Analytical approach, dissipation pattern and risk assessment of pesticide residue in green leafy vegetables: A comprehensive review.

The category of 'leafy vegetables' comprises a wide range of plants, including cabbage, lettuce, leeks, spinach, Swiss chard and kale, and it forms a significant component of the human diet. Typically, leafy vegetables are low in calories and fat, are great sources of vitamins, protein, dietary fibre and minerals (including iron, calcium, and nitrates), and are rich in phytochemicals. To counter the impact of pests on vegetables, a broad variety of pesticides are used. Because of their large surface areas, leafy vegetables are expected to have high residual pesticide levels. As such, a sound analytical approach is needed to detect and quantify residue levels that are equal to or lower than the maximum residue limits, thus rendering the products safe for consumption. Overall, leafy vegetables consumed raw (after a tap water wash only), boiled or steamed contribute 2% of total vegetable consumption globally, and they might have a comparatively greater influence on health than cereal ingestion. Consequently, in this review paper, we highlight the importance of leafy vegetables, the pesticides that are commonly used on them and various analytical techniques, including sample preparation, extraction, clean-up and final detection. The effects on dissipation patterns, pre-harvest residue limits and safety/risks imposed by various pesticides are also reviewed and discussed. In conclusion, environmentally friendly extraction methods coupled with high-throughput techniques with greater reproducibility and lower uncertainty are needed for quantifying residues in leafy vegetables at very low concentrations. Commercial and household food preparation, such as washing, peeling, blanching and cooking are effective in removing most of the pesticide residues that are loosely attached on vegetables.
(Copyright © 2017 John Wiley & Sons, Ltd.)