Main conclusion | Origin | SIGN grade | Study type | Exposure/occupation | Subjects | |
Anhydrides | ||||||
Grammer [42] | Before introduction of respirators, annual incidence for asthma was 10% In 7 yrs of follow-up after respirators, highest annual incidence was 2% Conclusion: respirators can reduce incidence of occupational asthma, in workers exposed to HHPA | Literature search | 2+ | Prospective cohort study following intervention (introduction of respirators) | HHPA | 66 new workers who made HHPA |
Diisocyanates | ||||||
Tarlo [43] | In 1983, Ontario, Canada mandated medical surveillance programme for workers exposed to diisocyanates, followed by retrospective assessments to determine benefits Frequency of diisocyanate asthma workers' compensation claims (both number and percentage of all occupational asthma claims) peaked in 1988, and then declined in 1993 Conclusion: medical surveillance programme contributed to the positive change, but reduced diisocyanate exposures and increased awareness of problem by workers and physicians may have also contributed to decline | Literature search | 3 for surveillance and 2+ for case–control study within case series | Registry based ecological study Case series from workers' compensation claims for occupational asthma attributed to diisocyanates in province of Ontario, Canada | Diisocyanate exposure (study had exposure above threshold limit value as readout parameter) | Number of claims varied by year, from 55–58 claims per yr in 1988–1990, to 19–20 claims per yr in 1992–1993 |
Flour and other bakery exposure | ||||||
Smith [41] | The intervention reduced bread improver levels by better exhaust ventilation, respiratory protection, education, respiratory health surveillance and dust sampling There was an overall reduction in the incidence of new cases of symptomatic sensitisation, from 2085 per million employees per yr in the first 5 yrs of the surveillance programme, to 405 per million employees per yr in the subsequent 5 yrs Symptomatic sensitisation incidence was not related to total inhalable dust levels Conclusion: the strategy of targeting bread improver exposure is an effective approach for preventing symptomatic sensitisation in bread bakeries | Literature search | 2- | Prospective intervention in UK food company Based on surveillance data in combination with a triage approach that was not validated | Bakery workers, flour millers exposed to flour and enzymes, especially fungal amylase | >3000 workers per year under surveillance |
Meijster [40] | Changes in exposure over time varied between sectors and jobs For bakeries: modest downward trend of -2% per yr for flour dust and -8% per yr for amylase For flourmills: -12% per yr for flour dust and no significant trend for amylase For ingredient producers: results generally nonsignificant, but indicated a reduction in flour dust and increase in fungal α-amylase Modest increase in use of control measures and proper work practices reported in most sectors, especially local exhaust ventilation and decreased use of compressed air Conclusion: the magnitude of the observed reductions in exposure levels indicates that the sector-wide intervention strategy implemented had a limited overall effect | Literature search | 2+ | Sector-wide intervention programme, with education on good work practices, and nonrandomised before and after evaluation of exposure to wheat and fungal α-amylase | Bakery workers, flour millers, bakery ingredient workers | 1770 personal exposure measurements generally including data on flour dust and fungal α-amylase levels, taken in four surveys (1993, 2001, 2005 and 2007) |
Detergent enzymes | ||||||
Cathcart [44] | At five production facilities in the UK dust and enzymes levels in 1969–1993, lung function of workers in 1972–1991, and cases of occupational asthma in 1968–1992 were evaluated Exposure groups were defined by job history Enzyme levels declined over the study period Changes in FEV1 and FVC showed no consistent trends in relation to enzyme exposure The annual number of cases of enzyme allergy and asthma declined | Literature search | 2- | Registry-based study, case series, ecological | Detergent enzyme exposure in production facilities | 731 male workers |
Schweigert [45] | Variety of controls introduced across detergent enzyme manufacturing industry Decrease in number of occupational asthma cases in Latin American and North American detergent enzyme manufacturing sites in 1969–1998, but no denominators indicated | Literature search | 4 | Review article with minimal data and documentation | Detergent enzyme manufacturing industry | Unclear |
Laboratory animal allergy and asthma | ||||||
Botham [46] | Prospectively studied incidence of allergy to laboratory animals in 383 workers exposed to rodents and to rabbits Intervention was introduction of a site order and code of practice for working with animals, and an education programme Concurrent with the intervention, incidence of allergy after 1 yr of exposure to animals fell from 37% in 1980–1981 to 20% in 1982, 10% in 1983 and 12% in 1984 Atopy increased risk of allergy in first year of exposure but not in second or third years of exposure | Literature search | 2- | Intervention study with longitudinal, repeated measurements | Laboratory animal workers with exposure to rodents and rabbits | 383 workers |
Fisher [47] | Intervention programme included education, engineering controls, administrative controls, use of personal protective equipment, and medical surveillance Prospective survey of 5 yrs of data to determine effect programme (1991–1995) At the start of the programme, prevalence of laboratory animal allergy was 12–22%, and then 0% in the last 2 yrs of the 5-yr observation period Conclusion: laboratory animal allergy is preventable through the implementation of a comprehensive effort to reduce exposure to allergens | Literature search | 2- | Comprehensive intervention programme with longitudinal, repeated measurements | Laboratory animal workers | 159 employees |
SIGN: Scottish Intercollegiate Guidelines Network; HHPA: hexahydrophthalic anhydride; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity.