Objectives-To investigate the incidence of allergy to laboratory animals (ALA) during the first two years of employment, and to study the effect on ALA of atopy and sensitisation. Methods-A follow up prospective study of ALA at the Zeneca (formerly ICI) Research Laboratories. Results-The incidence of the disease during the first year of employment has remained at about 10% since the mid1980s. This compares with an incidence of 37% in the early 1980s. The reduction in incidence and its maintenance at a lower level is thought to be due to the introduction and management of improved engineering controls, working practices, and educational programmes designed to reduce exposure to allergens from laboratory animals. The underlying incidence of immunological sensitisation to animals ( Two of these prospective studies also investigated the influence of one or more atopic indicators on the development of ALA.26 In both of these studies, it was concluded that the exclusion of people with atopy from working with animals could not be justified, as for every case of ALA that would theoretically be prevented, at least three people who would never develop the problem would also be denied employment.At ICI (now Zeneca), since the mid-1980s there has been a coordinated process to try to maintain or reduce further the incidence of ALA by means of improved engineering controls and the use of personal protective equipment as well as by health surveillance and educational programmes. We report one outcome of this, namely the incidence of ALA during the first two years of employment in a group of 200 scientists and technicians recruited by ICI since the last study (from 1987-1990). The paper also considers the influence of atopy and of pre-existing sensitisation to laboratory animals on the development of ALA.

Objective-To study mortality among 1785 employees of a factory that produced cellulose triacetate film base at Brantham in the United Kingdom. Also, to investigate patterns of mortality after exposure to methylene chloride; in particular, mortality from liver and biliary tract cancer, lung cancer, pancreatic cancer, and cardiovascular disease. Subjects and methods-All male employees with a record of employment at the film factory in 1946-88. A total of 1473 subjects worked in jobs that entailed exposure to methylene chloride. The mean duration of exposure was nine years at 19 ppm (eight hour time weighted average). Results-In the cohort, 334 deaths were identified up to 31 December 1994. Mortalities for the cohort were compared with national and local rates and expressed as standardized mortality ratios (SMR). In the subcohort of workers exposed to methylene chloride, substantially reduced mortalities compared with national and local rates were found for all causes, all cancers, and the principal cancer sites of interest. The significantly reduced lung cancer mortalities in exposed workers (SMR 48) seemed to reflect the restrictions on smoking at the workplace. In contrast, mortality from ischaemic heart disease in exposed workers, although lower than national rates (SMR 92), was slightly increased compared with local rates. However, mortality from ischemic heart disease was lower in active employees (SMR 83) where a direct effect of exposure to methylene chloride should be concentrated. No in service mortality due to ischaemic heart disease was found in workers with the highest cumulative exposure (>i 800 ppm-years). Conclusions-The study provided no indication that employment at the plant, or exposure to methylene chloride, had adversely affected the mortalities ofworkers.

Objectives-To study mortality among 4324 workers at two United Kingdom factories, Darwen, Lancashire and Wilton, Cleveland, producing polymethyl methacrylate (PMMA) sheet. The Darwen factory is still active, but the Wilton one was closed in 1970. Also, to investigate patterns of mortality after exposure to methyl methacrylate; in particular, mortality from colon and rectal cancer. Results-In the Darwen cohort, 622 deaths were identified and a further 700 deaths in the Wilton cohort. Mortalities for the cohort were compared with national and local rates and expressed as standardised mortality ratios (SMRs). In the subcohort of Darwen workers with more than minimal exposure to MMA, reduced mortalities compared with national and local rates, were found for all causes (SMR 94), and colorectal cancer (SMR 92), but mortality from all cancers was slightly increased (SMR 104). No relations were found with cumulative exposure to MMA. In the subcohort of Wilton workers, mortality from all causes of death was significantly reduced (SMR 89), but mortality from all cancers (SMR 103) and colorectal cancer (SMR 124) were increased. The excess of colorectal cancer was confined to employees with less than 1 year of employment. Conclusion-The study provided no clear evidence that employment at the factories or exposure to MMA had adversely affected the mortalities of workers. (Occup Environ Med 2000;57:810-817)