Despite the utility of pesticides, their occurrence within the environment can pose significant threats to human, animal, and ecological health. In a recent study, a group of researchers looked to incorporate PBD to determine the interaction of multiple factors on the ultrasonic cleaning of products for pesticide removal.
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An Overview of the Use of Pesticides
Pesticides, which are also known as parasitoids, play an essential role in the agricultural industry to control pests that can threaten the quantity and quality of crops.
There are several types of pesticides that can be used, some of which include disinfectants, fungicides, herbicides insecticides, and rodenticides.
Aside from preventing pests from disrupting normal agricultural processes, pesticides are also important for preventing a number of public health problems that can arise in the presence of pests. Infectious diseases like the West Nile virus, Lyme disease, and rabies can be carried and spread by disease-carrying species like mosquitoes, ticks, and rodents.
Furthermore, contamination of crops with microorganisms like bacteria, viruses, and protozoans can cause numerous diseases to spread. Therefore, the use of pesticides is essential to maintain the integrity of our public health systems.
Health Risks of Pesticide Residues
For humans, pesticides can enter the body through oral, dermal, inhalation, and/or ingestion routes.
Although the absorption of pesticides and other harmful chemicals varies according to each exposure route, these substances can cause a wide range of adverse effects from mild headaches to more severe symptoms like comas, convulsions, or death.
Furthermore, chronic exposure to low doses of pesticides can also cause long-term effects, as evident from the use of paraquat and rotenone, both of which are pesticides that have been found to significantly increase the risk of Parkinson’s disease in exposed individuals.
The use of pesticides can also have significant impacts on environmental health as a result of their ability to contaminate soil, water, turf, and other vegetation.
For example, when a large amount of pesticides are used to treat soils, these chemicals can reduce the proliferation of various microorganisms that are beneficial to the soil.
This phenomenon closely resembles the overuse of antibiotics in humans, as the overuse of fertilizers and pesticides can reduce the concentrations of healthy bacteria and fungi that ultimately lead to soil degradation.
In addition to their impact on the health of humans and the environment, pesticides can also reach non-target organisms as these substances travel in the soil, air, and water.
Chlorpyrifos, for example, is a contaminant that is often found in urban streams and is known to be highly toxic to fish. Animals that are able to survive despite the presence of these contaminants are often at great risk of bioaccumulating these chemicals.
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The bioaccumulation of such toxic contaminants not only has adverse effects on the reproductive and immunological functions of animals, but can also eventually reach human consumption and elicit adverse effects through the ingestion of these species.
Traditional Methods to Analyze Pesticide Cleaning
Aside from washing fruits and vegetables before consumption, there are several additional ways in which pesticide residues can be removed from produce. Typically, these processes can be classified into physical, chemical, and biological methods.
When considering pesticides or insecticides that contain arsenic, for example, physical approaches that can be used to remove this contaminant include diluting contaminated and uncontaminated soils together to reduce the concentration of arsenic within the soil to acceptable levels.
Soil washing with different concentrations of chemicals is another method that can physically remove this contaminant from soil.
Various chemicals can also be used to extract arsenic from soil; however, these methods are often highly expensive and thus cannot be applied on a large scale.
Additional chemical remediation approaches that can be applied include adsorption through specific media, immobilization, modified coagulation along with filtration, precipitations, immobilizations, and complexation reactions.
Another highly efficient and simple method that can be used to remove pesticide residues is ultrasonic washing.
The removal of pesticides by this eco-friendly friendly method is determined by various factors, some of which include the acidity of the cleaning water solution, the physical, chemical, and endogenous properties of the pesticides, as well as the frequency and power of the ultrasonic waves.
Plackett-Burman Design and Response Surface Methodology
The Plackett-Burman design (PBD) is a classical screening method that can be used to reduce the number of experimental groups. More specifically, PBD is a small-sized two-level factorial experimental design that can identify important physicochemical parameters from a given number of large variables.
This systematic design of experiments (DOE) approach utilizes various mathematic tools to determine the importance of certain variables in an effort to control them and optimize their performance. As a result, PBD is often utilized in investigations that look to assess the combination of large effects of various factors on a given process.
Response Surface Methodology (RSM) is often coupled with PBD to further optimize selected parameters.
To this end, RSM is a design technique that involves the collection of statistical techniques to build models, evaluate the impact of certain factors on the given process, and ultimately predict the optimal conditions for these factors.
Utility of Plackett-Burman Design in Ultrasonic Cleaning
In a study published in the Journal of the Science of Food and Agriculture, a group of researchers aimed to incorporate PBD to determine the interaction of multiple factors on the ultrasonic cleaning of products for pesticide removal.
To this end, the researchers utilized PBD to assess five independent factors of pH, ultrasonic cleaning time, temperature, initial residual concentration, and volume of water.
How do ultrasonic cleaner work? Functionality of a high-performance ultrasonic bath
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The researchers of this study utilized both regression fitting and response surface in RSM to determine the influence of each of these variables on the pesticide removal rate of ultrasonic cleaning.
Taken together, the authors of the current study found temperature to have a significant effect on the ability of ultrasonic cleaning to effectively remove triadimefon.
In fact, it was observed that a higher temperature improved the removal rate of this contaminant.
Comparatively, the four other factors of pH, cleaning time, initial residual concentration, and water volume were found to have a greater impact on the ability of this method to remove boscalid.
By manipulating each of these variables, the researchers observed that when the contaminant was present in an alkaline environment, combined with an increase in the initial residual concentration and cleaning time and a reduction in water volume, the removal rate of boscalid was significantly greater.
The utility of both PBD and RSM in the current study provided evidence for how to improve the conditions under which the ultrasonic cleaning of pesticides from crops can be conducted.
As a result, the researchers anticipate that future applications of this methodology could be used to determine the best possible conditions for removing other potentially harmful contaminants from products to ultimately improve the health and safety of humans.
References and Further Reading
EPA. (2021). Why We Use Pesticides [Online]. https://www.epa.gov/safepestcontrol/why-we-use-pesticides.
Parkinsons.org. (2021). The Relationship Between Pesticides and Parkinson’s [Online].: https://www.apdaparkinson.org/article/the-relationship-between-pesticides-and-parkinsons/.
Damalas, C. A., Koutroubas, S. D. (2016). Farmers’ Exposure to Pesticides: Toxicity Types and Ways of Prevention. Toxics 4(1). doi:10.3390/toxics4010001.
Aktar, M. W., Sengupta, D., Chowdhury, A. (2009). Impact of pesticides use in agriculture: their benefits and hazards. Interdisciplinary Toxicology 2(1); 1-12. doi:10.2478/v10102-009-0001-7.
Lim, K. T., Shukor, M. Y., Wasoh, H. (2014). Physical, Chemical, and Biological Methods for the Removal of Arsenic Compounds. BioMed Research International. doi:10.1155/2014/503784.
Ekpenyong, M. G., Antai, S. P., Asitok, A. D., Ekpo, B. O. (2017). Plackett-Burman Design and Response Surface Optimization of Medium Trace Nutrients for Glycolipopteide Biosurfactant Production. Iranian Biomedical Journal 21(3); 249-260. doi:10.18869/acadpub.ibj.21.4.249.
Li, X., Xu, H., Liu, F., et al. (2021). Utilizing Plackett-Burman design and response surface analysis to optimize ultrasonic cleaning of pesticide residues from rape. Journal of the Science of Food and Agriculture. doi:10.1002/jsfa.11545.