Atherogenicity and carcinogenicity of high-arsenic artesian well water. Multiple risk factors and related malignant neoplasms of blackfoot disease

The objective of this study was to examine multiple risk factors and correlated malignant neoplasms of blackfoot disease (BFD), a unique peripheral vascular disease related to continuous exposure to high-arsenic artesian well water. A total of 241 BFD cases, including 169 with spontaneous or surgical amputations of affected extremities, and 759 age-sex-residence-matched healthy community controls were studied to explore the risk factors of BFD. Multiple logistic regression analysis showed that artesian well water consumption, arsenic poisoning, familial history of BFD, and undernourishment were significantly associated with the development of BFD. The life-table method used to analyze cancer mortality of 789 BFD patients followed for 15 years showed a significantly higher mortality from cardiovascular diseases, peripheral vascular diseases, and cancers of bladder, skin, lung, and liver among BFD patients as compared with the general population in Taiwan or residents in the BFD-endemic area. The results imply the atherogenicity and carcinogenicity of the artesian well water in the BFD-endemic area.

Occupational asthma due to toluene diisocyanate among velcro-like tape manufacturers

During September-November, 1985, four employees of a factory were seen at the occupational clinic complaining of cough, shortness of breath, and wheezing. All four worked in the same area of the factory where an adhesive containing toluene diisocyanate (TDI) was applied to velcro-like tape during manufacturing. To confirm the diagnosis of TDI-induced asthma and determine the prevalence among workers, 38 workers were interviewed and examined (84%) in the factory. Air samples were also taken from several areas in the factory to determine the TDI concentration. For analysis, the factory was divided into three areas based on the concentration of TDI: low (0.012 +/- 0.002 ppm), medium (0.021 +/- 0.006 ppm), and high (0.047 +/- 0.054 ppm). The distribution of workers with symptoms of asthmatic bronchitis was highly associated with TDI concentration (p less than 0.001). After stopping work for a period of 10 days, workers in areas with a high concentration of TDI showed marked improvement in pulmonary function tests (PFTs). After isolation of the exposure site, improvement of the ventilation system, and substitution of the TDI with less volatile diphenylmethane diisocyanate (MDI), air concentration of isocyanates was usually below 0.007 ppm. Three of the four clinically overt asthma cases went back to work without any difficulty. The PFTs of affected workers showed a significant improvement 5 months later. We conclude that TDI was responsible for the occupational asthma among velcro-like tape manufacturers and that the TDI-induced impairment of pulmonary functions was at least partially reversible.

Occupational risk and the development of premalignant skin lesions among paraquat manufacturers

The objective of this study was to determine the prevalence rate and possible aetiological factors of premalignant skin lesions observed among paraquat manufacturers. A total of 228 workers in 28 factories were interviewed and independently examined by a dermatologist during site inspection in 1985. Information concerning past working experience, current toxic exposures, other risk factors of hyperpigmented macules and keratosis, and the past and present manufacturing processes of each factory was collected. Sixty nine cases of hyperpigmented macules and 17 of hyperkeratosis were found. Typical macules were irregular in shape, pin head size, hyperpigmented, with or without hyperkeratosis, and usually distributed symmetrically over the forearms, hands, neck, and upper chest, where exposure to sunlight was maximal. Six patients with hyperkeratotic lesions subsequently had biopsies performed and two showed Bowenoid changes. Eighty per cent (28 cases) and 67% (38 cases) of workers developed hyperpigmented macules if they had ever been engaged in bipyridine centrifugation and crystallisation, respectively; there were three workers 3% with such lesions among those who performed packaging or administrative jobs, or both. There was a significant trend (p less than 0.0001) for workers to develop hyperpigmented macules and hyperkeratosis the longer they had been exposed to centrifugation or crystallisation, or both, independent of age and the duration of exposure to sunlight. Evidence is presented to suggest that sunlight is a necessary cofactor and that the aetiological agent was produced during high temperature sodium process of bipyridine synthesis, and possibly bipyridine isomer(s).

Direct determination of vanillylmandelic acid in human urine by reversed-phase HPLC

A reversed-phase HPLC method for the determination of epinephrine, norepinephrine, dopamine, and vanillylmandelic acid (VMA) has been developed. The concentration of VMA in the urine of hypertensive patients was measured by direct injection after centrifugation. The method is useful for the diagnosis of pheochromocytoma.

