Health & Environment

SAFE USE OF NICKEL IN THE WORKPLACE

Last Revised: 7/2002

6. ASSESSING THE RISKS OF WORKERS EXPOSED TO NICKEL
6.1 DETERMINING THE POPULATION AT RISK
6.2 IDENTIFYING THE HAZARDS
6.3 ASSESSING EXPOSURES AND HEALTH OUTCOMES
6.3.1 PRE-PLACEMENT ASSESSMENT
6.3.2 PERIODIC ASSESSMENT
6.3.3 BIOLOGICAL MONITORING
6.3.3.1 NICKEL IN URINE
6.3.3.2 NICKEL IN BLOOD
6.4 DEVELOPING DATA COLLECTION AND MANAGEMENT SYSTEMS
6.5 TRAINING
6.6 BENCHMARKING
6.7 REFERENCES

6. ASSESSING THE RISKS OF WORKERS EXPOSED TO NICKEL

Any efforts to evaluate occupational health risks such as those identified in Chapter 5 must start with good data collection. This includes not only monitoring workplace exposures (discussed in Chapter 7), but assessing the health of individual workers with the ultimate goal of keeping the worker healthy and reducing the overall risks in the work environment. It is not enough to periodically monitor workers, but programs must be implemented in ways that allow for the systematic collection of data that can be used in epidemiological studies and, subsequently, risk assessment. In some countries, implementation of a health surveillance program is obligatory. In such instances, any company-based surveillance program should be in compliance with the relevant local/national guidelines. Developing infrastructure and systems that support consistent data collection and storage requires effort, careful planning, and an adequate allocation of resources. It means enlisting the total commitment and cooperation of the most senior members of the management team (starting with the CEO) to the most junior constituents of the labor force. A number of specific steps have been identified as being basic to setting up a data collection system for quantitative risk assessment (Verma et al., 1996; ICME, 1999¹ ). These are discussed below, in a modified form, with particular reference to nickel where appropriate.

¹The International Council on Metals and the Environment, now known as the International Council on Mining and Metals.

6.1 DETERMINING THE POPULATION AT RISK

A worker is "at risk" if he or she has a greater chance of developing disease than a similar, but non-exposed worker (Verma et al., 1996). Using this broad based definition of an "at risk" worker, it is clear that not only production workers, but office workers and support staff may have occasion to be exposed to nickel and its compounds in various industrial settings. Consideration should also be given to contractors, such as temporary workers or long-term maintenance crews employed at factories, as some of these workers may be employed in potentially high exposure jobs. While the management and follow-up of contractors may not be the direct responsibility of a given nickel company, it may, nevertheless, be useful in some nickel operations to document contractors' exposures and maintain records. Hence, for purposes of risk assessment, records should be kept on most, if not all, workers employed in the nickel industry. Companies should assign a unique identifier to each individual. Use of last names and/or birth dates is not recommended, as such identifiers may be shared by more than one employee. Sequentially assigning numbers to workers at date of hire or devising alpha/numerical codes for each individual is preferred. Once assigned to a worker, a number should always refer to that individual only.

Identification information that should be recorded includes the employees' full name and that of his or her parents, birth date, gender, place of birth, ethnic origin, other significant dates (such as date of hire, date of departure, date of death, etc.) and other potential identifying numbers (such as social security or medical insurance numbers). Records should be periodically updated (even after employees have retired or left for other employment); they should also be well maintained and easily retrievable (Verma et al., 1996). Consideration should be given to creating coding that would be universal throughout the nickel industry so that meaningful epidemiological studies can be optimized (Hall, 2001). This would apply not only to identification data, but to any data collected as part of a health surveillance program (see below).

6.2 IDENTIFYING THE HAZARDS

A hazard can be defined as the set of inherent properties of a substance that makes it capable of causing harm to humans (Cohrssen and Covello, 1989). The likelihood of harm resulting from exposures determines the risk. As noted in Chapter 5, under certain circumstances (e.g. high exposures or prolonged contact) every nickel species may be capable of causing some type of harm². It is, therefore, very important to identify all potentially harmful substances and to monitor and control exposures in order to manage the risk.

²The nickel "species" most relevant to the workplace are metallic nickel (including elemental nickel and nickel alloys), oxidic, sulfidic, and soluble nickel compounds, and nickel carbonyl.

