The purpose of any pre-placement examination is to fit the worker to the job and the job to the worker. The objective is to identify any pre-existing medical conditions that may be of importance in hiring and job-placement-either at the time of hire or in the instance of a job transfer- while taking care to consider local laws regarding discriminatory practices. This examination can also provide baseline data that can be used to measure functional, pathological, or physiological changes in workers over time, thus, facilitating future epidemiological studies related to heath effects. Of particular importance is the identification of pre-existing medical conditions in target organs that potentially might be affected by nickel and its compounds (notably the respiratory system and skin, but also reproductive and renal systems).
Procedures for pre-placement health examinations are well defined but may in practice vary from country to country and between industries and occupations. However, a pre-placement examination for nickel workers should ideally include:
- Baseline health data such as height, weight, and vital statistics.
- A detailed history of previous diseases and occupational exposures (see above). The focus should be on previous lung problems and previous or present exposure to lung toxins such as silica, asbestos, irritant gases, etc.
- A history of personal hobbies or activities that might involve exposures to potential toxicants, particularly those that might affect target organs of concern to nickel species (e.g., furniture restoration in the case of the lung and possibly the skin, or woodworking in the case of nasal cancers).
- Past or present history of any allergies (particularly to nickel), including asthma.
- Identification of personal habits (smoking, hygiene, alcohol consumption, fingernail biting) that may be relevant to work with nickel, its compounds, and alloys. Histories should be sufficiently detailed. For example, for smoking, the type of smoking, duration, amount smoked, and age of onset of smoking should be recorded. Any exposure to second hand smoke should be noted.
- Complete physical examination with special attention to respiratory, dermal, and, possibly, renal problems. Validated dermal and respiratory questionnaires should be included. Renal function may need to be checked as the kidneys are the main route of excretion of absorbed nickel.
- Specific to women, reproductive questionnaires and/or examinations with special emphasis on pregnant or lactating female workers who may potentially be exposed to nickel carbonyl and or soluble nickel compounds.
- Evaluation of the individual to determine the appropriate respiratory equipment (if any) that may be worn.
In addition to the items listed above, there are a number of clinical tests that may be performed to characterize the baseline data more efficiently. These include:
- posterior/anterior chest X-ray,
- lung function tests using classical spirometry (e.g., FVC, FEV1.0),
- audiometric testing, and
- vision testing.
With respect to the latter two pre-placement tests, audiometric and visual acuity tests are commonplace where noise levels in certain facilities are high and where good vision is especially important. Reliability and accuracy are essential for the above tests to be useful. The chest X-ray should be done by a quality facility and the films themselves interpreted by a radiologist certified as a “B reader” according to the International Labour Organization. The pulmonary function tests should be administered by a certified technician who is competent in instructing individuals through the test procedure and in recognizing poor test performance (Hall, 2001).
It should be noted that none of these tests are specific to the nickel industry and that the necessity for conducting them may be job-dependent. For example, it may be important to establish the lung function of an applicant who has previously been exposed to high dust levels or for whom current job placement might involve production areas. Conversely, lung function and audiometric testing may not be necessary where employees are working in relatively non-dusty or quiet environments (e.g., administrative offices).
Skin patch testing is not recommended as a routine pre-employment procedure because there is a possibility that such tests may sensitize the applicant. However, in special circumstances, such testing may be warranted for purposes of clinical diagnosis. In view of the danger of sensitization and the difficulty in interpreting test results, patch testing should only be undertaken by persons experienced in the use of the technique.
Testing for allergic nickel dermatitis, if deemed necessary by a physician, usually involves patch testing with either 2.5 or 5 percent nickel sulfate in petrolatum; however, there is some evidence that other vehicles, such as water, dimethylsulfoxide, and softisan may prove more sensitive (Lammintausta and Maibach, 1989). It should be noted that patch tests may be ambiguous with respect to characterizing a pre-existing sensitivity versus a primary irritation. Because of this, various in vitro tests have been proposed as alternatives to patch testing, including the lymphocyte transformation test (LTT) (McMillan and Burrows, 1989; Lammintausta and Maibach, 1989). However, as these tests have not been completely validated as yet, they are not recommended for use by the nickel industry at this time. A number of sampling protocols for dermal contamination studies have been advocated, but standardization remains a problem (Gawkrodger, 2001). Methods are needed to be able to measure the amounts of soluble nickel (the ultimate allergen) from particulate and total nickel separately. Currently, the most practical methods for collecting nickel from workers’ skin and work surfaces are forensic tape and wet pads (Gawkrodger, 2001).
With respect to biological monitoring, it should be noted from the outset that any biological monitoring program, while useful in some situations, may be of limited utility in others (see Section 6.3.3). Nevertheless, should a facility decide to undertake a biological monitoring program, it might be useful to establish baseline nickel concentrations in urine and/or serum as part of the pre-placement program (see Section 6.3.3 for further details on sampling).
In conclusion, it should be stressed that plant physicians will have to establish their own criteria on which to accept or reject an applicant for job placement depending upon the requirements of the job and the applicant’s suitability. Careful consideration must be given to local laws regarding discriminatory practices. Special consideration should be given to the placement of personnel with past or present contact dermatitis or respiratory disease (especially asthma) in jobs where physical demands may be high, where there is a risk of significant nickel exposure, or where respiratory protection may have to be worn. In the case of applicants with past histories of nickel allergy, care should be taken to find suitable employment where contact with nickel- containing items will neither be direct nor prolonged and the risks of promoting a recurrence are negligible (Fischer, 1989).