Health, safety, and productivity in a manufacturing environment.

The Health and Productivity Management model at International Truck and Engine Corporation includes the measurement, analysis, and management of the individual component programs affecting employee safety, health, and productivity. The key to the success of the program was the iterative approach used to identify the opportunities, develop interventions, and achieve targets through continuous measurement and management. In addition, the integration of multiple disciplines and the overall emphasis on employee productivity and its cost are key foci of the International Model. The program was instituted after economic and clinical services' analyses of data on International employees showed significant excess costs and a high potential for health care cost reductions based on several modifiable health risk factors. The company also faced significant challenges in the safety, workers' compensation, and disability areas. The program includes safety, workers' compensation, short-term disability, long-term disability, health care, and absenteeism. Monthly reports/analyses are sent to senior management, and annual goals are set with the board of directors. Economic impact has been documented in the categories after intervention. For example, a comprehensive corporate wellness effort has had a significant impact in terms of reducing both direct health care cost and improving productivity, measured as absenteeism. Workers' compensation and disability program interventions have had an impact on current costs, resulting in a significant reduction of financial liability. In the final phase of the program, all direct and indirect productivity costs will be quantified. The impact of the coordinated program on costs associated with employee health will be analyzed initially and compared with a "silo" approach.

The scope of international occupational medical practice.

The international physician has a tremendous scope of responsibility. Clinical care and its management, occupational and environmental medicine, travel medicine, marine and aviation medicine, public health and other disciplines must be addressed. Programmes must include expatriates, national citizens, travellers, families, extended families, and the surrounding communities. Moreover, in the international context, the occupational physician is a representative of the company in the host country. Furthermore, the knowledge required is not only vast, but changes rapidly. It requires not only clinical acumen, but also the ability to effectively design and implement many types of programmes in the context of the customs and regulations of the country and with the guidance of management.

Occupational exposure to inorganic mercury vapour and reproductive outcomes.

The effect of exposure to inorganic mercury on the pregnant woman and her foetus has received little attention. Transport of elemental inorganic mercury into foetal tissues has been reported, and prior studies indicate a higher incidence of adverse pregnancy outcome. The effects of occupational exposure to inorganic mercury on pregnancy were investigated among 46 exposed women workers: controls were 19 women working in non-production areas of the same factory. There were 104 recorded total pregnancies during the period 1948-77. The study revealed a higher frequency of adverse reproductive outcomes, especially congenital anomalies, among the women exposed to inorganic mercury levels at or substantially lower than 0.6 mg/m3; no significant differences in the stillbirth or miscarriage rates were noted between the two groups of women. The overall foetal death rate in this study was similar to New York state (USA) and national levels for the same period.

Longitudinal changes in lung function among asbestos-exposed workers.

To prospectively identify the determinants of persistent or accelerated loss of lung function among workers occupationally exposed to asbestos and assess the relative contribution of cigarette smoking, asbestos-induced pleural fibrosis, and specific findings from bronchoalveolar lavage and high resolution CT scans, we examined the determinants of lung function changes in 117 subjects occupationally exposed to asbestos for at least 1 yr in a high exposure setting. A minimum of 20 yr was required between the first exposure to asbestos and entry into the study. Baseline studies included an independent assessment of dyspnea, lung volumes, diffusing capacity of carbon monoxide (DLCO), a chest radiograph, a high resolution CT (HRCT) scan, and bronchoalveolar lavage (BAL). Subjects were observed for an average of 2 yr (range, 0.5 to 4.0 yr), and lung function was measured on at least two separate occasions (mean, 4.1 separate tests). During the period of observation, there was an average 1.5% decrease in the TLC and a 2.5% decrease in the DLCO. In this longitudinal data set, after controlling for age, height, pack-years of cigarette smoking, and follow-up time, persistently lower measures of TLC were independently related to moderate to severe dyspnea (p = 0.005), diffuse pleural thickening (p = 0.007), and higher concentrations of fibronectin in BAL fluid (p = 0.01). Interstitial lung disease either on the chest radiograph or HRCT scan was not independently associated with persistently lower measures of TLC during the period of observation. However, none of the clinical variables we examined were associated with an accelerated decline in TLC.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent studies of man-made vitreous fibers. Chronic animal inhalation studies.

