A case-control study of cancer of the nose and paranasal sinuses and occupational exposures.

The association between nasal cancer and various occupations was investigated in a case-control study in the provinces of Verona and Vicenza (northeastern Italy) and Siena (central Italy). Cases of malignant epithelial neoplasm of the nasal cavities and paranasal sinuses diagnosed in the years 1982-1987 in the hospitals of Verona, Legnago, Bussolengo, Vicenza, and Siena comprised the study. Controls were patients admitted to the same hospitals as the cases, with any diagnosis except chronic rhino-sinusal disease and nasal bleeding. Age, gender, residency, and date of admission were taken into account by matching. Cases and controls, or their next of kin, were interviewed or required to fill in a mailed questionnaire; the overall response rate was 70%. Altogether, 78 cases and 254 controls provided information on occupational history. Significantly increased risks were associated (in males) with work in the wood industry (odds ratio [O.R.]: 5.8; 90% confidence interval [C.I.]: (2.2-16) and in the leather industry (6.8; 1.9-25). Textile workers, furnacemen, construction workers, and workers with possible exposure to organic dusts showed increased risks even if statistical significance was not reached.     

Lung cancer risk and talc not containing asbestiform fibres: a review of the epidemiological evidence

A literature search was done and all epidemiological cancer studies mentioning talc as a risk factor were selected. The talc exposed populations were divided into three groups: (1) populations in which no other occupational carcinogen was mentioned (only talc millers satisfied this criterion); (2) populations of talc miners exposed to talc, quartz, and/or radon; and (3) other industrial populations in which talc is associated with quartz, nitrosamines, and asbestos depending on the study. No excess lung cancer mortality was found for the populations of talc millers exposed to high levels of talc but without any other potential carcinogen (SMR = 0.92, 42 cases) while the summary of mortality of talc miners exposed to quartz and/or radon was in excess (fixed effect SMR = 1.20, random effect RR = 1.85, 40 cases). Six studies in other industrial settings were identified. All reported increased lung cancer mortality among talc exposed workers but the talc exposure was confounded with other carcinogens and only one study was able to adjust on them. In conclusion, no increased lung cancer mortality was observed among talc millers despite their high exposure experience. In populations in which talc was associated with other potential carcinogens, some lung cancer excesses were observed.     

Epidemiological study of nasal and nasopharyngeal cancer and their relation to phenoxy acid or chlorophenol exposure

Soft tissue sarcoma and malignant lymphoma have been related to exposure to chlorinated phenoxy acids or chlorophenols as well as exposure to organic solvents and malignant lymphoma. However, colon cancer studied by the same case-referent design did not show any such associations, which helps to rule out alleged systematical bias of the study approach. Further considerations about exposure routes for phenoxy acids and chlorophenols suggested that nasal and nasopharyngeal cancers should be studied. Forty-four cases with nasal cancer and 27 cases with nasopharyngeal cancer were eligible for study during 1970-1979 together with 541 referents, as utilized also in the aforementioned studies. Exposure to phenoxy acids gave formally a doubled but insignificant risk for the studied cancer types. Exposure to chlorophenols, as present particularly in woodwork, was related to an about sevenfold and significant increase in the risk for both cancer types. In woodworkers without exposure to chlorophenols there was an approximate normal risk, but cabinet makers, even without exposure to chlorophenols, had nearly doubled (but insignificant) risk of nasal cancer.     

Effect of different questionnaire formats on reporting of occupational exposures

During an exposure monitoring study, 78 saw maintenance tradesmen were randomly assigned to be interviewed about their exposures using one of two questionnaire formats: open-ended and partly prompted questions about five categories of materials; and detailed prompting about 75 agents. The more open-ended questionnaire elicited fewer exposure responses overall, but more responses about agents not included on the detailed questionnaire. Composite materials and trade name products were more frequently cited as exposures than individual metals or compounds. Validity of responses was ascertained using air measurements (individual metals) or observations of the employees (composite materials). Sums of sensitivities and specificities were very low (near 1.0) for most of the metals for both types of questionnaire. For composite materials, validity improved substantially. Sensitivities with the partly prompted format (0.44–0.85) were always lower than with detailed prompting (0.80–1.00). Specificities were usually, but not always, higher with partial prompting (0.66–0.92) than with detailed prompting (0.18–0.86). Selection of questionnaire format for an epidemiologic study would depend on the likely prevalence of exposure in controls and the effects of trade-offs in sensitivity and specificity.     

Use of death certificates in epidemiological studies, including occupational hazards: variations in discordance of different asbestos-associated diseases on best evidence ascertainment.

There is extensive information on discordance in general between accuracy of medical diagnoses on death certificate categorization of cause of death and available clinical and histopathological data. This is as true for occupational disease as for other conditions. But occupational illnesses bear a special problem. Discordance is not equal across the board--it may vary with each occupationally related disease, and no single formula can be applied. It may be high for angiosarcoma and low for acute hydrogen sulfide poisoning, low for bladder cancer, high for unsuspected methyl mercury poisoning. We have found that for one agent--asbestos--there were different rates of discordance for different asbestos-related diseases (e.g., lung cancer, mesothelioma, asbestosis, kidney cancer) among 4,951 deaths studied prospectively from 1967 to 1986. Caution is therefore required before accepting generalizations concerning (unstudied) discordance in occupational mortality studies, and in their use in risk assessment models.     

