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Recommended Medical Screening Protocol

For people exposed to work-related allergens

Background

Except for workers exposed to formaldehyde (Rule 325.51451-.51477), there are no legal requirements to perform medical surveillance on individuals exposed to occupational allergens (View a list of common workplace allergens). The Michigan Occupational Safety and Health Administration's (MIOSHA) Respiratory Protection Standard 1910.34 (e) (1) states that the employer shall provide a medical evaluation to determine the employee’s ability to use a respirator, before the employee is fit tested or required to use the respirator in the work place.

Annual medical examinations for individuals who are potentially exposed to occupational allergens is good medical practice. It has been well documented that the longer an individual remains exposed to an occupational allergen that he/she has become sensitized to, the more likely that he/she will have persistent breathing problems even after exposure has ended (go to the bottom of this page for a listing of relevant articles from the medical literature). The purpose then of an annual medical screening is to identify symptomatic individuals and remove them from exposure so as to reduce the likelihood of causing a chronic disability.

Studies in the medical literature do not support excluding individuals with an allergic disposition (family or personal history) or cigarette smokers identified in a pre-placement physical, from working around occupational allergens. The dose that an individual inhales from both usual daily exposure and non-routine heavy exposures from spills is the best predictor of who will become symptomatic.

Accordingly, medical surveillance is NOT a substitute for good dust and chemical control in the work place. Controlling exposure is the only effective primary prevention strategy.

Protocol

1) Questionnaire – A standardized questionnaire should be administered.

A questionnaire should be administered during a pre-placement physical to obtain a baseline and on an annual basis. Since the symptoms from occupational allergens can be intermittent particularly when they first begin, the person may have a completely normal physical examination and breathing test and still be having severe attacks of asthma. Click here to find key questions that should be included at an initial and annual examination.

2) Physical examination – A physical examination with particular attention to the skin, head, eyes, ears, nose, throat, and lungs should be performed pre-placement as a baseline and on an annual basis.

3) Pulmonary function testing should be done as a baseline and annually.  All pulmonary function testing should use equipment and follow the protocol of the American Thoracic Society1.  The technician administering the test should have completed an accredited training course such as one approved by the National Institute for Occupational Safety and Health.

It is important not only to evaluate the latest pulmonary function test as to whether it is normal or abnormal, but also to observe excessive loss between successive years. Studies on isocyanate exposure have suggested excessive loss (>25-35 ml per year) as a potential adverse effect, even in the absence of symptoms of asthma.

Individuals who are suspected to have occupational asthma should have the diagnosis confirmed by pre and post shift or mid shift (depending when the individual becomes symptomatic) pulmonary function testing or measurement of peak flow every two hours over a two-week period with a portable peak flow meter. Sufficient time off work (two weeks or more) may be necessary to allow recovery and documentation by peak flow measurements.

Individuals with confirmed work-related asthma should, whenever possible, be given the option of transfer to areas of non-exposure. ; Sensitized individuals may react at extremely low levels of exposure. In order for this transfer option to be a realistic alternative, the individuals should be able to maintain his/her pay rate at the new job.

All individuals should be strongly advised to stop smoking. For exposures to some substances, smokers with similar levels of exposure as nonsmokers will develop work-related asthma at higher rates and in a shorter period of time than non-smokers.

References

1. American Thoracic Society. Standardization of Spirometry – 1994 Update. American Journal of Respiratory and Critical Care Medicine 1995; 152: 1107-1136.
2. Yassi A. Occupational Health Program, University of Manitoba, Winnipeg, Canada. Health and socioeconomic consequences of occupational respiratory allergies: a pilot study using workers' compensation data. American Journal of Industrial Medicine 1988;14(3):291-8.
View abstract on PubMed.
3. Mapp CE, Corona PC, De Marzo N, Fabbri L. Institute of Occupational Medicine, University of Padova, Italy. Persistent asthma due to isocyanates. A follow‑up study of subjects with occupational asthma due to toluene diisocyanate (TDI). American Review of Respiratory Disease 1988 Jun;137(6):1326-9.
View abstract on PubMed.
4. Malo JL, Cartier A, Ghezzo H, Lafrance M, McCants M, Lehrer SB. Department of Chest Medicine, Hopital du Sacre‑Coeur, Montreal, Canada. Patterns of improvement in spirometry, bronchial hyperresponsiveness, and specific  IgE antibody levels after cessation of exposure in occupational asthma caused by snow‑crab processing. American Review of Respiratory Disease 1988 Oct;138(4):807-12.
View abstract on PubMed.
5. Chan-Yeung M, Evaluation of impairment/disability in patients with occupational asthmaAmerican Review of Respiratory Disease 1987 Apr;135(4):950-1.

For more information or questions visit Michigan State University's Occupational & Environmental Medicine Department, or contact them by phone at (517)353-1846