Studies on the use of pesticides in southwest Nigeria have revealed a substantial rise in a variety of pesticide-related illnesses, including mental impairment and reproductive problems. Those who work in agriculture and are regularly exposed to pesticides are the most impacted. The World Health Organization (WHO) predicts that three million severe pesticide poisoning episodes occur globally each year, with at least 300.000 deaths and 99% of cases occurring in low- and middle-income nations. The effects of longer-term exposure to pesticides on health are not yet precisely estimated. <b>Objectives</b><b>: </b>To this end, the objective of this study is to assess the knowledge of pesticide residues and common pesticides in grain-based food (brown and white beans, yellow and white maize, brown millet and rice) about pesticide use in selected markets of Southwest Nigeria. <b>Methods</b><b>: </b>A total of 240 respondents were selected from four states (Ado-Ekiti, Ibadan, Osun and Ondo) with the aid of structured questionnaire and interview guide using purposive sampling technique. The markets were Oja-titun (market) Ile-Ife, Osun; Alesinloye Market Ibadan, Oyo; Oja Oba, Ado-Ekiti, Ekiti; and Oja Oba, Akure Ondo State. The identification and quantification of pesticide residues was done using a Varian 3800/4000 gas chromatograph mass spectrometer while 60 structured questionnaires were administered to respondents including food merchants, buyers/consumers as well as food vendors. Data were analysed using descriptive statistics. <b>Results</b><b>: </b>The experiment was conducted from November 2020 to November 2021. Up to 50.4% never read instructions on pesticide application while a shared 24.8% read them always and occasionally. The number of respondents who never read the instructions were particularly high in Ekiti and Ondo, up to 52.5% of the respondents in Ekiti do not know whether or not they are exposed to pesticides during application. Also, majority of the respondents never attended any professional training on pesticide application, this amounted to 79.3%. Most people were not aware that unsafe pesticide application is harmful to human health. Similarly, a wide variety of symptoms were reported by respondents following pesticide application or consumption of grains, these included headaches and dizziness, itching and redness of the eyes, skin allergy, diarrhea, and stomach disorder, vomiting and loss of appetite, weakness of the body, asthma, permanent skin patches, shortness of breath, excessive sweating. Millet recorded the highest number of OCP residues while maize had the lowest. On the contrary, maize had the highest number of OPP and carbamate residues while millet had the lowest number of OPP residues. Meanwhile, maize, rice and beans had only one carbamate pesticide residue. <b>Conclusions</b><b>: </b>According to the study's conclusions, farmers who can only get information from agricultural extension officials should receive urgent and immediate attention for raising awareness. Additionally, extensive IPM training programs must be created with the intention of disseminating precautions for protecting human health and a healthy agro-ecosystem. In order to find more effective pest management methods that utilize less pesticides, it is crucial to reevaluate the pesticide residues and common pesticides found in grains in the targeted markets. To reduce farmers' exposure to pesticides, it is also required to establish personal protective measures, special educational initiatives, and legislation promoting the use of safer pesticides. <b>Significance and novelty</b><b>: </b>This study gives policymakers a comprehensive understanding of the ways that may be utilized to close the significant knowledge gap on pesticide residues in grains and provides an insight into the knowledge of pesticide residues and common pesticides in grains.