Respiratory exposures associated with silicon carbide production: estimation of cumulative exposures for an epidemiological study.

Silicon carbide is produced by heating a mixture of petroleum coke and silica sand to approximately 2000 degrees C in an electric furnace for 36 hours. During heating, large amounts of carbon monoxide are released, sulphur dioxide is produced from residual sulphur in the coke, and hydrocarbon fume is produced by pyrolysis of the coke. Loading and unloading furnaces causes exposures to respirable dust containing crystalline silica, silicon carbide, and hydrocarbons. In the autumn of 1980 extensive measurements were made of personal exposures to air contaminants. Eight hour time weighted exposures to sulphur dioxide ranged from less than 0.1 ppm to 1.5 ppm and respirable participate exposures ranged from 0.01 mg/m3 to 9.0 mg/m3. Geometric mean particulate exposures for jobs ranged from 0.1 mg/m3 to 1.46 mg/m3. The particulate contained varying amounts of alpha-quartz, ranging from less than 1% to 17%, and most quartz exposures were substantially below the threshold limit value of 100 micrograms/m3. Only traces of cristobalite (less than 1%) were found in the particulate. Median exposures to air contaminants in each job were estimated. Since the operations at the plant had been stable over the past 30 years, it was possible to estimate long term exposures of workers to sulphur dioxide, respirable particulate, quartz, total inorganic material, and extractable organic material. Cumulative exposure (average concentration times exposure duration) for each of the air contaminants was estimated for each worker using his job history. There was sufficient independent variability in the sulphur dioxide and respirable particulate cumulative exposures to make an assessment of their independent effects feasible. The theoretical basis for using the cumulative exposure index and its shortcomings for epidemiological applications were presented.     

Influence of occupational diving upon the nervous system: an epidemiological study

Neurological signs and symptoms were recorded from 156 air and saturation divers and 100 controls. Fifty one (33%) of the divers had had symptoms from the central nervous system during decompression. Also, 22 (14%) had been unconscious while diving. In total 79 (51%) had had decompression sickness (DCS). Twelve (8%) of the divers and no controls had had specific neurological symptoms (vision disturbances, vertigo, reduced skin sensitivity) in non-diving situations, and six (4%) of the divers (no controls) had had episodes of cerebral dysfunction (seizures, transient cerebral ischaemia, transient amnesia). The divers had significantly more general symptoms from the nervous system and more abnormal neurological findings than the controls. The most prominent symptoms were difficulties in concentration and problems with long and short term memory. The most prominent abnormal findings in the divers were compatible with dysfunction in the distal spinal cord or nerve roots, and polyneuropathy. The general neurological symptoms and findings were independently significantly correlated with diving exposure, prevalence of DCS, and age.     

Residential Radon and Risk of Lung Cancer in an Italian Alpine Area

To evaluate whether residential radon exposure explains the excess mortality for lung cancer in an Italian alpine valley with high natural radioactivity, the authors conducted a population-based case-control study on 138 deceased cases and 291 sex- and year-of-birth-matched controls. Year-long alpha-track measurements of radon were performed in the most recent residence, and information about occupational history and lifetime smoking habits was obtained. The authors adjusted for smoking, and radon was associated with lung cancer risk among men: compared with a radon level of < 40 becquerels (Bq) per cubic meter (m³), the odds ratios for 40–76 Bq/m³, 77–139 Bq/m³, 140–199 Bq/m³, and 200+ Bq/m³ were 2.1, 2.0, 2.7, and 1.4, respectively. The association between radon and lung cancer, as determined with a multiplicative model, was found only among male smokers.     

Influence of occupational diving upon the nervous system: an epidemiological study.

Neurological signs and symptoms were recorded from 156 air and saturation divers and 100 controls. Fifty one (33%) of the divers had had symptoms from the central nervous system during decompression. Also, 22 (14%) had been unconscious while diving. In total 79 (51%) had had decompression sickness (DCS). Twelve (8%) of the divers and no controls had had specific neurological symptoms (vision disturbances, vertigo, reduced skin sensitivity) in non-diving situations, and six (4%) of the divers (no controls) had had episodes of cerebral dysfunction (seizures, transient cerebral ischaemia, transient amnesia). The divers had significantly more general symptoms from the nervous system and more abnormal neurological findings than the controls. The most prominent symptoms were difficulties in concentration and problems with long and short term memory. The most prominent abnormal findings in the divers were compatible with dysfunction in the distal spinal cord or nerve roots, and polyneuropathy. The general neurological symptoms and findings were independently significantly correlated with diving exposure, prevalence of DCS, and age.     

