Arsenic Accumulation in Rice Grain as Influenced by Water Management: Human Health Risk Assessment

Israt Jahan Harine,Hasina Afroz,Rounok Jahan,Mahmud Hossain,Robert J Henry,Abu Bakkar Siddique,Mohammad Rafiqul Islam,Manzer H Siddiqui,Saud Alamri,Shihab Uddin,Mohammad Anwar Hossain

doi:10.3390/agronomy11091741

Abstract

Rice is a staple food for humans and a key source of soil arsenic (As) transfer to the human food chain. As a result, it is critical to develop ways for reducing As accumulation in rice. A pot experiment with seven different water management practices was done to examine the impacts of water management on rice (cv. BRRI dhan28) growth, yield, and As accumulation in rice grain. Any health risk due to As accumulation in rice grain was also determined. The soil used in the experiment was artificially contaminated with As and the source of As was sodium arsenate (Na2HAsO4 7H2O). Water management practices affect different plant growth and yield parameters including filled grains per panicle, unfilled grains per panicle, 1000-grain weight, grain yield and straw yield of rice. The number of filled grains per panicle and 1000-grain weight were found to be at their highest in the T7 (alternate wetting and drying) condition, whereas the number of unfilled grains per panicle was at its lowest in the same treatment. The T7 also demonstrated the highest grain yield (21.08 g/pot) and straw yield (22.02 g/pot), whereas the lowest values were noted in T1 (flooding throughout the growth period). The highest As concentration in rice grain (0.52 mg kg−1) was found in T1 and the lowest As concentration in grain (0.27 mg kg−1) was found in T7. Estimation of the human health risk revealed that the non-carcinogenic risks (HQ > 1) and carcinogenic risks (CR > 1.0 × 10−4) were greatly affected by different water regimes. The rice plant grown under alternate wetting and drying condition (T7) showed the lowest health risks compared to other water management practices. Thus, alternate wetting and drying conditions are a good water management strategy for increasing rice output while reducing arsenic buildup in rice grain.

Highlights

Arsenic is a non-threshold poisonous metalloid that is found in abundance in the natural world
The longest panicle length of 22.1 cm was recorded in T1 (Flooding throughout the growth period) and the shortest panicle length (21.0 cm) was observed in T5 (Flooding from transplanting to 3 weeks before heading)
We investigated the effects of different water regimes on growth, yield, and accumulation of As in rice grain

Summary

Introduction

Arsenic is a non-threshold poisonous metalloid that is found in abundance in the natural world. Rice consumption is thought to be a major source of As exposure, accounting for more than half of the total dietary As intake [1,2,3,4]. It is extremely important throughout the Asian subcontinent, in Bangladesh, India, China, Japan, Sri Lanka, and Pakistan [5]. While continuously flooded rice systems are highly productive, they are associated with a number of issues such as high-water use [8], high methane emissions [9], and accumulation, in the grain, of heavy metals, such as mercury [10] and arsenic [11]. As accumulation in soils and crop absorption has increased as a result of this [13,14]

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