With respect to hazards, all the nickel species present in an industrial setting should be identified and a complete inventory of raw materials used, materials produced, by-products, and contaminants should be taken (Grosjean, 1994; Verma et al., 1996; ICME, 1999). Consideration should be given to monitoring these materials not only under normal operations, but also when short-term peak exposures occur (e.g., during maintenance). In addition, a record should be made of all procedures and equipment used (including control equipment such as local exhaust ventilation and respirators), changes in processes, and changes in feed materials. Preparing flow charts and floor plans can help to identify areas where potentially harmful substances might exist (Duffus, 1996; Verma et al., 1996; ICME, 1999).

Complementing this description of the physical plant should be a description of the workers employment history. Such a work history should include both past and present employment (Hall, 2001). A past employment history should include:

All previous workplaces.
All previous workplace exposures (both qualitative and quantitative).
Duration of all previous workplace assignments.
Nature of work performed at all previous worksites.

Present employment records should include:

Date of start of work assignments at present employment.
Duration of all work assignments at present employment.
Nature of work performed with each work assignment.
Exact location of each work assignment performed.
Details of exposure (e.g., nickel-containing substances, dusts, noise).

Measurements pertaining to the work assignment (particularly noting whether these measurements are based on static or personal sampling and how they were obtained (see Chapter 7 for further discussion).

Health surveillance/biological monitoring records where appropriate (see Section 6.3 below).

Periodic updates of exposure data and job histories should be conducted on all workers.

6.3 ASSESSING EXPOSURES AND HEALTH OUTCOMES

With respect to exposures, two types of exposure data are required: those that pertain to the ambient environment (e.g. workplace air) and those that pertain to the internal environment of the worker (e.g. health surveillance). To be of use in risk assessment, each must be linked to the other. Workplace surveillance (air monitoring) is discussed in detail in Chapter 7. Human health surveillance is discussed below.

Health surveillance may be used to evaluate an individual's health prior to, during, and at termination of employment. Occasionally, it also may be used during retirement. A properly executed health surveillance plan can be useful in determining changes in the health status of an employee. However, considerable clinical skill and judgment will be required to assess whether any change can be attributed to workplace conditions.

In countries where it is possible to obtain mortality or cancer registry data, follow-up of personnel who have left the industry is strongly recommended so that information on the eventual cause of death can be made available for possible epidemiological research. Likewise, employers are advised to retain copies of death certificates of all personnel who die while still employed or as pensioners. Special efforts to ascertain the vital status of workers who have "quit" the workforce are recommended (Verma et al., 1996).

In addition to mortality data, morbidity data may also be obtained in certain countries as part of voluntary data collection programs, such as the United Kingdom's Occupational Physicians Reporting Activity (OPRA) program, or as part of a national, state, or provincial accident/disease registry or workmen's compensation program. Such data may be useful in identifying occupational disease trends (e.g., cases of occupational asthma) within an industry sector.

The decision to commence a surveillance program has many biological, social, and legal considerations that must be taken into account. As noted in the introduction, in some countries, implementation of a health surveillance program is obligatory. In such instances, advice should be sought from the relevant local/national authority. Further legal considerations may include requirements for medical recordkeeping. In some countries, medical records are required to be kept for the duration of a worker's employment plus an additional prescribed time (usually 30 to 40 years).

Issues such as the invasiveness, sensitivity, and accuracy of testing procedures should also be considered, and any potential health benefits of these procedures should be weighed against the risks of performing such tests. Where possible, tests should be designed to investigate the quantitative relationship between the ambient workplace exposure, the biological measurement of the exposure, and the health effect of concern. The rights of workers with respect to issues such as confidentiality and compulsory examination must be carefully considered. Any health data gathered and recorded should be subject to rigorous quality control. The International Council on Mining and Metals has developed a Guide to Data Gathering Systems for the Risk Assessment of Metals (ICME, 1999). Useful information regarding the data needs of a health surveillance program is provided within this guide.

In structuring a health surveillance program, consideration ideally should be given to the components discussed below.

6.3.1 Pre-Placement Assessment

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 (notably the respiratory system and skin, but also reproductive and renal systems) that potentially might be affected by nickel and its compounds (see Chapter 5).

