<p>Breast milk from passive smokers may contain various harmful chemical components, primarily due to exposure to tobacco smoke. This systematic review was conducted on the chemical components of breast milk in women who were exposed to environmental tobacco smoke (ETS). English language-published papers were advanced searched without time limitation until April, 2024 in Web of Science, PubMed, and Scopus databases. A total of 1156 papers were recorded in the initial search of these databases. Finally, 18 articles met the inclusion criteria and were included. Our results showed that metals (<i>n</i> = 10) and heterocyclic compounds (<i>n</i> = 9) (cotinine, nicotine, and nornicotine) were the most commonly reported compounds in the included studies. Cotinine was the most frequently reported compound in mature milk (<i>n</i> = 9) and colostrum (<i>n</i> = 3). Among metals in mature milk, cadmium (<i>n</i> = 8) and lead (<i>n</i> = 6) are the most common compounds. Metals in colostrum were just reported in one study. The cancer risk (CR) values showed a decreasing pattern in the order of Sr &gt; Mn &gt; U &gt; Co &gt; Pb &gt; Cr &gt; As &gt; Cd &gt; Be for both aged infant groups. Parents should be encouraged to not smoke, as well as must be advised of the potential risks of ETS exposure to their babies. It is recommended that routine and continuous monitoring of probable sources of chemical contamination of breast milk due to environmental exposures should be done to discover the influencing factors and develop suitable interventions for decreasing the exposure/contamination.</p>