Birth weight and exposure to kitchen wood smoke during pregnancy in rural Guatemala.

Boy E, Bruce N, Delgado H.

The Micronutrient Initiative, Ottawa, Ontario, Canada.

In this study, we aimed to establish whether domestic use of wood fuel is
associated with reduced birth weight, independent of key maternal, social, and
economic confounding factors. We studied 1,717 women and newborn children in
rural and urban communities in rural Guatemala. We identified subjects through
home births reported by traditional birth attendants in six rural districts
((italic)n(/italic) = 572) and all public hospital births in Quetzaltenango city
during the study period ((italic)n(/italic) = 1,145). All were seen within 72 hr
of delivery, and data were collected on the type of household fuel used, fire
type, and socioeconomic and other confounding factors. Smoking among women in
the study community was negligible. Children born to mothers habitually cooking
on open fires ((italic)n(/italic) = 861) had the lowest mean birth weight of
2,819 g [95% confidence interval (CI), 2,790-2,848]; those using a chimney stove
((italic)n(/italic) = 490) had an intermediate mean of 2,863 g (95% CI,
2,824-2,902); and those using the cleanest fuels (electricity or gas,
(italic)n(/italic) = 365) had the highest mean of 2,948 g (95% CI, 2,898-2,998)
((italic)p (/italic)< 0.0001). The percentage of low birth weights (< 500 g) in
these three groups was 19.9% (open fire), 16.8% (chimney stove), and 16.0%
(electricity/gas), (trend (italic)p(/italic) = 0.08). Confounding factors were
strongly associated with fuel type, but after adjustment wood users still had a
birth weight 63 g lower ((italic)p(/italic) = 0.05; 95% CI, 0.4-126). This is
the first report of an association between biofuel use and reduced birth weight
in a human population. Although there is potential for residual confounding
despite adjustment, the better-documented evidence on passive smoking and a
feasible mechanism through carbon monoxide exposure suggest this association may
be real. Because two-thirds of households in developing countries still rely on
biofuels and women of childbearing age perform most cooking tasks, the
attributable risk arising from this association, if confirmed, could be
substantial.

PMID: 11781172 [PubMed - in process]

The association between exposure to air pollution from cooking fuels and health
aspects was studied in Maputo. Mozambique. Almost 1200 randomly selected women
residing in the suburbs of Maputo were interviewed and 218 were monitored for
air pollution. The fuels most commonly used were wood, charcoal, electricity,
and liquified petroleum gas (LPG). Wood users were exposed to significantly
higher levels of particulate pollution during cooking time (1200 micrograms/m3)
than charcoal users (540 micrograms/m3) and users of modern fuels (LPG and
electricity) (200-380 micrograms/m3). Wood users were found to have
significantly more cough symptoms than other groups. This association remained
significant when controlling for a large number of environmental variables.
There was no difference in cough symptoms between charcoal users and users of
modern fuels. Other respiratory symptoms such as dyspnea, wheezing, and
inhalation and exhalation difficulties were not associated with wood use.
Reducing wood use would likely improve acute respiratory health effects in wood
users and possibly improve the ambient air pollution conditions in Maputo. To
reduce the health impact of wood smoke exposure, it appears that the least
costly and quickest method would be to encourage charcoal use to a greater
extent, although high carbon monoxide levels would have to be addressed. Turning
to modern fuels is beyond the means of most these households in the short term
and could not be shown to be more effective.

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