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, 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, possible, 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 better characterize the baseline data. 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 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.

If deemed necessary by a physician, testing for allergic nickel dermatitis 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 separately measure the amounts of soluble nickel (the ultimate allergen) from particulate and total nickel. 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 the physical demands of the job 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).

6.3.2 Periodic Assessment

The purpose of a periodic assessment is to monitor the general health of the worker at established times during the course of employment. Periodic examinations may be undertaken for three distinct purposes:

To evaluate the general health status and life-style of an employee as part of a non-specific employment package.
To assess the health status of an employee with respect to a specific industry or operation within an industry.
To provide on-going health surveillance of workers for use in epidemiological studies.

Before undertaking any such specific program, the occupational health physician should carefully consider:

The needs and objectives of the program.
The usefulness of the possible or planned procedures in indicating current disease or forecasting future significant pathological change.
The potential benefits to both the individual and the employer.
Existing legal requirements to periodically monitor workers and assure that any program implemented by a company is in compliance with local/national regulations.

At the outset, a procedure should be agreed upon by both management and the employees' representatives on the action to be taken with respect to those individuals who are found to have problems that render them unsuitable for their current work (e.g., a worker presenting with skin allergies). A single approach may not be applicable to all companies; hence, solutions may need to be tailored to meet the specific needs of a given company and its workers. Any actions taken to remedy a problem should consider the practical consequences of moving a worker, e.g., financial repercussions and job prospects, as well as potential legal constraints such as medical removal provisions of applicable occupational health regulations.

As with pre-placement examinations, plant-specific periodic assessments should examine the general health and lifestyle of a worker, as well as nickel-associated concerns. Such examinations should include a reevaluation of personal habits and recent illnesses, standardized respiratory and dermal symptom questionnaires, a physical examination, and a reevaluation of the worker's ability to use the types of respiratory equipment that may be required for particular tasks. As noted in the beginning of this Chapter, air monitoring data (discussed further in Chapter 7) needs to be linked to health surveillance data; hence, any personal dust monitoring for nickel data should be kept in the worker's medical records. Review of these records with the worker should be undertaken at the time that a periodic assessment is conducted.

X-rays and pulmonary function tests are surveillance tools of value to detect the presence of pulmonary abnormalities at a group level. Unless a risk assessment indicates otherwise, measurements of respiratory function and chest X-rays are recommended every 5 years for surveillance. Depending on the age of the workers (45 years or older), the smoking status, and the job task (nature, duration and level of dust/nickel exposure), more frequent chest X-rays may be appropriate. However, if abnormalities are detected, further tests should be carried out as appropriate, and the frequency of surveillance should be increased. It should be noted that in some countries chest X-rays may be required by law.

6.3.3 Biological Monitoring

For some metals, biological monitoring of urine, blood, and other tissues or fluids may provide a reasonable estimate of exposure which is predictive of health risks. This has not been shown to be the case for nickel (Sunderman et al., 1986). While urinary and blood nickel levels provide a reasonable estimate of recent exposure to soluble nickel compounds and nickel metal powder, they do not provide a reliable measure of exposure to other less soluble forms of nickel, nor do they truly provide a reliable measure of total body burden. Rather, they provide an integrative measure of the nickel that has been absorbed in the body from all routes of exposure (inhalation, dermal, and oral). Furthermore, with the exception of nickel carbonyl gas (see below), no consistent correlation has been found between nickel concentrations in biological media and increased health risks following exposure to either soluble or insoluble nickel compounds. Assessments of workplace exposure to inhalable aerosols are likely to better reflect health risks than consideration of nickel levels in urine or plasma (Werner et al., 1999). Hence, for the most part, the use of blood and urinary nickel concentrations are not recommended as surrogates of nickel exposure or nickel-associated health risk.

That said, biological monitoring does provide additional exposure information on an individual and group basis, and also an assessment of the effectiveness of control measures to protect the worker. It can provide reassurance to workers that control measures do work and that they are not absorbing an excessive amount of a potentially harmful substance from the workplace (White, 2001). It can also be used as an education tool for good personal hygiene. It is mainly useful in situations where exposures are to soluble nickel compounds, nickel metal powder, or nickel carbonyl. It is less useful in situations where exposures are predominantly to water insoluble compounds or where exposures are mixed.

