Maharjan Kishor Kumar, Dhungel Ram Prasad
Department of Environmental Science, Tri-Chandra Multiple Campus, Tribhuvan University, Kathmandu, Nepal.
Faculty of Environmental Management, Prince of Songkla University, Thailand.
Heliyon. 2024 Jul 14;10(14):e34621. doi: 10.1016/j.heliyon.2024.e34621. eCollection 2024 Jul 30.
Despite numerous studies on microplastic contamination in table salt worldwide, research focusing on Nepalese table salts is remarkably lacking. This study aims to address this gap by investigating microplastic contamination in salt samples collected from all seven provincial zones of Nepal. Our objective is to comprehensively assess the presence and characteristics of microplastics in salt sold within local markets across the country. Five salt packaging companies utilized by Nepalese consumers were identified. The collected salt samples were digested with Fenton's reagent to extract microplastics, which were then observed under a digital microscope. Using an OMAX stereomicroscope at 30× magnification and an OMAX A3503S digital camera, each microplastic was carefully identified and quantified. FTIR analysis was conducted to identify the polymer types. All tested salt samples (100 %) from both Nepalese and Indian packaging companies contained microplastics. Microplastic abundance exhibits variability among the samples, ranging from 80 to 1040 microplastics per kilogram of salt. The average value stands at 381 ± 219 microplastics per kilogram of salt sample. The distribution of microplastic concentrations within the salt samples reveals that the majority fall within the 301-400 microplastics per kilogram salt range, constituting 33 % of the total samples. Color analysis showed diverse contamination sources, while microplastic shapes included fibers (56 %), films (17 %), fragments (16 %) and pellets (11 %). Polymer type analysis confirmed the presence of polyethylene and polypropylene in tested microplastics. The study estimated that Nepalese individuals ingest an average of 1853 microplastics annually, indicating significant exposure from salt consumption. Surprisingly, factors such as storage conditions, date of salt packaging and thickness of packaging material did not significantly affect microplastic presence in the samples, suspecting manufacturing processes as the primary contributors to contamination. Therefore, the raw materials and purification practices for salt need improvement, as existing methods are insufficient to eliminate microplastics. These findings emphasize the need for further research and mitigation efforts to address microplastic contamination in Nepalese salt and its potential health impacts.
尽管全球范围内针对食盐中微塑料污染展开了大量研究，但聚焦尼泊尔食盐的研究却极为匮乏。本研究旨在通过调查从尼泊尔所有七个省收集的盐样中的微塑料污染来填补这一空白。我们的目标是全面评估该国当地市场销售的食盐中微塑料的存在情况及其特征。确定了尼泊尔消费者使用的五家食盐包装公司。收集的盐样用芬顿试剂消化以提取微塑料，然后在数字显微镜下观察。使用放大倍数为30倍的OMAX体视显微镜和OMAX A3503S数码相机，对每个微塑料进行仔细识别和量化。进行傅里叶变换红外光谱（FTIR）分析以确定聚合物类型。来自尼泊尔和印度包装公司的所有测试盐样（100%）都含有微塑料。微塑料丰度在样品之间存在差异，每千克盐中微塑料的数量在80至1040个之间。平均值为每千克盐样381±219个微塑料。盐样中微塑料浓度的分布表明，大多数微塑料浓度落在每千克盐301 - 400个微塑料的范围内，占总样品的33%。颜色分析显示了不同的污染源，而微塑料形状包括纤维（56%）、薄膜（17%）、碎片（16%）和颗粒（11%）。聚合物类型分析证实测试的微塑料中存在聚乙烯和聚丙烯。该研究估计，尼泊尔人每年平均摄入1853个微塑料，这表明通过食用盐会有大量微塑料暴露。令人惊讶的是，储存条件、食盐包装日期和包装材料厚度等因素对样品中微塑料的存在没有显著影响，怀疑制造过程是污染的主要原因。因此，食盐的原材料和提纯方法需要改进，因为现有方法不足以消除微塑料。这些发现强调需要进一步研究和采取缓解措施，以解决尼泊尔食盐中的微塑料污染及其潜在的健康影响。
