Microcystin-LR bioaccumulation and depuration kinetics in lettuce and arugula: Human health risk assessment.
Microcystin-LR (MC-LR) is one of the most toxic and common microcystins (MCs) variant found in aquatic ecosystems. Little is known about the possibility of recovering microcystins contaminated agricultural crops. The objectives of this study were to determine the bioaccumulation and depuration kinetics of MC-LR in leaf tissues of lettuce and arugula, and estimate the total daily intake (ToDI) of MC-LR via contaminated vegetables by humans. Arugula and lettuce were irrigated with contaminated water having 5 and 10μgL(-1) of MC-LR for 7days (bioaccumulation), and subsequently, with uncontaminated water for 7days (depuration). Quantification of MC-LR was performed by LC-MS/MS. The one-compartment biokinetic model was employed for MC-LR bioaccumulation and depuration data analysis. MC-LR was only accumulated in lettuce. After 7days of irrigation with uncontaminated water, over 25% of accumulated MC-LR was still retained in leaf tissues of plants treated with 10μgL(-1) MC-LR. Total daily toxin intake by adult consumers (60kg-bw) exceeded the 0.04μgMC-LRkg(-1) limit recommended by WHO. Bioaccumulation was found to be linearly proportional to the exposure concentration of the toxin, increasing over time; and estimated to become saturated after 30days of uninterrupted exposure. On the other hand, MC-LR depuration was less efficient at higher exposure concentrations. This is because biokinetic half-life calculations gave 2.9 and 3.7days for 5 and 10μgL(-1) MC-LR treatments, which means 29-37days are required to eliminate the toxin. For the first time, our results demonstrated the possibility of MC-LR decontamination of lettuce plants.
Department of Biological Sciences, Luiz de Queiroz College of Agriculture, University of São Paulo, Av. Pádua Dias, 11, São Dimas, CEP 13418-900 Piracicaba, SP, Brazil; Botany Graduate Program, Rural and Federal University of Pernambuco, R. Dom Manoel de Medeiros, S/N, Dois Irmãos, CEP 52171-030 Recife, PE, Brazil.
Micheline Kézia
MK
Cordeiro-Araújo
Department of Biological Sciences, Luiz de Queiroz College of Agriculture, University of São Paulo, Av. Pádua Dias, 11, São Dimas, CEP 13418-900 Piracicaba, SP, Brazil.
Mathias Ahii
MA
Chia
Institute of Physics, University of São Paulo, Rua do Matão Travessa R Nr.187, CEP 05508-090, Cidade Universitária, SP, Brazil; FESP - São Paulo Engineering College, Av. Nove de Julho, 5520, CEP 01406-200 São Paulo, SP, Brazil.
João Dias de Toledo
JDT
Arruda-Neto
CENA, University of São Paulo, Av. Centenário, 303, CEP 13400-970 Piracicaba, SP, Brazil.
Valdemar Luiz
VL
Tornisielo
CENA, University of São Paulo, Av. Centenário, 303, CEP 13400-970 Piracicaba, SP, Brazil.
Franz Zirena
FZ
Vilca
Department of Biological Sciences, Luiz de Queiroz College of Agriculture, University of São Paulo, Av. Pádua Dias, 11, São Dimas, CEP 13418-900 Piracicaba, SP, Brazil; Botany Graduate Program, Rural and Federal University of Pernambuco, R. Dom Manoel de Medeiros, S/N, Dois Irmãos, CEP 52171-030 Recife, PE, Brazil. Electronic address: mbitt@usp.br.
Maria do Carmo
MDC
Bittencourt-Oliveira
D001427:Bacterial Toxins / Q000378:metabolism*; D019607:Brassicaceae / Q000737:chemistry*; D004032:Diet; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D007700:Kinetics; D018545:Lactuca / Q000737:chemistry*; D008387:Marine Toxins; D052998:Microcystins / Q000378:metabolism*; D018570:Risk Assessment
D001427:Bacterial Toxins; D008387:Marine Toxins; D052998:Microcystins; C057862:cyanoginosin LR
Bioaccumulation; Biokinetic parameters; Contaminated irrigation water; Depuration; MC-LR; Vegetables