Subject: CLEAN AIR:  STUDY LINKS INFANT DEATHS TO PARTICULATES

     Infants in cities with the highest levels of particulate air
pollution are 26% more likely to die from sudden infant death
syndrome (SIDS) than those that live in areas with cleaner air,
according to a new study by federal scientists.  The study found
that infant mortality due to respiratory failure is 45% greater in
the "most polluted" cities.

     The study, which was conducted by scientists at the US EPA and
the Centers for Disease Control's National Center for Health
Statistics, comes "at a critical juncture" in the debate over the
EPA's proposal to tighten air-quality standards for ozone and
particulates.  It will be published this month in the journal
Environmental Health Perspectives.

     Researchers analyzed 4 million births in 86 cities between
1989 and 1991, examining infants between the ages of 28 days and
one year.  The study's principal author, the EPA's Tracey Woodruff,
said dirty-air cities showed significantly higher infant mortality
due to SIDS, respiratory failure and all other causes.  The higher
mortality persisted even after accounting for other possible
influences such as weather, date and time of birth, birth weight,
mothers' smoking habits, race and education.

     In the case of SIDS -- a term used to describe the sudden,
unexplained death of infants -- the findings "are consistent with
other studies" that link infant deaths to exposure to second-hand
cigarette smoke, which contains minute particles.  The overall
findings were also consistent with studies that show "strong
associations between" particulates and premature death in adults.


CRITICS WANT TO SEE CAUSE AND EFFECT

     The study was "not designed to establish how tiny particles
kill babies."  Critics say such studies demonstrate only
associations between events, not causes and effects.
     "Nonetheless, even skeptics were impressed with the
thoroughness of the study."  Robert Drew of the American Petroleum
Institute questioned whether indoor air pollution might be more to
blame, since babies spend most of their time inside. But he added:
"I'm really struck.  My reaction is skeptical, and I hope it's not
true" (Gary Polakovic, Riverside [CA] Press- Enterprise, 6/7).