There are three key factors to a successful biological monitoring strategy (White, 2001). They are:

Appropriate sampling-correct sample type, proper sample timing of sample collection, and avoidance of contamination.
Accuracy of measurement-use of validated methods of analysis and quality assurance procedures.
Interpretation of results-knowledge of the chemical and physical characteristics of the substance, routes of exposure and uptake, metabolism and excretion, biological limit values.

If a biological monitoring program is implemented, it should augment an environmental monitoring program, so that the biological monitoring information alone is not used as a surrogate of exposure. Both programs should be implemented in conjunction with an industrial hygiene program. In the past, health-based limits of permissible nickel concentrations in blood or urine³ of individuals or groups of workers exposed in either the using or producing industries were lacking due to a paucity of quantitative information on dose-response relationships between these parameters and nickel toxicity (Sunderman et al., 1986). However, some regulatory bodies are now attempting to set Biological Limit Values (BLVs) for nickel and nickel compounds in conjunction with Occupational Exposure Limits (OELs), despite the fact that the utility of setting BLVs for nickel have been questioned by some (Werner et al., 1999). Both OELs and BLVs are discussed in more detail in Chapter 9. It is worth noting that there are no established guidelines for how frequently one should monitor workers, although preliminary recommendations are made below.

³Some attempts have been made to look at nickel in nasal tissue as a possible indicator of nickel exposure (Torjussen et al., 1979; Boysen et al., 1982). However, due to the problems associated with the invasiveness of the biopsy technique, the use of nasal tissue monitoring is not recommended as a routine procedure (Aitio, 1984).

6.3.3.1 Nickel in Urine

Soluble nickel compounds are rapidly excreted from the body; consequently, they do not bioaccumulate (Hall, 1989). The biological half-time of soluble nickel in urine following inhalation has been reported to range from 17 to 39 hours in humans (Tossavainen et al., 1980). Reported urinary excretion of nickel following oral exposures is also quite rapid (Sunderman et al., 1989). Because of this rapid clearance of soluble nickel from the body regardless of route of exposure, levels in urine are indicative only of relatively recent exposures.

Relatively insoluble nickel, on the other hand, is known to accumulate in tissue such as lung, where, depending upon particle size, it may only slowly be absorbed over time. Nickel in urine, therefore, only reflects the fraction of insoluble nickel that has been absorbed. The smaller the particle, the more likely it is to be rapidly absorbed and excreted. This phenomenon may account for the relatively short half-times of nickel in urine-ranging from 30 to 53 hours-reported by Zober et al. (1984) and Raithel et al. (1982) for workers exposed to welding fumes and/or insoluble nickel particles of small diameter. Conversely, some have suggested that for workers presumably exposed to insoluble nickel of larger particle size, the biological half-time of stored nickel may be considerably longer, possibly ranging from months to years (Torjussen and Andersen, 1979; Boysen et al., 1984; Morgan and Rouge, 1984).

Urine samples for nickel analysis can be collected by spot sampling or by 24?hour sampling. The most sensitive method for correlating urinary nickel concentrations to air nickel concentrations is the 24?hour urine sample (Hall, 1989). A spot urinary sample tends to be more variable and, therefore, is not as informative. However, since collection of a 24?hour urine sample may be impractical in an occupational setting, post-shift or end of week spot sampling is the preferred method when 24-hour sampling cannot be carried out.

Due to variable urine dilution, spot samples are typically normalized on the basis of either creatinine concentration or specific gravity. A study of 26 electrolytic nickel refinery workers suggests that specific gravity normalization of nickel concentration is more appropriate than creatinine adjustment (Sanford et al., 1988). However, drawbacks to both methods exist, depending upon factors such as the degree of dilution of the sample, the fluctuations of salt in the body, and the presence of glycosuria or proteinuria (Lauwerys and Hoet, 1993). Some evidence exists that on a group basis, there may be no difference between corrected and uncorrected samples (Morgan and Rouge, 1984). A recent study of Scandinavian nickel workers, however, suggests that corrected urinary samples (adjusted for creatinine concentrations) correlate better with measurements of nickel aerosol than do "raw" uncorrected samples (Werner et al., 1999). A study of urinary nickel levels at a nickel refinery in Russia showed lower urinary nickel values in females than in male workers with similar inhalation exposures (Thomassen et al., 1999).

