Sadeq Mina, Moe Christine L, Attarassi Benaissa, Cherkaoui Imad, Elaouad Rajae, Idrissi Larbi
National Institute of Hygiene, Department of Toxicology, Industrial Hygiene and Environmental Health, 27 Avenue Ibn Battouta, BP 769, Rabat, Morocco.
Int J Hyg Environ Health. 2008 Oct;211(5-6):546-54. doi: 10.1016/j.ijheh.2007.09.009. Epub 2007 Dec 26.
Nitrate is ubiquitous in environmental media (air, water and soil) and other sources (some medicines, inorganic fertilizers and household's chemicals). It is a hemoglobin-oxidizing agent that can cause methemoglobinemia. The effect of nitrate on infants is well known but less is known about nitrate-induced methemoglobinemia in young children.
Two cross-sectional studies were carried out in Salé, Morocco to determine the prevalence of methemoglobinemia among 411 infants and children aged 1-7 years in two adjacent areas that were similar in terms of the air quality, available vegetables and medicines but different in terms of the drinking water quality (nitrate-contaminated well water versus municipal water).
In the exposed area, nitrate concentration was measured in 78 wells and ranged from 15.39 to 246.90mg/l as NO3-. Nitrate levels were higher than 50mg/l in 69.2% of the surveyed wells, and 64.2% of the participants were drinking nitrate contaminated well waters. The prevalence of methemoglobinemia among study children was 36.2% in the exposed area, and 27.4% in the non-exposed area. Study children drinking well water with a nitrate concentration >50mg/l were significantly more likely to have methemoglobinemia than those drinking well water with a nitrate concentration <50mg/l (p=0.001 at 95% CI=[1.22-2.64]) or than those drinking municipal water (p<0.01 at 95% CI=[1.16-2.21]). In the exposed area, the mean methemoglobin (MetHb) level increased with age (R2= 0.79, p=0.04), whereas in the unexposed area, the mean MetHb level remained relatively stable in the first 6 years of life (R2=0.21, p=0.44). Mean MetHb was normal when the nitrate concentration in water was below 50mg/l as NO3-, and reached an abnormal level, when the nitrate concentration in water ranged between 50 and 90mg/l as NO3-. This last level was statistically similar to mean MetHb at nitrate level above 90mg/l as NO3- (up to 246.9mg/l as NO3-). No association was observed between methemoglobinemia prevalence and gender. This is the first study about methemoglobinemia conducted in Morocco.
硝酸盐在环境介质（空气、水和土壤）及其他来源（某些药物、无机肥料和家用化学品）中普遍存在。它是一种可导致高铁血红蛋白血症的血红蛋白氧化剂。硝酸盐对婴儿的影响广为人知，但对于幼儿因硝酸盐引起的高铁血红蛋白血症却知之甚少。
在摩洛哥的萨勒开展了两项横断面研究，以确定在两个相邻地区1至7岁的411名婴儿和儿童中高铁血红蛋白血症的患病率。这两个地区在空气质量、可得蔬菜和药物方面相似，但饮用水质量不同（受硝酸盐污染的井水与市政供水）。
在暴露地区，对78口水井进行了硝酸盐浓度测量，范围为15.39至246.90mg/l（以NO₃⁻计）。69.2%的被调查水井硝酸盐水平高于50mg/l，64.2%的参与者饮用受硝酸盐污染的井水。暴露地区研究儿童中高铁血红蛋白血症的患病率为36.2%，非暴露地区为27.4%。饮用硝酸盐浓度>50mg/l井水的研究儿童比饮用硝酸盐浓度<50mg/l井水的儿童（95%置信区间为[1.22 - 2.64]时p = 0.001）或饮用市政供水的儿童（95%置信区间为[1.16 - 2.21]时p < 0.01）患高铁血红蛋白血症的可能性显著更高。在暴露地区，平均高铁血红蛋白（MetHb）水平随年龄增加（R² = 0.79，p = 0.04），而在未暴露地区，生命的前6年平均MetHb水平保持相对稳定（R² = 0.21，p = 0.44）。当水中硝酸盐浓度低于50mg/l（以NO₃⁻计）时，平均MetHb正常，当水中硝酸盐浓度在50至90mg/l（以NO₃⁻计）之间时，达到异常水平。这一水平在统计学上与硝酸盐水平高于90mg/l（以NO₃⁻计，最高达246.9mg/l以NO₃⁻计）时的平均MetHb相似。未观察到高铁血红蛋白血症患病率与性别之间存在关联。这是在摩洛哥进行的第一项关于高铁血红蛋白血症的研究。
