Arsenic in rice and vegetables: Human body loading, perception and mitigation strategy

Arsenic (As) elevated groundwater irrigation and its bioaccumulation in rice and vegetables is a significant health concern worldwide. Global ninety percent of rice-producing Asian countries largely depend on As contaminated groundwater irrigation for rice and vegetable production. Researchers are endeavoring to invent As mitigating strategies to combat this terrible hazard; all their striving have ensued without adequate grassroots information about farmers' perception of the As accumulation scenario in their crops. Again, tracing As intake, particularly from rice and vegetables by biomarker analysis, has also been poorly addressed. At the same time to combat the problem, the best combination of irrigation management and suitable rice variety altering As content in grains must be ensured. This study aims to assesse farmers’ perception, investigate the human exposure to arsenic due to rice and vegetable consumption, and suggest As mitigating strategy in the naturally As affected area.

Results reveal that 25 percent of farmers have a good perception. In contrast, the rest have poor to moderate perception, particularly about the effect of contaminated groundwater irrigation on rice & vegetables and mitigation measures. The correlation coefficient demonstrates ten out of sixteen characteristics have significant positive association with perception at a 1% significance level. Farmers' knowledge (74.6%), direct participation in farming (8.2%), information sources (4.5%), participant education (0.7%), and organizational participation (0.8%) together explain 88 percent variances in perception. Path analysis depicts that direct participation in farming presents the highest positive total effect (0.855) and direct effect (0.503), whereas information sources show the highest positive indirect effect (0.624).

Keeping the study of farmers’ perception, current health risk status was assessed. For the health risk assessment, 100 farmers were purposively selected who met certain criteria and donated their scalp hair, and provided their field soil, irrigation water, vegetables, and rice samples. Data on sociodemographic characteristics and food consumption were collected in-person through administering questionnaires. The mean As content in soils, irrigation water, vegetables, rice, and scalp hairs exceeded the permissible limit, while As content was significant at 5%, 0.1%, 1%, 0.1%, and 0.1% probability levels, respectively, in all five study locations. Arsenic levels in scalp hair showed a significant positive correlation (p≤0.01) with that in rice and vegetables. The bioconcentration factor (BCF) is less than one and significant at a 1% level of probability. The RfD limit for As is larger than the average daily intake (ADI). The hazard quotient (HQ) of grains and vegetables is greater than 1. According to the maximum incremental lifetime cancer risk (ILCR), there is a threshold risk of 1.6 per 1000 individuals and a considerable risk of 2.8 per 100 people, respectively. The PCA analysis revealed that the first principle component (PC1), which is dominated by As in irrigation water, grain, and vegetables, explains 91.1 percent of the overall variance. While rice and vegetables As exhibit larger variety in similarity on the dendrogram, it has been discovered that vegetables As contributes more to human body loading than grain As.

However to suggest an As mitigating strategy in rice, a field trial was conducted. The field trial results revealed that As content in different portions of the paddy plant was significantly different (P<0.001) with irrigation practices and rice varieties. AWD irrigation with TSG accumulated lower As in rice grains than CF-AsW for both varieties. Data showed that AWD-TSG practice led to 61.37% and 60.34% grain As reduction for BRRI dhan28 and BRRI dhan29, respectively, compared with CF-AsW. For Principle Component Analysis (PCA), the first principle component (PC1) explained 91.7% of the variability and irrigation water As, soil total and available As, straw As, root As, and husk As were the dominating parameters. With significant (P< 0.05) variation in yields between the genotypes, AWD increased grain yield by 29.25% in BRRI dhan29 Compared with CF. However, translocation factor (TF) and bioconcentration factor (BCF) for both varieties were less than one for all the treatments. To combat the As accumulation problem, the best combination of irrigation management, i.e., AWD-TSG with BRRI dhan29, could be adopted as an As–safe practice for rice cultivation without compromising yields. All rights reserved.