The history of asbestos use and asbestos-related disease is replete with comments that the public health would have been better protected if the results of laboratory investigation, epidemiologic surveys, and clinical studies were made available at appropriate intervals during the ongoing research, rather than in the generally accepted method of awaiting completion of studies prior to reporting medical and scientific findings. No substantive evidence of long-term adverse effects has been published in workers exposed to man-made vitreous fibers. Nevertheless, in an effort to preclude a repetition of this error of omission that occurred with asbestos exposure and use, the Thermal Insulation Manufacturers Association is regularly reporting interim and final data from ongoing animal studies. A significant segment of man-made vitreous fibers have now been tested in state-of-the-art chronic studies. This paper includes the recently completed animal inhalation studies on refractory ceramic fibers and fibrous glass. It also reviews interim data on mineral wool studies.

Approaches to evaluating the toxicity and carcinogenicity of man-made fibers: summary of a workshop held November 11-13, 1991, Durham, North Carolina.

The Workshop on Approaches to Evaluating the Toxicity and Carcinogenicity of Man-Made Fibers (MMF) was held in Durham, North Carolina, on November 11-13, 1991. The goal of the workshop was to reach a consensus, or to determine the extent to which a consensus existed, in two areas. Participants were asked to identify scientifically sound approaches for evaluating the toxicity and carcinogenicity of man-made fibers based on today's science and to determine research appropriate for study during the next 5 years that can provide an improved scientific basis for future revisions of approaches used to evaluate man-made fiber toxicity and carcinogenicity. During the first day, a series of "state of knowledge" presentations were made to provide all participants with a common data base from which to interact and discuss scientific issues. The workshop participants were assigned to one of four discussion groups, which met separately in three half-day sessions following the first day of presentations. All groups discussed the same topics: exposure assessment, hazard identification, and dose-response information needed to integrate to characterize risk in the first session; approaches to obtaining the needed information in the second session; and recommended approaches and guidelines for evaluating the toxicity and carcinogenicity of MMF and research needs in the third session. The workshop participants reconvened as a whole after each discussion session, and one member from each group reported the group's conclusions. A closure period was also included at the end of the workshop for review and discussion of items that had been considered during the workshop. The primary conclusions reached were the following: -All fiber types capable of depositing in the thorax are not alike in their pathogenic potential. -Only fiber samples with dimensions similar to those to which humans can inhale should be tested. -A complete characterization (i.e., dimensions, fiber number, mass, and aerodynamic diameter) of the fiber aerosol and retained dose is essential. -Appropriate aerosol generation methods must be used for inhalation studies in order to preserve fiber lengths. -A tiered approach to toxicity evaluation is recommended that includes: 1. In vitro screening for durability, surface properties, cytotoxicity, and similar properties, etc; 2. Short-term inhalation or other in vivo studies; 3. That chronic inhalation studies are the "gold standard" (i.e., provide most appropriate data for risk characterization). -The rat is the most appropriate species for inhalation studies. -In chronic inhalation studies, animals should be retained to at least 20% survival after 2-year exposure. -Serial lung burden analyses are an essential component of inhalation studies and are essential for understanding exposure-dose-response relationships. -Studies oriented to understanding mechanisms of toxicity and carcinogenicity are important adjuncts to traditional toxicity studies. -Histopathological analyses of tissues of the respiratory tract represent primary endpoints for evaluating effects of inhaled fibers. Major effects include pulmonary fibrosis, lung tumors, and mesotheliomas. Experimental tissues should be archived for future studies; wherever possible, handling and preservation of tissues should be done in a way that maximizes their future use in mechanistic studies. -Potential human exposures throughout the entire life-cycle of the fiber must be considered and fibrous material for toxicologic studies prepared accordingly. -Intracavity studies are inappropriate for risk characterization but can play a useful screening role in assessing fiber toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulmonary toxicity of inhaled polypropylene fibers in rats.