It is important that urine samples be analyzed by a reputable laboratory accustomed to doing the required analyses (Hall, 2001). It is also important that the analyses be reported in appropriate units; in the case of urine, typically as mg Ni/gm creatinine or µmol Ni/mol creatinine. If a biological monitoring program is instituted, urine nickel samples should be collected quarterly or semi-annually (Hall, 2001).

Urinary nickel levels can vary considerably, even in non-occupationally exposed individuals. Because of this, they are of most use when interpreted on a group basis. Reported urinary nickel concentrations in non-exposed individuals range from approximately 0.2 to 10 µg Ni/L (depending upon the method of analysis) (Sunderman et al., 1986; Sunderman, 1989).

As noted above, the only nickel compound for which a correlation between urinary nickel concentrations and adverse health effects has been found is nickel carbonyl. There is a close correlation between the clinical severity of acute nickel carbonyl poisoning and urinary concentrations of nickel during the initial three days after exposure (Sunderman and Sunderman, 1958). The correlations are as follows:

Mild Symptoms-60 to 100 µg Ni/l (18-hour urine specimen).
Moderate Symptoms-100 to 500 µg Ni/l (18-hour urine specimen).
Severe Symptoms-> 500 µg Ni/l (18-hour urine specimen).

These values are only relevant, however, where urinary nickel is not elevated due to other exposures.

Recent experience at a nickel carbonyl refinery from 1992-2002 has shown that the clinical severity of the acute nickel carbonyl exposure can also be correlated to nickel levels in early urinary samples (within first 12 hours of exposure). The use of an 8-hour post exposure urinary nickel specimen may also be helpful in categorizing cases and determining the need for chelation therapy. Of 170 potentially exposed cases, mild cases were defined as having <150 µg Ni/l, moderate cases had 150-500 µg Ni/l, and severe cases had >500 µg Ni/l (with 8 hours post exposure samples) (Dr. S. Williams, Inco, personal communication). Chelation therapy with disulfiram was considered on the moderate and severe groups only.

Nickel carbonyl is also the only nickel compound for which information is available regarding treatment following acute exposure. The administration of either sodium diethyldithiocarbamate (Dithiocarb) or its analogue, tetraethylthiuram disulfide (Disulfiram, which is marketed as the proprietary drug, Antabuse, and is more readily commercially available), has been recommended in the treatment of nickel carbonyl poisoning. Both agents work by chelating the metal in the blood and transporting it to the kidneys for rapid excretion in urine.

In summary, from the above discussions, it is evident that there are both advantages and disadvantages to using urinary nickel concentrations in biological monitoring programs. The disadvantages include fluctuating specific gravity, problems associated with dilute urine, matrix variability and possible dust contamination, and, with the exception of nickel carbonyl, the lack of any dose-effect relationship (Sunderman, 1989). The advantages are the non-invasiveness of the technique and convenience of collection. Also, urinary nickel concentrations are higher than concentrations in other biological media, improving sensitivity, analytical accuracy, and precision (Sunderman et al., 1986). When compared to other methods for estimating biological exposures (e.g. serum nickel), the advantages of collecting urinary nickel make it the preferred biological monitoring method.

6.3.3.2 Nickel in Blood

The half-time of nickel in serum is similar to that in urine. Values ranging from 20 to 34 hours have been reported for workers exposed to soluble nickel compounds via inhalation (Tossavainen et al., 1980). A half-time of 11 hours was observed in human volunteers orally dosed with soluble nickel sulfate hexahydrate (Christensen and Lagesson, 1981).

Just as in the case of urinary nickel, serum nickel levels cannot be used as indicators of specific health risks. They are of most use when interpreted on a group basis. Serum or plasma nickel levels can provide an indication of recent exposure to nickel metal powder or relatively soluble nickel compounds. Likewise, elevated serum or plasma nickel levels in individuals exposed solely to less soluble nickel compounds may reflect significant absorption that could be indicative of a corresponding long-term increase in workplace exposures. Normal serum or plasma nickel values in workers exposed to less soluble forms of nickel do not necessarily indicate an absence of exposure to such forms. Because serum nickel is not a good predictor of health risks, conclusions regarding the presence or absence of risk should not be drawn from such data.