Older Abstracts
~~~~~~~~~~~~~~~

1973
Greenberg, M. A., K. E. Nelson, et al. (1973). "A study of the
relationship between sudden infant death syndrome and environmental
factors." American Journal of Epidemiology 98(6): 412-22.

1981
Hoppenbrouwers, T., M. Calub, et al. (1981). "Seasonal relationship
of sudden infant death syndrome and environmental pollutants."
American Journal of Epidemiology 113(6): 623-35.
     Evidence that chronic hypoxia precedes death from sudden
infant death syndrome (SIDS) is mounting. Prolonged exposure to
moderate levels of pollutants could be a contributing factor to
hypoxia. Levels of carbon monoxide (CO), sulphur dioxide (SO2),
nitrogen dioxide (NO2) and hydrocarbons (HC) are highest in the
winter when incidence of SIDS is increased. SIDS cases in Los
Angeles County were correlated with daily mean levels of these
pollutants, temperature, barometric pressure and monthly lead
levels with the aid of time series analyses. Peaks in CO, SO2, NO2,
HC and lead preceded the seasonal increase in SIDS by seven weeks.
Theoretical considerations, such as the hypoxia-inducing effects
of CO, support the hypothesis that this temporal relation has
functional significance. Three additional findings provided
evidence for this hypothesis: 1) SIDS infants born during months
of low pollution lived longer than those born during months of high
pollution. 2) SIDS infants born in a district with low pollution
lived longer than those born in a district with high pollution. 3)
The bimonthly rate of SIDS was directly proportional to the level
of CO pollution to which the infants had been exposed between
conception and two months of age. The role of pollution levels as
a predisposing factor in risk for SIDS cannot be summarily
dismissed.

1990
Loscher, W., C. Einspieler, et al. (1990). "[Air pollution and
sudden infant death in Graz 1982 to 1987]." Wiener Klinische
Wochenschrift 102(4): 115-7.
     We correlated the incidence of the sudden infant death
syndrome (SIDS) and the degree of air pollution in each district
of Graz over a time period of five years. The degree of air
pollution was derived from a mapping of epiphytical lichen
vegetation by Grill et al. (1988). We found an increased incidence
of SIDS in districts with poor air quality. Although this result
is not statistically significant a possible increase in SIDS risk
because of air pollution cannot be excluded. Some
pathophysiological explanations are discussed.

1991
Penna, M. L. and M. P. Duchiade (1991). "Air pollution and infant
mortality from pneumonia in the Rio de Janeiro metropolitan area."
Bulletin of the Pan American Health Organization 25(1): 47-54.
     The authors report the results of an investigation into the
possible association between air pollution and infant mortality
from pneumonia in the Rio de Janeiro Metropolitan Area. This
investigation employed multiple linear regression analysis
(stepwise method) for infant mortality from pneumonia in 1980,
including the study population's areas of residence, incomes, and
pollution exposure as independent variables. With the income
variable included in the regression, a statistically significant
association was observed between the average annual level of
particulates and infant mortality from pneumonia. While this
finding should be accepted with caution, it does suggest a
biological association between these variables. The authors'
conclusion is that air quality indicators should be included in
studies of acute respiratory infections in developing countries.

1992
Bobak, M. and D. A. Leon (1992). "Air pollution and infant
mortality in the Czech Republic, 1986-88." Lancet 340(8826):
1010-4.
     An ecological study of infant mortality and air pollution was
conducted in the Czech Republic. Routinely collected data on infant
mortality and air pollution in the period 1986-88 were analysed for
the 46 of the 85 districts in the republic for which both were
available. The independent effects of total suspended particulates
(TSP-10), sulphur dioxide (SO2), and oxides of nitrogen (NOx)
adjusted for district socioeconomic characteristics, such as
income, car ownership, and abortion rate, were estimated by
logistic regression. We found weak positive associations between
neonatal mortality and quintile of TSP-10 and SO2. Stronger
adjusted effects were seen for postneonatal mortality, with a
consistent increase in risk from the lowest to the highest TSP-10
quintile (p < 0.001). Weaker and less consistent evidence of a
positive association with NOx (p = 0.061) was observed. The
strongest effects were seen for postneonatal respiratory mortality,
which increased consistently from lowest to highest TSP-10 quintile
(p = 0.013). There was also a suggestion of a positive association
with SO2 (p = 0.062). The highest to lowest quintile risk ratios
for postneonatal respiratory mortality were 2.41 (95% Cl 1.10-5.28)
for TSP-10, 3.91 (0.90-16.9) for SO2, and 1.20 (0.37-3.91) NOx. The
specificity of the association between air pollution quintile
(especially TSP-10) and postneonatal respiratory mortality is
consistent with the known effects of air pollution on respiratory
disease morbidity in children. These ecological associations
require confirmation in an individually based study.

1995
Knobel, H. H., C. J. Chen, et al. (1995). "Sudden infant death
syndrome in relation to weather and optimetrically measured air
pollution in Taiwan [see comments]." Pediatrics 96(6): 1106-10.
     OBJECTIVE. To examine the possible role of weather and air
pollution in sudden infant death syndrome (SIDS) and suffocation.
METHODS. Poisson regression analysis was carried out to measure the
association between daily rates of SIDS per 1000 live births and
daily average values of visibility and temperature in Taiwan
between 1981 and 1991. The optimetrical measure of air pollution
was used to represent pollution over a whole area rather than at
a point source. RESULTS. Mortality from SIDS per 1000 live births
was 3.3 times greater in the lowest category of visibility on the
day of death than in the highest category; this rate ratio was 3.4
for the average visibility during the 9 days before death.
Adjustment for population size, season, level of urbanization,
incidence of deaths from respiratory tract infections, temperature,
air pressure, sunshine, rainfall, relative humidity, and windspeed
increased these rate ratios to 3.8 and 5.1, respectively. This
suggests that the relationship between air pollution and SIDS is
not biased by ecological confounders. For temperature the rate
ratios were between 3.3 and 4.0. CONCLUSIONS. Our findings confirm
the association of climatic temperature and air pollution with
SIDS.
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