This study was initiated to assess the pulmonary toxicity of a polyolefin fiber composed of polypropylene in male Fischer 344 rats after 90 days of inhalation exposure. To increase fiber respirability in the rodent, polypropylene fibers were size-selected before aerosolization to have a geometric mean diameter of 1.6 microns (46% < 1 micron) and a geometric mean length of 30.3 microns. Three groups of animals were exposed in nose-only inhalation chambers, 6 hr/day, 5 days/week, for 90 days to 15, 30, or 60 mg/m3 of polypropylene, or filtered air (negative control). Microscopic examination of the polypropylene fiber-exposed lungs revealed that, at all time points examined in the study, there was a dose-dependent increase in pulmonary macrophages. These minimal or mild increases in cellularity appeared to be reversible, especially at the lower doses 30 days post exposure. No fibrosis was observed in any of the groups. A strong correlation was found between the external exposure concentration, the time of exposure, and the lung fiber burden. The number of partially degraded (segmented) fibers within the lung increased with the exposure concentration and period of exposure, as well as with the period of recovery after termination of exposure at 90 days. Fibers were recovered from exposed lungs using a hypochlorite digestion technique.

Cytotoxicity of refractory ceramic fibres to Chinese hamster ovary cells in culture.

The toxicity/oncogenicity of refractory ceramic fibres have been tested in chronic inhalation studies in rodents. Because these studies are time consuming and expensive, there is a need to develop and validate short-term models to screen fibres for their toxicological potential. In the present study, the toxic effects of four different compositions of refractory ceramic fibres were determined using Chinese hamster ovary cells grown in culture. These refractory ceramic fibres were the same size-selected fibres that had been used in animal inhalation studies, thus facilitating a direct comparison of findings in the two systems. Chinese hamster ovary cells were treated with refractory ceramic fibres 24 hr after seeding into 60-mm culture dishes in Ham's F12 medium with 10% serum. Inhibition of cell proliferation and colony formation were determined after 3-5 days of fibre exposure. Crocidolite and chrysotile asbestos were used as positive controls. Concentration-dependent inhibition of both cell proliferation and colony formation was observed after treatment with refractory ceramic fibres. The LC(50) for the different refractory ceramic fibres ranged from 10 to 30 mug/cm(2). The LC(50)s for crocidolite and chrysotile were 5 mug/cm(2) and 1 mug/cm(2), respectively. To assess the genotoxic potential of these fibres, fibre-exposed Chinese hamster ovary cell cultures were stained with acridine orange and scored for the incidence of micronuclei and other nuclear abnormalities. The incidence of nuclear abnormalities for refractory ceramic fibres at 20 mug/cm(2) ranged from 20 to 40%. Toxic endpoints of the in vitro studies were compared with those of the chronic animal inhalation studies. The latter included induction of lung fibrosis and pleural and airway tumours. A correlation was observed between the in vitro and in vivo toxicological potencies of the respective four refractory ceramic fibres: the fibres that were most toxic in vitro were also the most toxic in the chronic animal inhalation studies. A direct relationship was also observed, both in vitro and in vivo, between average fibre length and the severity of the toxic effect.

Adult respiratory distress syndrome from sulfuric acid fume inhalation.

A 23-year-old man had adult respiratory distress syndrome (ARDS) caused by acute exposure to sulfuric acid fumes. The patient survived the initial hospitalization to be readmitted later with a lung abscess. After therapy, his chest roentgenogram and pulmonary function tests revealed no abnormalities except a marginally decreased DLCO, and he was without functional deficit. Noncardiogenic pulmonary edema probably resulted from direct alveolar injury caused by sulfuric acid.

Mercury exposure in chloralkali plants.

The employees of two chloralkali plants were studied to correlate the signs and symptoms of mercury toxicity with levels of exposure. For purposes of comparison, the workers were divided into three groups. These groups were selected on the basis of hours worked in the mercury cell room or in other areas of mercury exposure. The population of the first plant was studied from 1957-1978, and preliminary findings were published in 1964. The second plant's population was studied for 3.5 years beginning in 1976. Time-weighted average exposure levels to mercury vapor in the high exposure group generally ranged between 0.05 to 0.10 mg/m3. No significant differences in the frequency of objective or subjective findings were noted among the three groups except for a lower post exposure systolic and post exposure diastolic blood pressure in the high exposure group in the second plant's population. There was no correlation of mercury vapor exposure with subjective or objective weight loss.