The term "smokeless tobacco" refers to the consumption of unburned tobacco, in the form of chewing, spitting, dipping, and snuff. Consumers chew the tobacco in the mouth and spit out the juice that builds up. Nicotine and other constituents are absorbed in the lining of oral cavity. People of many regions, including India, Pakistan, other Asian countries, and North America, have a long history of smokeless tobacco use. Approximately 28 chemical constituents present in smokeless tobacco are carcinogenic in nature, among which nitrosamine is the most prominent [1].People mostly use paan and gutkha due to a lack of awareness and education. They are not aware of the harmful effects associated with the use of these substances, and it has been reported that these products are consumed for perceived beneficial effects, such as mouth freshening, aid in digestion, germ-killing, astringency, mood enhancement, tension relief, and oral cleaning [1]. Gutkha is sweet in taste, and children consider it to be a form of candy. Many people believe that gutkha is a mouth freshener, but its pleasant taste and sweetness aggregate microbes, causing damage to teeth. The use of paan and gutkha is difficult to control in most countries where it is widespread, and their extensive use leads to oral cancer [2]. The consumption of smokeless tobacco and areca nut is high in South Asian countries in the form of paan. In various South Asian languages, paan simply means "leaf. " Various inSmokeless tobacco consumption, which is widespread throughout the world, leads to oral submucous fibrosis (OSMF), which is a long-lasting and devastating condition of the oral cavity with the potential for malignancy. In this review, we mainly focus on the consumption of smokeless tobacco, such as paan and gutkha, and the role of these substances in the induction of OSMF and ultimately oral cancer. The list of articles to be examined was established using citation discovery tools provided by PubMed, Scopus, and Google Scholar. The continuous chewing of paan and swallowing of gutkha trigger progressive fibrosis in submucosal tissue. Generally, OSMF occurs due to multiple risk factors, especially smokeless tobacco and its components, such as betel quid, areca nuts, and slaked lime, which are used in paan and gutkha. The incidence of oral cancer is higher in women than in men in South Asian countries. Human oral epithelium cells experience carcinogenic and genotoxic effects from the slaked lime present in the betel quid, with or without areca nut. Products such as 3-(methylnitrosamino)-proprionitrile, nitrosamines, and nicotine initiate the production of reactive oxygen species in smokeless tobacco, eventually leading to fibroblast, DNA, and RNA damage with carcinogenic effects in the mouth of tobacco consumers. The metabolic activation of nitrosamine in tobacco by cytochrome P450 enzymes may lead to the formation of N-nitrosonornicotine, a major carcinogen, and micronuclei, which are an indicator of genotoxicity. These effects lead to further DNA damage and, eve...

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Pesticides are among the most important chemicals used in agriculture sector. However, their extensive use has polluted the environment and increased human vulnerability to various chronic diseases. Pesticide exposure causes genetic and epigenetic modifications, endocrine disruption, mitochondrial dysfunction and oxidative stress. Areas covered: This review is based on the literature studies currently reported on pesticide-induced toxicity and the protective role of melatonin. Scientific databases such as PubMed, Scopus and Web of Science were searched using keywords 'pesticide' and 'melatonin' up to January 2016. Full length articles related to animal and human exposure were retrieved. A total number of 181 records were obtained, and after excluding the duplicates, 97 papers were further screened on the basis of relevance to the topic. Expert opinion: Melatonin as a broad-spectrum antioxidant is able to penetrate cellular compartments specifically the mitochondria. It is a potent free radical scavenger with low toxicity and desirable solubility in organic and aqueous phases. We are of the opinion that melatonin is a promising agent in minimizing organ injuries induced by pesticides.