Serum and plasma concentrations of nickel tend to be similar, whereas whole blood concentrations have been found to be approximately twice that of serum and plasma (Baselt, 1980). Pre- or post-shift sampling is typically performed (Sunderman et al., 1986), although in some instances, both morning and after-work samples have been taken in the same workers (Høgetveit et al., 1980). Nickel concentrations in the serum and plasma of healthy non-exposed individuals range from 0.05 to 1.1 µg Ni/L (Sunderman et al., 1986). Like urine nickel samples, it is important that blood samples be analyzed by a reputable laboratory. Analysis should be reported as mg Ni/100ml or µmol Ni/100ml. If a biological monitoring program is instituted, blood nickel samples should be collected annually (Hall, 2001).

As with urinary nickel measurements, there are both advantages and disadvantages to using serum nickel concentrations in biological monitoring programs. The primary disadvantages of measuring serum or plasma nickel levels are that the sampling technique is invasive and serum and plasma nickel levels are lower than urinary levels (Sunderman, 1989). The primary advantages are that serum and plasma samples are less subject to matrix variability fluctuations and to contamination from workplace dust.

6.4 DEVELOPING DATA COLLECTION AND MANAGEMENT SYSTEMS

An integral part of setting up a data collection system for quantitative risk assessment is selecting and/or designing an appropriate software program for database management. Given the volume of data required to assess the risks of workers (exposure data, surveillance and screening data, biological monitoring, etc.), it is imperative that some form of automated data collection system be implemented. Often the problem of assessing risks is not so much the absence of relevant data as it is its inaccessibility and lack of quality assurance in the data that exists (Lippmann, 1995). Whether the system used is a commercial one or one specifically designed by company personnel, it should embody the following features (Verma et al., 1996; ICME, 1999):

Compatibility with other computer databases in the company (e.g. payroll or health benefits).
Use of unique identifiers as the key field for all employee-based files.
Development of a centralized database that can summarize and link all individual records.
Quality assurance programs to check data quality and integrity.
Built-in mechanisms for protecting the confidentiality of employees' personal information.
Fail-safe operations (e.g. database replication) to prevent loss of information. Storage of hard copy computer records (although resource intensive) can provide an additional level of safety, assuring no loss of data (Duffus, 1996).

6.5 TRAINING

It is preferable that any implemented health surveillance program be administered by qualified occupational health specialists. The expertise of professional industrial hygienists, physicians, and technicians will likely be required. However, once a proper data collection system is in place, non-expert staff can help to collect some of the data on a day-to-day basis. This is particularly true for much of the ambient monitoring data discussed in greater detail in Chapter 7. Workers can be trained to collect data "on the job" or through short-term courses. Training should include instruction in epidemiology, basic industrial hygiene, air sampling, and toxicology/health effects (Verma et al., 1996). Good communication and teaching skills will be required of employees helping to administer health and workplace surveillance programs. Distance education courses are offered by several research centers and universities so that personnel from small companies or more remote locations need not be prohibited from acquiring the necessary skills required to collect useful data for risk assessment purposes. Sources for training personnel are provided in the aforementioned Guide to Data Gathering Systems for the Risk Assessment of Metals (ICME, 1999).

6.6 BENCHMARKING

It is important that any surveillance program implemented be evaluated to know how well it is working. This is an often overlooked feature of data collection. A data gathering system is not a static system. Improved technology, altered plant processes, and changes in staff can all affect the type and way that data are collected (ICME, 1999). Benchmarking provides a means to integrate such changes and to improve the efficiency of established programs. It is simple in concept, requiring the assessment of the strengths and weaknesses of any data gathering system within a company and acting to implement changes where and when weaknesses are identified.

Evaluations made should be both top-down and bottom-up. It is not enough for management, alone, to evaluate the effectiveness of a program. The opinions and suggestions of workers on how to improve health and workplace surveillance programs should also be sought. Data gaps need to be identified. Goals need to be set against which future evaluations can be made. Action plans for making changes to any processes found wanting need to be drafted. Feasibility, including financial and staff resources, needs to be considered.

In summary, it is important not only to gather data, but to use the data in a way that identifies and reduces the risks of occupational exposures in the workplace so that they are acceptable from a health, safety, and environmental perspective.

