Kohl, a traditional eye cosmetic long used in Oman for both cosmetic and cultural purposes, has come under scientific scrutiny due to concerns about potential health risks linked to its composition. Passed down through generations, this black eye makeup has been widely applied not only for beauty but also with the belief that it protects the eyes. In some Omani households, it is even applied to newborns as part of customary care. However, research conducted over the past several decades has raised concerns about the presence of toxic substances, particularly lead, in locally produced kohl.

The earliest scientific investigation dated back to 1998, when a team of researchers analyzed 47 samples of kohl primarily collected in Oman, with comparative samples from other countries. Using techniques including X-ray powder diffraction and scanning electron microscopy, they identified that among 18 Omani-made kohls, five were primarily composed of galena (lead sulfide, PbS), a lead-containing mineral. The other samples included amorphous carbon and hematite (an iron oxide). The samples from other countries also contained a range of compounds, some of which included lead-based components such as galena and minium (lead tetroxide, Pb₃O₄). The study warned physicians to consider traditional kohl use as a potential source of undiagnosed lead exposure, especially in children presenting unexplained symptoms.

Nearly two decades later, a follow-up study published in 2017 provided a more detailed chemical analysis of 14 different types of Omani-made kohl from various regions within the country. Employing advanced methods such as energy-dispersive X-ray microanalysis and inductively coupled plasma mass spectroscopy, the researchers identified six mineral-based kohls. Four of these, locally referred to as lasif, cold ethmid, hot ethmid, and original ethmid, contained high levels of lead primarily in the form of galena. Two others, named red ethmid and black ethmid, were composed mainly of iron oxides such as hematite, magnetite, and goethite. The remaining eight samples were carbon-based, including one produced by charring date stones, while the others were soot derived from burning diverse materials.

Both studies highlighted the potential health implications of lead exposure due to traditional kohl use, particularly for children. Lead poisoning can manifest with symptoms that may not immediately suggest the cause, complicating diagnosis. Supporting these findings, a meta-analysis published in the Pan African Medical Journal, which reviewed 14 observational studies across several countries, found a statistically significant correlation between kohl use and elevated blood lead levels in children, though it noted considerable variability in the data.

While kohl remains an enduring element of Omani cultural heritage and family customs, this body of research underscores the need for awareness of its possible health risks. The findings call for continued dialogue between health professionals, communities, and policymakers to address the risks associated with traditional cosmetics while respecting cultural practices.