nervous system,
muscle and skeletal system, and skin. They omitted New York City.
The researchers then selected 17,802 normal infants from the same
20 counties born during the same time-period, to serve as
controls.
The residential locations of the mothers of all 27,115 infants
were then converted into latitude and longitude, so they could be
plotted on a map, and the distance to the nearest dump was
calculated for each residence. (Residential location was
determined to be accurate within 200 feet in 80% of the cases,
and within 1300 feet in the remaining 20 percent of cases.) Then
a comparison was made between the infants born to women who lived
within a mile of a dump, versus infants born to women who lived
more than a mile from any dump. Infants whose mothers lived a
mile or less from a dump had a 12 percent greater chance of
being born with a major birth defect.
During the second part of the study, each of the 590 dumps was
assigned a numerical hazard score, based on criteria developed by
EPA [U.S. Environmental Protection Agency] and modified by NYDOH.
Dumps considered most likely to produce toxic exposures of any
kind (through breathing, ingestion, or skin contact, via air,
water, or soil) received the highest scores. Then each individual
woman in the study was assigned an “exposure risk”–a number that
combined her proximity to a dump with the hazard score for that
dump. Then the women were split into two groups–those with a
“high exposure risk” (greater than 30) and those with a “low
exposure risk” (less than 30).
Further analysis revealed that specific kinds of birth defects
are associated with proximity to dumps, particularly birth
defects of the nervous system (29 percent more likely),
musculoskeletal system (16 percent more likely), and the skin
(also known as the body’s integument system) (32 percent more
likely). Birth defects of the digestive system and oral clefts
were not significantly associated with proximity to dumps.
The danger of birth defects is especially high near dumps where
off-site migration of wastes has been documented. Near the 90
dumps with documented off-site migration, birth defects are 63%
more likely to occur, compared to dumps where off-site migration
has not been documented.
Lastly, the study revealed that dumps containing specific kinds
of toxins were associated with specific kinds of birth defects,
thus confirming associations that have been noted in previous
studies. For example, pesticides were associated with cleft
palate in the Yale/NYDOH study. Pesticides and birth defects of
the muscular system were also associated. Metals and solvents
were each associated with nervous system birth defects. Plastics
were associated with chromosome anomalies.
Strengths of this study
Previous studies have found a connection between a mother’s
exposure to chemicals and birth defects in her offspring,[2] but
the Yale/NYDOH study is the first to examine such a large number
of births, and thus is far more convincing than previous studies.
This study also did not rely upon information provided by
individuals about themselves, so “recall bias” (errors or
distortions caused by faulty memory) was eliminated from this
study. A previous study[3] of residents near the Stringfellow
Acid Pits had shown that people near the Stringfellow dump
reported excessive occurrences of ear infections, bronchitis,
asthma, angina pectoris [heart-related chest pains], skin
rashes, blurred vision, pain in the ears, daily cough for more
than a month, nausea, frequent diarrhea, unsteady gait when
walking, and frequent urination. However, the Stringfellow
researchers were unable to rule out the effects of “recall bias”
because they relied entirely on people telling them about their
symptoms, so skeptics remained unconvinced that the study
revealed anything about real diseases caused by the nearby dump.
As the authors of the Yale/NYDOH study said, their results in
this study do not prove a cause-and-effect relationship between
birth defects and proximity to dumps, but their results “do
exhibit many characteristics of causal associations.” Each of the
four types of analysis (the four questions discussed previously)
showed increased rates of birth defects associated with proximity
to dumps. As the analysis became more specific, the associations
between dumps and disease remained similar or became even
stronger. Rates for certain birth defects associated with
chemical exposures in previous scientific studies were
statistically elevated, while other defects, with little or no
previous data to suggest a relationship with chemical exposure,
showed no increases. Finally, a kind of dose-response
relationship was apparent between proximity to higher-risk dumps
and birth defects. In other words, the closer a woman lived to a
high-risk dump, the greater were her chances of bearing a child
with a major birth defect.
Limitations of this study
This study may underestimate the number of defective births
associated with proximity to dumps for two reasons: The study did
not examine spontaneous abortions and fetal deaths–both of which
are known to be associated with human exposures to chemicals.
Furthermore, there is evidence that about 20 percent of women
move their residence during pregnancy. If this were true, it
would result in misclassification of subjects, which would weaken
the ability of the Yale/NYDOH study to discern the full effect of
living near dumps.
Lastly, the Yale/NYDOH study does not prove conclusively that
chemicals in the dumps CAUSED the birth defects because no actual
chemical exposures of women were measured. Proximity to dumps was
used as a surrogate (substitute) for exposure to chemicals. Since
no chemical exposures were actually measured, chemicals cannot be
definitely fingered as the cause of the birth defects.
Furthermore the Yale/NYDOH study did not take into account
possible differences in lifestyle (for example, tobacco and
alcohol use), occupational exposures to chemicals, and possible
exposures to chemicals from nearby industrial operations. Thus
the Yale/NYDOH study is “highly suggestive” but is not
sufficient, by itself, to prove cause and effect.
Further studies are now underway to try to remedy the
shortcomings of the Yale/NYDOH study. Unfortunately, it will be
several years, perhaps a decade, before results of these
follow-up studies will be published. In the meantime, does the
Yale/NYDOH study give us reason to be concerned about pregnant
women living within a mile of a dump? In our opinion, definitely
yes. We believe any pregnant woman who can avoid living within a
mile of a dump would be well-advised to do so. The further away
from industrial poisons, the better. The authors of the
Yale/NYDOH study said their study revealed a “small additional
risk” of bearing a child with a major birth defect. To them, a 12
percent increase is “small.” But look at it this way: the authors
say the “normal” occurrence of major birth defects in the 20
counties they studied in New York is 30 defects per 1000 live
births. Among women living within a mile of a dump, the
occurrence is 34 defects per 1000 live births–a 12 percent
increase. In the period they studied, 1983-1984, there were
506,183 live births in the 20 counties. If NONE of these women
lived within a mile of a dump, the number of spontaneous birth
defects would be 15,186. On the other hand, if ALL the women
lived within a mile of a dump, there would be 17,210 babies with
major birth defects born during the 2-year period, or
17,210-15,186=2024 excess (dump-related) birth defects in a
two-year period in the 20-county area, or about 1000 excess
(dump-related) major birth defects each year in the 20-county
area.
Would 1000 excess (dump-related) major birth defects each year in
a 20-county area be a “small” increase? DURING ONE PERSON’S
LIFETIME, THERE WOULD BE 70,000 ADDITIONAL (DUMP-RELATED) MAJOR
BIRTH DEFECTS IN THE 20-COUNTY AREA. Viewed this way, it becomes
hard to understand how the New York Department of Health can call
a 12-percent increase in major birth defects “small.”
Furthermore, from the viewpoint of any one of the mothers
involved, such an increase no doubt seems frighteningly large.
–Peter Montague, Ph.D.
Descriptor terms: health; birth defects; ny; landfilling; nydoh;
pesticides; metals; congenital malformations; congenital birth
defects; reproductive hazards; stringfellow acid pits; death;
death statistics; infant mortality;