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Pesticide residues monitoring

Pesticide residues monitoring
In order to supervise the use of pesticides, many countries have national monitoring programs of pesticide residues. The QuEChERS method combined with tandem mass detection has been widely used in analysis of pesticide residues. QuEChERS is a simple and straightforward sample preparation technique for multi-residues screening. There are several kinds of conditions of pesticide residue analysis. Test results of pesticide residues concentration lower than LOQ the limit of quantitation of the analytical methods are considered not detectable. A test result higher than MRL leads to violations of tolerance. Sometimes, pesticide residues are detected in produces which government has not established a MRL for it. This is called violations of no tolerance.
This table shows the summary results of pesticide monitoring programs from the USDA, the United States Department of Agriculture, in 2015, About 10 thousands of fruit and vegetable samples has been analyzed in this program. Multiple pesticide residues have been observed in most commodities except sweet corn. In the product marked in red, over fifty percent of them are detected more than three kinds of pesticides in one sample. And strawberries are more likely to be contaminated with multiple pesticide residues. This slide show the sample numbers with pesticide residue violations. The left figure shows that the sample numbers of pesticide residues exceeding the MRL and strawberries are the most likely to exceed safe limits.
Violations of no tolerance were the most common type of violation Which were detected in fourteen selected commodities as shown in the right figure. Most of the violations of no tolerance were found in Spinach. Since multiple pesticide residues are observed in most commodities, here are several ways to minimize your intake of pesticides. First, purchase in-season fruit and vegetables when you go to markets. Off-season production may increase the risk of pesticide exposure if crops are more affected by pests and diseases and the farmers do not handle pesticides correctly. Buying and eating food in its correct season is a cost-saving way to enjoy the health benefits of seasonal produce.
Second, eat a variety of foods from a variety of sources which can help you to get a better mix of nutrients and to reduce the exposure risk to a single pesticide. Buying certified agricultural products is an easy way to ensure product safety due to using pesticides properly. In Taiwan, agricultural certification standards include Certified Agricultural Standards, Good Agricultural Practice, Traceable Agricultural Product and traceability QR codes. The certified logos indicate that the agricultural products were produced in compliance with these standards, which can help us to choose food with the high quality and safety. Next, be sure to wash all produce thoroughly before eating, even that which is labeled organic or that which you plan to peel.
First, discard outer leaves of leafy vegetables because contact pesticides are applied to the outer surfaces of crops. Second, gently wash fruits and vegetables under running water and rub them clean. firm fruit and vegetables such as potatoes, can be scrubbed with a soft brush. Even fruit that doesn’t look dirty, such as berries and tomatoes, they should be washed thoroughly. And washing with water is effective. There is no need to use soap or a produce wash. Soak in water for ten to twenty minutes to reduce water-soluble pesticides, but avoid a long soak to prevent water-soluble nutrients from leaching out. After soaking, wash fruit and vegetables under running water again.
Although Washing food is important to reduce pesticide residues on the surface, no washing method is hundred percent effective for removing all pesticide residues especially those penetrating deep into plants. Food processing is another important way to reduce pesticide residues. The effective processing ways include Peeling and heating, such as blanching, cooking, and frying. So next time, if you want to make a green salad, make sure to wash all vegetables thoroughly, because there is no more effective process to reduce pesticide residues after washing. Finally, you should be concerned about pesticide residues in food, but not so concerned that you stop eating these foods. I would like to wrap up my talk with this final thought.
Thank you for staying with me through all of that.

After the introduction of how to evaluate the toxicity of pesticides. Continuous monitoring of pesticide residues is needed in policy.

To reduce the risks of poisoning ourselves, we should minimize pesticide residues in foods. In this video, Prof. Hou will talk about some useful tips.

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Introduction to Nutrition and Food Safety

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