Toxic Metals in Cosmetics: A Review of Analytical Determination, Human Health Risk and International Regulation for Safe Use

Cosmetics are widely used even for daily usage. Raw materials and industrial machines used for their preparation are inevitably affected by contamination from metals, because these species are ubiquitous in the world. For instance, nickel, lead and cadmium are frequently unintentionally added to cosmetics as impurities during manufacturing. In fact, some metals are very dangerous for human health. This is true over safe limits of concentration even in the case of metals which are essential for human metabolism. Moreover, heavy metals may accumulate in the body over time and repetitive product applications, leading to significant exposure levels. International regulation about metals in cosmetics is very heterogeneous from Country to Country. Moreover, in many Countries the regulation is incomplete or absent. In some cases, regulations provide safe limits, but the analytical techniques useful to check for those limits are not indicated. In other cases, the safe limits are below the limit of detection of available analytical methodologies, hence the development of new methods is necessary. For these reasons, a deep knowledge of metals content in personal care products and cosmetics is necessary using reliable, and high-throughput, sensitive and selective analytical assays are needed. The present review proposes an exhaustive focus on what are the metals of interest, and what is the state of the art about analytical methodologies suitable to detect these toxic metals in cosmetics and personal care products (PCPs). This review would also be a stimulus to solicit International Organizations to fill the gap of the lack of strict and comprehensive laws regulating the maximum allowable concentrations for an increasing number of contaminants in these matrices, especially considering their enormous daily use.