The risk of adverse reproductive and developmental disorders due to occupational pesticide exposure: an overview of current epidemiological evidence

The epidemiological studies presented in this paper refer to the association between agricultural occupation of parents and the incidence of infertility, congenital malformations, miscarriage, low birthweight, small-for-gestational-age (SGA) birth, preterm delivery and stillbirth. The results of the analyses showed that employment in agriculture increases the risk of specific morphological abnormalities in sperm, including the decreased sperm count per ejaculate and declined percentage of viable sperm. In general, no effect of exposure to pesticides on sexual hormones was observed. The data on the effect of employment in agriculture on the time to pregnancy are unequivocal, but most of them suggest that there is a relationship between the decreased fecundability ratio and pesticide exposure. Nor does the research on the sex ratio of offspring provide explicit results. The analyses indicate that parental employment in agriculture could increase the risk of congenital malformations in the offsprings, particularly such as orofacial cleft, birthmarks in the form of hemangioma as well as musculoskeletal and nervous system defects. The data on the effect of occupational exposure to pesticides on birthweight are inconsistent. Although most of epidemiological studies do not reveal a significantly increased risk of SGA, a slower pace of fetal development corresponding to SGA in the population of women exposed to pyrethroids has been recently reported. There are also some indications that exposure to pesticides may contribute to stillbirth and female infertility. The literature review suggests a great need to increase awareness of workers who are occupationally exposed to pesticides about their potential negative influence on fertility and pregnancy outcome. In the light of existing although still limited evidence of adverse effects of pesticide exposure on fertility during the preconceptual period, it is necessary to reduce the exposure to pesticides.     

Congenital defects of the central nervous system and occupational factors during pregnancy. A case-referent study

The possible impact of occupational factors on the furtherance of congenital defects has been under study at our department for the past four years, and it has assumed a special interest because of the importance to understand the etiology of these disorders and a good possibility for prevention by elimination of the causative factor from the work environment. In connection with a register based case-referent study utilizing supplementary information, acquired by a single interviewer, we analyzed various occupational factors related to pregnancy. We found that organic solvent exposure and exposure to various dusts during the pregnant period were more common among the case mothers than among their matched referents. These findings may offer further rough guidance in the quest for the identification of possibly embryotoxic agents that may occur in occupational life.     

Exposure assessment in occupational epidemiology: measuring present exposures with an example of a study of occupational asthma

The aim of the present paper is to present a comprehensive review of the issues involved in exposure assessment for occupational epidemiology studies and to provide an example. Exposure assessment for occupational epidemiology studies is becoming more quantitatively refined. This paper discusses important issues that need to be taken into account for exposure assessment, with particular reference to occupational asthma. It discusses issues such as survey design, data collection, the effect of measurement error and data interpretation. It presents recently developed methodology to evaluate exposure variability and its effect on the attenuation of risk estimates. It also presents methodology to control for such variability. It uses examples from a recent cohort study of flour millers and bakers. This example shows various characteristics of exposure and demonstrates that various measures of exposure, such as peak and full-shift exposure measurements, are regularly correlated, which has consequences for the analyses of exposure-response relationships. This paper stresses the importance of the recognition and evaluation of exposure variability and its effect on risk estimates and shows that with different exposure grouping schemes, different health risk estimates can be obtained. Quantitative exposure assessment is generally difficult, time-consuming and expensive and many issues need to be taken into account, but it can be rewarding and has become an absolute necessity for many occupational epidemiology studies. Evaluation of components of exposure variance is absolutely necessary. Exposure variability could lead to serious attenuation of risk estimates. Received: 3 July 1996 / Accepted: 2 April 1997     

Olfactory toxicity: long-term effects of occupational exposures

Objective: To present and discuss the results of research on olfactory function impairments related to chronic occupational exposure to industrial chemicals. Methods: This review is mainly focused on the results of epidemiological studies on olfactory function, evaluated using quantitative testing methods, in workers chronically exposed to airborne industrial chemicals. Papers published in peer-reviewed scientific journals were mainly considered. Results: The prevalence of olfactory impairments related to occupational exposure to chemicals is unknown: frequencies ranging 0.5–5% of all olfactory dysfunctions have been proposed, considering both exposure to chemicals and the use of pharmaceutical drugs, but the real relevance of this problem is possibly overlooked, especially considering that occupational exposure may account for a significant part of “idiopathic” smell disorders, i.e., the 10–25% of all olfactory problems within the general population. An adverse effect has been reported in workers chronically exposed to some metals as cadmium, chromium, manganese, arsenic, mercury, and organic lead, and to other chemicals as acrylates, styrene, and solvent mixtures. The results of relevant studies are discussed. A problem in the evaluation of data is that different methods have been applied in different studies, affecting the comparability of results. Conclusions: To date, knowledge of the effect of chronic occupational exposure to industrial chemicals on olfactory function is largely incomplete, but supports the hypothesis that olfactory neuroepithelium is susceptible to environmental exposures to chemicals. Occupational-related olfactory impairment is usually sub-clinical, and can be only detected using adequate quantitative olfactory function testing procedures. Available data show the need for further good quality research in this field.