Abstract:
Irrigation with Microcystin-LR (MC-LR) and Cylindrospermopsin (CYN) contaminated water poses a potential to accumulate MC-LR and CYN in plant tissues. Oryza sativa is the staple food source in Sri Lanka which contribute more than half of the caloric intake. However, the accumulation of CYN and MC-LR in rice grains were not understood in CKDu prevalence areas. CYN and MC-LR are the potent cyanotoxins that affect the function of kidney, liver and suspected as one of the possible causes for CKDu in Sri Lanka. The aim of the present study was to find the accumulation status of MC-LR and CYN in 117 Oryza sativa grains collected from CKDu highprevalent Medirigiriya Mahathalakolawewa (36) and Ambagaswewa (31). CKDu non-prevalent Angunakolapallassa (50) in Hambanthota district was selected as the control area. MC-LR and CYN were quantified by the High Performance Liquid Chromotography (HPLC). Bioaccumulation of CYN and MC-LR in O. sativa was ranged from 0.1×102 ± 0.09 µgkg-1 – 2.30×102 ± 23 µgkg-1, 0.1×102 ± 0.09 µgkg-1 – 1.55 ×102 ± 13 µgkg-1 in rice samples which were collected from Medirigiriya –Mahathalakolawewa. In Medirigiriya - Ambagaswewa, the concentrations of MC-LR and CYN ranged between 0.1×102 ± 0.01 µgkg-1 – 2.70×102 ± 18 µgkg-1 and 5 ± 0.02 µg kg-1 to 130 ± 1.13 µg kg-1 respectively. The human health risk of CYN and MC-LR were ranged between 0.05×10-2 ± 0.001 µgkg-1day-1 –13.5×10-2 ± 0.001 µgkg-1day-1 and 0.05×10-2 ± 0.001 µgkg-1day-1 – 7×10-2 ± 0.01 µgkg-1day-1 respectively. However, the-none of rice grains were positive for CYN and MC-LR collected from Angunakolapellessa. According to the TDI values given by WHO (MCLR=0.04 µgkg-1day-1, CYN=0.02 µgkg-1day-1), 84% exceeded the TDI value for CYN where 55% exceeded the TDI value for MC-LR. Thus, the results of the study revealed that consumption of cyanotoxin contaminated Oryza sativa has a potential risk on accumulation of CYN and MC-LR in human body. Thus, public awareness should raise in order to minimise this risk of CYN and MCLR in human body.
