Is Vigna radiata (L.) R. Wilczek a suitable crop for Lindane contaminated soil?

Lindane (γ-hexachlorocyclohexane) is an organochlorine pesticide recently included in the Stockholm list of persistent organic pollutants for global elimination. However, India is still allowed to use lindane for combating vector borne diseases. Because of its large scale utilization during the last few decades, lindane residue is reported from almost all agricultural soils of India. So there is an immediate need to monitor the accumulation of lindane residue in crop plants growing in contaminated systems and suitable strategies should be taken to prevent the possible entry of lindane in food chain. Therefore, in the present study, we studied the accumulation and translocation of lindane in Vigna radiata (L.) R. Wilczek (Mung bean), a widely grown legume in India as a cheap source of protein. The test plant was grown in four different concentrations of lindane viz. 5, 10, 15 and 20 μg g−1 soils and harvested at 15 and 45 days and at maturity. The experimental results showed that irrespective of the exposure days, the accumulation of lindane in plant parts were linearly correlated (r2 = 0.915) with the lindane concentration in soil. However, the lindane concentration in soil significantly reduced the growth and yield (number of pods, pod length, number of seeds and seed weight) of the test plants at 95% confidence level (α = 5). At maturity, the concentration of lindane in whole plant (root + shoot + leaf + seed) growing at four different concentrations were reached up to 3.8, 9.4, 13.5 and 17.79 μg g−1 dry matter, respectively. Worryingly, lindane residue was found in the seeds of test plants grown at 10, 15 and 20 μg g−1 soils and the concentrations were detected as 0.2, 0.4 and 0.89 μg g−1 dry seed, respectively. Most importantly, the residue level detected in the edible part was higher than the maximum residue limit set by WHO and Codex Alimentarious Commission (0.1 μg g−1). Thus our study suggests that Mung bean is not a suitable crop for medium to high level lindane contaminated soil.