Determination of Urinary Metabolites of Toluene and Xylenes in Paint Workers and Non-Occupationally Exposed Individuals in Saudi Arabia

Aromatic hydrocarbons such as toluene and xylenes are widely used as solvents in industrial processes, particularly in paint production, despite their known toxicity. Occupational exposure to these chemicals poses significant health risks, especially for workers in the manufacturing and application sectors. The International Agency for Research on Cancer (IARC) has reported an increased cancer risk associated with paint fume exposure, prompting regulatory agencies such as the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) to establish exposure limits. In Saudi Arabia, a key player in the petroleum and chemical industries, workers face potential exposure to these compounds. Human biomonitoring (HBM) is essential in this context, particularly in regions such as Makkah, where unique climatic conditions may influence exposure levels and biological responses. Establishing reference values for biomarkers is crucial to addressing the existing gaps in occupational exposure data in the region. This cross-sectional study design, utilizing surveys and urinary biomonitoring to assess and quantify toluene and xylene metabolites in occupationally exposed painting workers comparing to non-occupationally exposed individuals in Makkah, Saudi Arabia. The study population included 224 unexposed individuals from the general public and 108 painting workers. Structured questionnaires collected sociodemographic, occupational, and health-related data, including self-reported symptoms, while urine samples were analyzed using high-performance liquid chromatography (HPLC). Results revealed that the drowsiness (p = 0.030), tiredness (p = 0.008), poor sleep quality (p < 0.001), and stomach pain (p < 0.001), were significantly associated with occupational exposure. Toxicity-related symptoms, such as difficulty concentrating (p < 0.001), headaches (p < 0.001), blurred vision (p < 0.001), heart palpitations (p < 0.001), excessive sweating (p < 0.001), and allergic or dry skin (p = 0.001), were also significantly linked to occupational exposure. Urinary biomonitoring revealed a significant increase in urinary hippuric acid (HA) levels among exposed workers (Z = 5.84, p < 0.001).