6.7 REFERENCES

Aitio, A. (1984). Biological monitoring of occupational exposure to nickel. In: Sunderman, F. W., Jr., et al., eds. Nickel in the Human Environment: Proceedings of a Joint Symposium, March 1983, Lyon, France. Lyon, France: International Agency for Research on Cancer. (IARC Scientific Publication No. 53). pp. 497-505.

Baselt, R. (1980). Biological Monitoring Methods for Industrial Chemicals. Davis, California: Biomedical Publications. pp. 193-196.

Boysen, M., Solberg, L. A., Andersen, I., Høgetveit, A. C., Torjussen, W. (1982). Nasal histology and nickel concentration in plasma and urine after improvements in the work environments at a nickel refinery in Norway. Scand. J. Work Environ. Health 8: 283-289.

Boysen, M, Solberg, L. A., Torjussen, W., Poppe, S., Høgetveit, A. C. (1984). Histological changes, rhinoscopical findings and nickel concentrations in plasma and urine in retired nickel workers. Acta Otolaryngol 97: 105-115.

Christensen, O. B., Lagesson, V. (1981). Nickel concentration of blood and urine after oral administration. Ann. Clin. Lab. Sci. 11: 119-125.

Cohrssen, J.J., Covello, V.T. (1989). Risk Analysis: A Guide to Principles and Methods for Analyzing Health and Environmental Risks. National Technical Information Services, Springfield, VA. NTIS Order No. PB 89-137772.

Duffus, J.H. (1996). Epidemiology and the indentification of metals as human carcinogens. Sci. Prog. 79(4): 311-326.

Fischer, T. (1989). Occupational nickel dermatitis. In: Maibach, H. I., Menné, T., eds. Nickel and the Skin: Immunology and Toxicology. Boca Raton, Florida: CRC Press. pp. 117-132.

Gawkrodger, D.J. (2001). Biological monitoring program for nickel-exposed workers: dermatological aspects. Proceedings of a Workshop: Occupational Exposure and Health Assessment Guidelines for Nickel. Nickel Producers Environmental Research Association (NiPERA), April, 2001, London, U.K. CD ROM available through NiPERA, Durham, NC.

Grosjean, M. (1994). European standardization: guidance on the assessment of occupational exposure to chemical agents. Analyst 119: 9-12.

Hall, S. K. (1989). Biological monitoring of metal exposure. Pollut. Eng. 1: 128-131.

Hall, G.W. (2001). Occupational health aspects of lung cancer and monitoring of the workplace and the worker in nickel exposures. Proceedings of a Workshop: Occupational Exposure and Health Assessment Guidelines for Nickel. Nickel Producers Environmental Research Association (NiPERA), April, 2001, London, U.K. CD ROM available through NiPERA, Durham, NC.

Høgetveit, A. C., Barton, R. T., Andersen, I. (1980). Variations of nickel in plasma and urine during the work period. J. Occup. Med. 22: 597-600.

ICME. International Council on Metals and the Environment. (1999). Guide to Data Gathering Systems for Risk Assessment of Metals and Metal Compounds. Ottawa, Ontario, Canada. Available through the International Council on Mining and Metals, London, UK.

Lammintausta, K., Maibach, H. I. (1989). Clinical concepts in nickel testing. In: Maibach, H. I. and Menné, T., eds. Nickel and the Skin: Immunology and Toxicology. Boca Raton, Florida: CRC Press. pp. 91-99.

Lauwerys, R. R., Hoet, P. (1993). Biological monitoring of exposure to inorganic and organometallic substances: Nickel. Industrial chemical exposure: Guidelines for biological monitoring. 2nd ed. Boca Raton, FL: Lewis Publishers. pp. 82-85.

Lippmann, M. (1995). Exposure data needs in risk assessment and risk management: database information needs. Appl. Occup. Environ. Hyg. 10(4): 244-250.

McMillan, C., Burrows, D. (1989). in vitro testing in nickel contact hypersensitivity. In: Maibach, H. I. and Menné, T., eds. Nickel and the Skin: Immunology and Toxicology. Boca Raton, Florida: CRC Press. pp. 79-90.

