Rates of regression and progression of dysplastic lesions in the nasal mucosa in nickel workers: a Markov model approach

• Published in: Science of the total environment 1994-06, Vol.148 (2), p.311-318
• Main Authors: Boysen, Morten, Downs, Angela M., Rigaut, Jean Paul, Torjussen, William, Högetveit, Arne Christian, Andersen, Ivar, Berge, Steinar R., Solberg, Lars Aage, Abeler, Vera M., Reith, Albrecht, Voss, Ragnar, Farstad, Torkjel
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Carcinogenesis; Epidemiology; Histology; Human nasal mucosa; Humans; Longitudinal Studies; Markov Chains; Medical sciences; Models, Biological; Nasal Mucosa - drug effects; Nasal Mucosa - pathology; Nickel; Nickel - adverse effects; Nose Neoplasms - chemically induced; Nose Neoplasms - epidemiology; Nose Neoplasms - pathology; Occupational Diseases - chemically induced; Occupational Diseases - epidemiology; Occupational Diseases - pathology; Occupational Exposure - adverse effects; Occupational Exposure - prevention & control; Otorhinolaryngology. Stomatology; Precancerous; Precancerous Conditions - chemically induced; Precancerous Conditions - epidemiology; Precancerous Conditions - pathology; Remission Induction; Time Factors; Tumors; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/0048-9697(94)90409-X

Nasal epithelial dysplasia is considered a precancerous state. From 1976 through 1989, regular screening for such lesions has been performed among workers at the Falconbridge nickel refinery in Kristiansand. The longitudinal data thus obtained have been evaluated to ascertain to what extent, if any, pre-existing dysplasia can regress when exposure to nickel is reduced. A total of 418 pairs of observations were available from 243 workers. Interpretation of the data is complicated by the fact that dysplasia may remain undetected in small biopsies and the probability of detection of existing dysplasia was, therefore, incorporated into the two-state Markov model. Transition probability rates were estimated by maximum likelihood. The results suggest that regression of dysplasia has taken place and that regression rates increased with time. This finding probably reflects a decreased exposure resulting from a combination of a reduction in airborne nickel, improved personal hygiene and allocation of workers with dysplasia to work in areas with lower nickel exposure. Our results indicate that the chance of developing carcinomas related to nickel exposure is reduced. There are, however, indications that dysplasias continue to develop at a low rate.