Prenatal exposure to particulate matter (PM_2.5) and low birth weight in a Sri Lankan birth cohort

Abstract

Background.About 74% of the Sri Lankan population use biomass in the form of unprocessed wood as the primary cooking fuel. A growing body of evidence from meta-analyses and individual studies although limited by few prospective studies, report that prenatal exposure to particulate matter of size 2.5 µm (PM2.5) emissions from biomass fuel burning may be associated with low birth weight (LBW) (<2500 grams). We present results examining the association between PM2.5 and LBW in context of a birth cohort study in Sri Lanka. Methods.We followed 545 pregnant women from their first trimester until delivery and assessed outcomes at birth. Exposure to household air pollution (HAP) from biomass smoke was assessed using detailed questionnaire about fuel type, kitchen characteristics and cooking practices; two-hour measurements of kitchen PM2.5 were collected in a subset of households (n=304, 56%). Data from questionnaires and measured PM2.5 were used to estimate two-hour kitchen PM2.5 concentrations in unmeasured households. Data on covariates related to household characteristics, socio-demographic, maternal health and lifestyle factors were collected from baseline interviews. We performed linear and logistic regression analysis to evaluate the association between HAP exposure, and birth weight and LBW. Results.Of the total, 78% of the households used wood as primary or secondary fuel (n=425); households using wood had four-fold higher PM2.5 levels compared to those using LPG. In linear regression models, we found an inverse association between a 10-unit increase in PM2.5 and birth weight (β, -0.03; SE, 0.02; p, 0.06) adjusted for covariates. Similarly, categorical HAP exposure (>50% wood use) was significantly associated with birth weight as compared to LPG users (β, -0.13; SE, 0.06; p, 0.0331). In logistic regression models, a 10-unit increase in PM2.5 was associated with increased odds for LBW (OR, 1.26; 95%CI, 1.02-1.55; p, 0.0355), while the prevalence of LBW was highest among >50% wood users (OR, 2.82; 95%CI, p, 0.0124), as compared to those using >50% LPG with wood and only LPG users. The association between HAP exposure and birth weight/LBW were consistent among term births (n=486). Conclusions.The finding of a significant association between prenatal PM2.5 exposure and LBW in a lowmiddle income country (LMIC) setting where competing risk factors are minimal fills a gap in the body of evidence linking HAP from biomass smoke to LBW. These results underscore the crucial need to implement prevention and reduction of HAP exposure in LMICs where the HAP burden is high.

Household cooking fuel use and its health effects among rural women in southern India—A cross-sectional study

“…Associations between socio-demographic factors and exposure to biomass fuel was studied and it was found that women who were aged above 45 years, those with low literacy levels (0-5 years of schooling), engaged in unskilled occupations or homemakers and those from low socio-economic status were significantly associated with biomass fuel use in their lifetime. An increasing trend of using firewood was observed with increasing age in Malawi, which ranged from 33% among women of the age 17-24 years, approximately 45% among 46-55 years to 56.3% between 66-85 years (p< 0.001) [8]. A study in Sri Lanka reported that having less than 10 years of schooling (p<0.05) as well as lower family income (p<0.05) were associated with biomass fuel use which is in line with our observations (p< 0.001) [9].…”

“…World Health Organization (WHO) estimates that about 3 billion people use open fire or traditional stoves that are fuelled by kerosene and solid fuels, globally [6]. People from low socio-economic background are forced to use solid fuels as these are available easily in rural areas at a lower cost [7,8]. According to the Tracking SDG7: The Energy Progress Report 2018, if the current pattern continues, 2.3 billion people would be still using biomass in 2030 globally [9].…”

Household Air Pollution from Biomass Fuel for Cooking and Adverse Fetal Growth Outcomes in Rural Sri Lanka

“…Models were adjusted for confounders and clustered with respect to household to account for mothers with multiple children aged 5 or under. The most relevant confounders to the Sri Lankan context were identified using a directed acyclic graph (DAG) (Supplementary Figure S1) and are supported by the current literature [2,8,9,20,24]. These were household monthly income, education, area, the use of incense, the use of a vaporiser for mosquitos, and exposure to second-hand tobacco smoke.…”

“…Comparable trends are also evident in various Indian studies [13,14] and in a meta-analysis of 19 studies, in which the use of solid fuel was associated with a 35% (95% CI: 23, 48) increased risk of LBW in LMICs [11]. In a study in Sri Lanka's Western Province, a 10-fold increase in household PM 2.5 was associated with a 54% (aOR: 1.54, 95% CI: 1.12, 2.12) increased risk of LBW [9].…”

“…While the consequences of HAP are manifold, there is a growing body of evidence linking exposure with adverse antenatal outcomes such as low birth weight (LBW) and fetuses small for gestational age (SGA) [9][10][11][12][13][14][15][16][17][18][19]. Only two studies have been conducted on the association between HAP and LBW, and none on SGA in Sri Lanka to date [9,20]. The aim of this study was to investigate the association between HAP and adverse fetal growth outcomes considering primary and secondary fuel use, stove-type, and ventilation in two rural Sri Lankan communities.…”