Morgan, L. G. and Rouge, P. J. C. (1984). Biological monitoring in nickel refinery workers. In: Sunderman, F. W., Jr., et al., eds. Nickel in the Human Environment: Proceedings of a Joint Symposium, March 1983, Lyon, France. Lyon, France: International Agency for Research on Cancer. (IARC Scientific Publication No. 53). pp. 507?520.

Raithel, H. J., Schaller, K. H., Mohrmann, W., Mayer, P., Henkels, U. (1982). Untersuchungen zur Ausscheidungskinetik von Nicekl bei Beschaftigten in der Glas-und Galvanischen Industrie [Study of elimination kinetics of nickel during injury in the glass and electroplating industry]. In: Fliedner, T. M., ed. Bericht über die 22. Jahrestagung der Deutschen Gesellschaft für Arbeitsmedizin [Report on the 22nd Anniversary of the German Society of Occupational Medicine]. Stuttgart, Gentner. pp. 223-228.

Sanford, W.E., Nieboer, E., Bach, P., Stace, N., Gregg, N., Dobrota, M. (1988). The renal clearance and toxicity of nickel. In; Fourth International Conference of Nickel Metabolism and Toxicology. Espoo, Finland, p. 17.

Sunderman, F. W., Jr. (1989). Chemistry, analysis, and monitoring. In: Maibach, H. I. and Menné, T., eds. Nickel and the Skin: Immunology and Toxicology. Boca Raton, Florida: CRC Press. pp. 1-9.

Sunderman, F. W., Sunderman, F. W., Jr. (1958). Nickel poisoning: VIII. Dithiocarb: A new therapeutic agent for persons exposed to nickel carbonyl. Am. J. Med. Sci., 236, 26-31.

Sunderman, F. W., Jr., Aitio, A., Morgan, L. O., Norseth, T. (1986). Biological monitoring of nickel. Tox. Ind. Health. 2(1): 17-78.

Sunderman, F . W., Jr., Hopfer, S. M., Swenney, K. R., Marcus, A. H., Most, B. M., Creason, J. (1989). Nickel absorption and kinetics in human volunteers. Proc. Soc. Exp. Biol. Med. 191: 5-11.

Thomassen, Y., Nieboer, E., Ellingsen, D., Hetland, S., Norseth, T., Odland, J., Romanova, N., Chernova, S., Tchachtchine, V. (1999). Characterization of workers' exposure in a Russian nickel refinery. J. Environ. Mon. 1: 15-22.

Torjussen, W., Andersen, J. (1979). Nickel concentrations in nasal mucosa, plasma, and urine in active and retired nickel workers. Ann. Clin. Lab. Sci. 9: 289-298.

Torjussen, W., Solberg, L. A., Høgetveit, A. C. (1979). Histopathologic changes of nasal mucosa in nickel workers: A pilot study. Cancer 44: 963-974.

Tossavainen, A., Nurminen, M., Mutanen, P., Tola, S. (1980). Application of mathematical modeling for assessing the biological half-times of chromium and nickel in field studies. Br. J. Ind. Med. 37: 285-291.

Verma, D.K., Julian, J.A., Muir, D.C.F. (1996). Infrastructure and systems for risk assessment and metal compounds on human health. Available through the International Council on Mining and Metals, London, UK.

Werner, M.A, Thomassen, Y., Hetland, S., Norseth, T., Berge, S.R., Vincent, J.H. (1999). Correlation of urinary nickel excretion with observed "total" and inhalable aerosol exposures of nickel refinery workers. J. Environ. Monit. 1: 557-562.

White, M. (2001). Biological monitoring for workplace exposures to nickel and nickel compounds. Proceedings of a Workshop: Occupational Exposure and Health Assessment Guidelines for Nickel. Nickel Producers Environmental Research Association (NiPERA), April, 2001, London, U.K. CD ROM available through NiPERA, Durham, NC.

Zober, A., Weltle, D., Schaller, K. H. (1984). Untersuchungen zur Kinetik von Chrom and Nickel in biologischen Material wahrend einworchigen Lichtbogenschweissens mit Chrom-Nickel-Haltigen Zusatzwerkstoffen [Study of the kinetics of chromium and nickel in biological material during a week of arc welding using chromium-nickel-containing filler metals]. Schweissen Schneiden. 10: 461-464.

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