Outbreak of carbon tetrachloride poisoning in a color printing factory related to the use of isopropyl alcohol and an air conditioning system in Taiwan

Three workers from a color printing factory were admitted to community hospitals in 1985 with manifestations of acute hepatitis. One of the three had superimposed acute renal failure and pulmonary edema. An investigation was subsequently conducted at the plant to determine the etiology of the outbreak and the prevalence of liver disease among the remaining workers. Comprehensive medical evaluations were conducted, which included physical examinations, liver function tests, and serological screening for hepatitis. Seventeen of 25 workers from the plant had abnormal liver function tests 10 days after the outbreak, and a significant association was found between the presence of abnormal liver function tests and a history of recently having worked inside any of three rooms in which an interconnecting air conditioning system had been installed to cool the printing machines. After further investigation, it was determined that the incident occurred following inadvertent use of carbon tetrachloride to clean a pump in the printing machine. A simulation of the pump cleaning operation revealed ambient air levels of carbon tetrachloride of 300-500 ppm. Ultimately, it was concluded that the outbreak was in all likelihood due to the combined use of carbon tetrachloride and isopropyl alcohol in the cleaning operation. This outbreak underscores the importance of adopting appropriate industrial hygiene measures in a rapidly industrializing nation such as Taiwan.

Prevalence of probable kerosene dermatoses among ball-bearing factory workers

The objective of this study was to investigate the prevalence rate of dermatoses among workers in a ball-bearing factory and its possible association with their exposure to kerosene. Two groups of female workers participated in the study. The first group included 79 persons with major kerosene exposure during work, while the second, a reference group, was composed of 263 zipper-manufacturing workers with a similar age distribution, educational background, and income. Dermatologic examinations were used to determine the prevalence rate of hand dermatoses (erythema, scaling, and eczema). In the exposed group 51 persons (65%) had erythema with or without desquamation over the interdigital spaces, 12 persons (15%) had eczematous lesions, 3 persons (4%) had defatting dermatitis, and only 13 persons (16%) were apparently asymptomatic. In the reference group only one person had hand eczema (less than 1%). The difference in the occurrence of dermatoses between the two groups was significant according to the Mantel-Haenszel summary chi-square test. Patch tests on five workers with eczematous lesions revealed one to be sensitive to mercury. The findings indicate that kerosene is a skin irritant. Antirust oil used on the ball-bearings may also contribute to the irritant effect.

The infrahyoid myocutaneous flap for reconstruction after resection of head and neck cancer

From May 1979 to August 1984, 112 infrahyoid myocutaneous flaps (IHMCFs) were used for reconstruction of the tongue after resection of lingual carcinoma (67 flaps in 63 consecutive cases) and for repair of defects after resection of carcinomas of buccal mucosa (23 cases), floor of mouth (8 cases), parotid gland (7 cases), and other malignancies (7 cases). Ten IHMCFs were extended to Ludwig's angle for repairing the open defect of the cheek or combined defect in the buccal mucosa and hard palate. The donor sites of 76 IHMCFs could be sutured primarily. The flap was successful in 90% of the cases (101 of 112 cases). Postoperatively, 94% of the cases (60 of 64 cases) of reconstructed tongue had good deglutition and 78% of the cases (50 of 64 cases) gave satisfactory enunciation. IHMCF is a new, versatile, reliable, and convenient flap suitable for repairing the defects in and around the oral cavity, particularly in the tongue, even in aged and weak patients.

An outbreak of N-hexane induced polyneuropathy among press proofing workers in Taipei

The objective of this study was to determine the prevalence and the etiology of polyneuropathy observed among press proofing workers in Taipei. Neurological examinations of 59 workers, from 16 press proofing factories, were conducted. Fifty-four of those workers subsequently underwent studies of nerve conduction velocities. Samples of bulk solvent from the involved factories were analyzed for their contents using gas chromatography. Fifteen (25%) of the study group were found to have polyneuropathy. All 15 patients with polyneuropathy were from factories in which solvents containing n-hexane were regularly used, and there was a significant association between n-hexane concentration in the bulk samples and prevalence of polyneuropathy. The air concentration of n-hexane in one factory in which all six employees developed polyneuropathy was 190 ppm. Workers who were exposed to n-hexane at air levels of less than 100 ppm but who frequently worked overtime showed a significant slowing of motor nerve conduction velocities on median, ulnar, and peroneal nerves. Of 13 workers who regularly slept in the factory, 12 (92%) had polyneuropathy compared to three (7%) of 46 workers who did not sleep in the factory. The outbreak of polyneuropathy was attributed to a combination of the use of solvents with high contents of n-hexane, poor ventilation, and the practice of sleeping in the factories between shifts.

