Assessment of Heavy Metals and pH Levels in Commercial Blonde Hair Dyes Marketed in Benghazi, Libya: Human Dermal Exposure and Health Risk Assessment

Abstract

In the environment, heavy metals are present in the air, water, food, and many consumer products. Some heavy metals are essential to the human body, but only in high concentrations. Heavy metals play an important role in the human organism and are called essential minerals, while others are not known to be beneficial to our health, or, more precisely, are toxic. The toxicity of heavy metals to humans is clearly caused by long-term or high-level exposure to common pollutants. High concentrations of heavy metals may cause health problems. It is known that heavy metals can be found in many cosmetic products, and one of these is hair color, where they can enter the body through the skin and the root of the hair. Various health problems can be caused if their concentrations are high in the body. From this point, it is more important to determine the content of heavy metals. So, this paper aims to determine the concentrations of heavy metals such as (Pb, Cr, Cd, Zn, Ni, Fe, and Mn) in hair dyes. Also, blonde hair dyes are used to produce brighter and darker hair shades. Ten blonde hair dyes produced in 2026 by different manufacturers were collected from different pharmacies located in Benghazi, Libya, and analyzed using wet digestion. The analysis of heavy metals was done by the atomic absorption spectrophotometry method. In all the analyzed blonde hair dye samples, heavy metals were detected, and the overall mean (n=10) concentration for each of Pb, Cr, Cd, Zn, Ni, Fe, and Mn was: 0.076, 1.335, 0.026, 5.774, 0.921, 16.652, 0.522 mg\Kg. The concentrations of heavy metals in the analyzed hair colours were different. The measured levels of heavy metals in hair dye have been compared with data from studies carried out in other countries. Evaluate the pH of the various brands of hair dyes available in the market. Most hair dyes have a pH in the 10.00-11.5 range. In general, the pH is outside the range of pH values for normal skin and hair pH values. Approximations of health risks in adults were obtained using the systemic exposure dose (SED), Hazard Index (HI), and Cancer Risk (CR) for adults. The CR values were mostly within the acceptable range, suggesting that the carcinogenicity risk was low. The Hazard Quotient (HQ) and HI in each sample were below the threshold of 1, indicating low non-carcinogenic risk. This study strongly recommended minimizing long-term exposure to toxic elements in hair dye formulations and ensuring safer consumer products.