Comparative Determination of Lead, Cadmium, Mercury, and Arsenic in Commercial Dairy Products by Atomic Absorption Spectrometry and Inductively Coupled Plasma Optical Emission Spectrometry.

Heavy metal contamination of dairy products represents a significant food safety concern because of the potential for chronic dietary exposure and associated health risks. This study determined the concentrations of lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As) in commercial milk, white soft cheese, and yoghurt marketed in Egypt using atomic absorption spectrometry (AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES), followed by dietary exposure and pollution index assessments. A total of 150 samples (50 of each dairy product) were collected from retail markets and analyzed following acid digestion. AAS detected Pb concentrations ranging from 0.021 to 0.194 mg/kg, Cd from 0.010 to 0.186 mg/kg, Hg from 0.033 to 0.060 mg/kg, and As from 0.122 to 0.154 mg/kg. Corresponding ICP-OES concentrations ranged from 0.013 to 0.182 mg/kg for Pb, 0.0092 to 0.114 mg/kg for Cd, 0.012 to 0.038 mg/kg for Hg, and 0.097 to 0.132 mg/kg for As. The two analytical techniques showed consistent patterns of variation among dairy matrices, although systematic method-dependent differences were observed, with ICP-OES generally yielding lower concentrations than AAS with relative differences ranging from 6.19% to 76.00%, depending on the metal and dairy matrix. Estimated daily and weekly intakes of all investigated metals were below internationally recognized health-based guidance values for adult consumers. However, pollution index analysis revealed that Pb and Cd concentrations exceeded the maximum permissible limits in all dairy products, while Hg exceeded the regulatory limit only in yoghurt, remained at the permissible limit in milk, and complied with the regulatory limit in white soft cheese. No regulatory maximum permissible limit has been established for As in these dairy products. These findings demonstrate the usefulness of both AAS and ICP-OES for trace-element determination while emphasizing the importance of rigorous method validation and continuous monitoring to ensure the safety of dairy products and protect public health.