The mortality odds ratio (MOR) in occupational mortality studies--selection of reference occupation(s) and reference cause(s) of death

In occupational mortality studies, the information on the population at risk is frequently not available. In these circumstances, the rate ratio of interest can be assessed through the mortality odds ratio (MOR), given appropriate selections of reference occupation(s) and reference disease(s). The reference occupation should be chosen with a view to three aspects of validity: (1) comparability of effects, i.e., identity of mortality effects between the index and the reference occupation apart from the effect of the exposure under study; (2) comparability of contrasted populations, i.e., same job entry and exit factors and similar health promotion programmes when related to the mortality under study; and (3) comparability of mortality information, i.e., same diagnostic and certification practices for the cause of death of interest between the contrasted populations. The reference causes of death must also satisfy these requirements with the additions that the exposure under study have no effect on the risk of reference causes of death, and that the accuracy of information about the compared occupations be the same as in the context of the index cause of death. Throughout the discussion, an example of exploring cancer risks among lens manufacturing workers is used.

Interactive electronic computing of the mortality odds ratio

An interactive computer program which computes the standardized mortality odds ratio and the standardized proportional mortality ratio has been developed for use in the analysis of occupational mortality studies. The program provides flexibility in the selection of the comparison (unexposed) population, permitting both internal and external comparison, including comparison with the United States general population. Considerable control for potential confounding factors and for differences in information collection procedures can be exercised through careful choice of the comparison population. The user must select the reference cause(s) of death among 55 categories (59 for women). The condition for equivalence of the standardized mortality odds ratio and the standardized mortality ratio will be met when the selected reference cause(s) is unrelated to the exposure. The program reduces the loss of information due to sparse data during stratification by allowing the user to define the length of the age and time intervals. The program is written in Fortran IV and is designed to produce rapid, cost-efficient interactive results on any mainframe computer system.

Cancer risks in the optical manufacturing industry

A mortality odds ratio (MOR) study has been conducted to explore the cancer risks of exposures experienced in the production of optical lenses and metal spectacle frames. Male death certificates were obtained from a Massachusetts town where a large optical industry is located. Craftsmen, foremen, and operatives of non-optical industries, such as woollen textile workers and workers in the optical company with short-term or no exposure, were chosen as reference workers their incomes were similar to those of the exposed workers. Cardiovascular disease (total 714) is chosen as the reference disease to explore cancers (total 232). An excess risk of total cancers observed = 70, expected = 48) has formed among lens workers. The excess may be accounted for mainly by the excess risk of gastrointestinal cancers; the standardised MORs (sMOR) for medium and long-term exposure were 2.2 and 2.5. The excess was especially evident for colorectal cancers; the sMORs for medium and long-term exposures were 3.2 and 2.6. Excess risks of gastrointestinal cancers (sMOR = 2.9) and colorectal cancers (sMOR = 3.4) were found among metal frame workers with long-term (employed for more than 29 years) exposure, but the number of exposed cases was small (9 and 6 respectively). These results suggest that exposure to abrasives or cutting oil mists or both, possibly by ingestion, might increase the risk of gastrointestinal (especially colorectal) cancers among lens and metal spectacle frame manufacturers.

Occupational mortality studies. Principles of validity

Two common practices of occupational mortality studies have no model in experimentation: (a) the use of the "general population" as a reference population and (b) the use of the total number of deaths as a surrogate for the population-time of follow-up. The former tends not to secure validity in terms of (i) comparability of effects, ie, identity of the extraneous effects of the compared experiences; (ii) comparability of populations, ie, absence of intractable confounding; and (iii) comparability of information, ie, identity of the certification of deaths from the illness of interest for the contrasted populations. The use of a carefully selected, occupational reference population is necessary for all three types of comparability. When deaths from other (auxiliary) diseases are used to estimate the relative magnitudes of the compared populations, careful selectivity is again called for. With respect to auxiliary causes of death, also, the compared occupational populations must satisfy all three aspects of comparability, with the added requirement that the exposure under study have no effect. The "healthy worker effect" is the result of failure to use comparable reference populations in occupational mortality studies.

An alternative to the proportionate mortality ratio

The conditions that are generally considered to justify the use of the proportionate mortality ratio (PMR) to compare exposed and nonexposed populations also permit the computation of the ratio of mortality odds between the cause (of death) of interest and the "other" causes considered. This mortality odds ratio (MOR) comparing the exposed with the nonexposed equals the exposure odds ratio comparing deaths from the cause of interest with those from the auxiliary ("other") causes, and, in contrast to the PMR, it can be interpreted as the observed-to-expected ratio or the standardized mortality ratio on the assumption that the mortality rate for the auxiliary causes is unrelated to the exposure. Related to this, the MOR is free of the arbitrary element in the PMR, which is dependent on the size of the auxiliary-causes domain. These properties make the proposed measure superior to the PMR statistic. Consideration of the proposed statistic for "PMR data" also underscores the need to view "PMR studies" as case-referent studies, and this has important implications for the choice of the auxiliary causes (reference series).