A novel analytical method, characterized by high specificity and strong sensitivity, has been successfully developed for the determination of 4,4′-methylene-bis-(2-chloroaniline), commonly known as “MOCA,” in human urine. It is important to note that MOCA is a well-documented carcinogen, with established toxicological evidence confirming its carcinogenicity in laboratory animals such as rats, mice, and dogs.
Prior to applying this newly developed method in real-world occupational settings, the research team first conducted a short-term preliminary study using rats. The primary objective of this preclinical study was to identify and clarify certain key peculiarities related to the urinary excretion of MOCA in the animal model—including aspects like excretion rate, metabolic pathways, and the time window for detectable levels—laying a solid scientific foundation for the subsequent application of the method in human samples.
Following the completion and validation of the preclinical study, this urine-based detection method was formally employed to assess the extent of occupational exposure to MOCA among workers in French industrial enterprises. The scope of the survey covered two main types of work scenarios closely associated with MOCA: one was the industrial production process of MOCA itself, and the other was the use of MOCA as a curing agent in the manufacturing of polyurethane elastomers, a common application scenario in the chemical and materials industries.
Through the large-scale testing of urine samples collected from workers in these scenarios, the research team found that the urinary excretion levels of MOCA exhibited a wide range of variation. Specifically, the excretion concentrations ranged from non-detectable levels—defined as less than 0.5 microgram per liter—to a maximum of 1,600 micrograms per liter. Additionally, when N-acetyl metabolites of MOCA were present in the urine samples, their concentrations were consistently and significantly lower than the concentrations of the parent compound (MOCA) in the same samples, indicating that MOCA itself is the primary form excreted in urine and a more reliable indicator of exposure.
Overall, the results obtained from this large-scale occupational exposure assessment appeared to fairly and accurately reflect the overall MOCA exposure levels of the surveyed workers, as the detected excretion levels were closely correlated with the nature of their work, the duration of exposure, and the working environment conditions. Furthermore, an important observation from the study was that after the analytical determinations were completed and targeted preventive measures were implemented in the workplaces—such as improving ventilation systems, enhancing personal protective equipment (PPE) usage, or optimizing process operations—the urinary excretion levels of MOCA in the affected workers often showed an obvious and significant decrease, demonstrating the practical effectiveness of these preventive interventions in reducing occupational exposure to MOCA.
Post time: Oct-11-2025