A nested case-control study of methemoglobinemia risk factors in children of Transylvania, Romania.

Abstract

In this nested case-control study, we investigated the risk factors for methemoglobinemia (MHG) in 71 children in the Transylvania region of Romania. This study was unique in that the exposures for cases and controls were calculated as continuous values and were reported in milligrams per kilogram per day of nitrate/nitrite based on careful dietary reconstruction and environmental sampling. This procedure allowed us to compare point estimates of nitrate/nitrite exposure with other continuous, categoric, and ranked risk factors such as the presence or absence of diarrheal disease, reported severity of diarrheal disease, the use of vitamin supplements, the presence, absence, and/or duration of breast-feeding, and whether or not first-generation relatives experienced MHG. Analysis of these factors and exposure levels using both univariate and multivariate whole-model tests was performed to understand the relative significance of risk factors at varying levels of exposure to the development of MHG. Univariate and multifactorial analysis of risk factors for MHG underscored that, for this population, MHG is most strongly associated with nitrate/nitrite exposure through the dietary route (p = 0.0318), via feeding of formula and tea made with water containing high levels of nitrates, and that breast-feeding protects infants younger than 6 months of age (p = 0.0244). Our findings also raise questions about the role of diarrheal disease in the development of MHG, as likelihood ratios (likelihood 4.323, p = 0.0376) and multifactorial analysis indicated a significant role for diarrheal disease for some individuals.

Does Exposure to Nitrate in Drinking Water Contribute Anything the Effect of Water Chlorination on Children Methemoglobin Levels?

“…We did not retain neither covariates such as boiling drinking water, antecedent acute diarrheas, lettuce, celery, coriander, and parsley since they were not significantly associated with abnormal MetHb level (p-value > 0.25) nor age (a surrogate measure of the period of exposure to drinking water nitrate). Infants (0 -6 months) were considered as a reference group since breastfeeding protects from methemoglobinemia [17]. However, the small number of infants in the current study (13 participants: 9 were only breastfed; 4 were breastfed and also used formula) did not allow us to consider the age as a potential risk factor of abnormal MetHb level.…”

“…A study physician conducted physical examinations to screen for taken medications, use of herbs, and household chemicals, that could affect MetHb level, acute diarrhea (current and antecedent one) as infection that is thought to cause methemoglobinemia [14,15], hypertension, heart disease, regular vitamin C intake which has a protective effect [16,17], weight, height, and signs (noise and tips of ears, around the month and eyes, and fingers can appear blue from lack of oxygen) and symptoms including cyanosis, headaches, fatigue and dizziness, that depend on MetHb level.…”

World water resources: Trends, challenges, and solutions

“…In other areas, where the access to improved water sources and sewerage is better, there often remains lingering divides between urban and rural populations with the rural poor subsisting on shallow, supposedly 'improved' wells which are still highly contaminated and have completely unacceptable water contamination profiles by the standard of North American and Western European city dwellers (Table 1), as some data from recent research in rural, central-eastern Europe indicate (Zeman et al 2005). Levels of nitrates, fecal coliforms, and parasites can remain a serious problem contributing to childhood morbidity and mortality (Zeman et al 2002a(Zeman et al , 2005. UNICEF estimates indicate that during the 1990s urban access to safe drinking water was about 90%, rural access was only about 62%, and while 79% of urban dwellers had adequate sanitation services, that figure was only about 25% for those living in rural areas (UNESCO 2003).…”

Physicochemical and Microbiological Assessment of Selected Hand-Dug Wells for Water Quality in Ilesa Metropolis, Southwest Nigeria

“…It supports drinking water supply, for man, livestock, irrigation, industrial and many commercial activities (Vesilind, 1993). Groundwater is generally less susceptible to contamination and pollution when compared to surface water bodies (Zaman, 2002).…”