Nitrate Quantification in Fresh Vegetables in Shanghai: Its Dietary Risks and Preventive Measures

Fan Luo, Xiao-Juan Yan, Xue-Feng Hu (), Li-Jun Yan, Ming-Yang Cao and Wei-Jie Zhang
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Fan Luo: School of Environmental & Chemical Engineering, Shanghai University, Shanghai 200444, China
Xiao-Juan Yan: School of Environmental & Chemical Engineering, Shanghai University, Shanghai 200444, China
Xue-Feng Hu: School of Environmental & Chemical Engineering, Shanghai University, Shanghai 200444, China
Li-Jun Yan: School of Environmental & Chemical Engineering, Shanghai University, Shanghai 200444, China
Ming-Yang Cao: School of Environmental & Chemical Engineering, Shanghai University, Shanghai 200444, China
Wei-Jie Zhang: School of Environmental & Chemical Engineering, Shanghai University, Shanghai 200444, China

IJERPH, 2022, vol. 19, issue 21, 1-13

Abstract: To investigate nitrate and nitrite content in fresh vegetables, 264 samples were randomly collected in the farmers’ markets in Shanghai, Southeast China. The results indicate that 25.0% of the fresh vegetables were critically or more contaminated by nitrate [>1440 mg/kg FW (Fresh weight)]. Generally, leafy vegetables were more highly enriched in nitrate than root-tuber and fruit vegetables. About 22.6% of the leafy vegetables had a nitrate content exceeding the limit for edible permission (>3000 mg/kg FW). Nitrite content in the fresh vegetables was all within the safe level (<1 mg/kg FW). It was estimated that the daily nitrate intake through eating vegetables in Shanghai exceeded the WHO/FAO allowable limit. The field experiment indicated that the hyper-accumulation of nitrate and nitrite in the vegetables was mainly attributed to the excessive application of chemical fertilizers. The maxima of nitrate and nitrite in the vegetables were attained one week after applying chemical fertilizer, and thus they cannot be picked for dietary use. Applying organic manure can effectively lower the risk of nitrate and nitrite contamination in vegetables. The old leaves and leaf petioles were more easily enriched in nitrate due to their weaker metabolic activity. Vegetables with high nitrate content had a high risk of nitrite toxicity during storage due to the biological conversion of nitrate into nitrite, which is easily triggered by suitable temperature and mechanical damage processing. Therefore, fresh vegetables should be stored by rapid cooling and in undamaged forms to prevent nitrite accumulation.

Keywords: vegetables; nitrate; nitrite; chemical fertilizers; storage (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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