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C A Veys

Publications and source records attributed to C A Veys.

16 recordsLinked to original sources
PubMed2004

Bladder tumours in rubber workers: a factory study 1946-1995.

BACKGROUND: Prior to December 1949, some British rubber industry workers were inadvertently exposed to the human bladder carcinogen beta-naphthylamine, which was present as a contaminant (at 0.25%) in antioxidants used in manufacturing. This study follows a composite cohort of 6450 men employed at a large tyre factory either during the 'at-risk' period or just after it. METHODS: A group of 2090 at-risk men (employed 1945-1949) and 3038 men, first employed only after January 1950, when the carcinogen had been removed, were followed for their bladder cancer morbidity and mortality experiences. RESULTS: Fifty-eight tumours were registered for those at risk, whereas only 33.9 were expected at national standardized registration rates [SRRN = 171 and 95% confidence interval (CI) = 130-221]. Thirty-nine bladder tumours were reported for the post-1950 intake, whereas 38.3 were expected (SRRN = 102 and 95% CI = 72-139). The use of mortality data did not reveal any underlying hazard because 12 of the 58 at-risk workers with tumours were still alive at the study end date. In only 16 instances was bladder cancer actually certified as the underlying cause of death. Plotting cases by their location of work on a factory plan assisted the interpretation. CONCLUSIONS: A statistically significant elevated risk of bladder cancer for the exposed workforce was evident, but this reversed when the carcinogen was removed from processing in October 1949. The use of morbidity (incidence) data in long-term studies of occupational bladder cancer should be the required methodology if the hazard and risk are not to be underestimated.

2-Naphthylamine↗
PubMed2004

A study of mortality patterns at a tyre factory 1951-1985: a reference statistic dilemma.

BACKGROUND: The general and cancer mortalities of rubber workers at a large tyre factory were studied in an area of marked regional variation in death rates. METHODS: Three quinquennial intakes of male rubber workers engaged between January 1946 and December 1960 formed a composite cohort of 6454 men to be followed up. Over 99% were successfully traced by December 1985. The cohort analysis used both national and local rates as reference statistics for several causes. RESULTS: Between 1951 and 1985, a national standardized mortality ratio (SMRN) of 101 for all causes (based on 2556 deaths) was noted, whereas the local standardized mortality ratio (SMRL) was only 79. For all cancers, the figures were 115 (SMRN) and 93 (SMRL), for stomach cancer they were 137 (SMRN) and 84 (SMRL), and for lung cancer they were 121 (SMRN) and 94 (SMRL). No outright excesses against the national norm were observed for other cancers except for larynx, brain and central nervous system and thyroid cancer and the leukaemias. Excesses were statistically significant for cancer of the gallbladder and the bile ducts, for silicotuberculosis (SMRN = 1000) and for the pneumoconioses (SMRN = 706). Deaths from cerebrovascular diseases, chronic bronchitis and emphysema showed statistically significant deficits using either norm. CONCLUSIONS: These results from a large factory cohort study of rubber workers, followed for over three decades, demonstrate the marked discrepancy that can result from using only one reference statistic in areas of significant variation in mortality patterns.

Aged↗
PubMed1993

Towards causal inference in occupational cancer epidemiology--II. Getting the count right.

This second paper in the series assessing causal inference in occupational cancer epidemiology highlights the importance of using the right data sources when examining the association between exposure and tumour incidence in groups of workers. Using the wrong ones can lead to omissions which become insidious and cumulative during a long-term follow-up study, often extending over several decades. The main cause is the changing survival pattern of some cancers and it is a new and important factor to be taken into account. This was illustrated during an in-depth study of an excess of bladder cancer at a large tire factory, where the workforce was exposed to beta-naphthylamine-contaminated antioxidants used in processing. At first the study was confined to a mortality analysis using death certificates to identify those whose underlying cause of death was bladder cancer [International Classification of Diseases (8th Rev.), No. 188]. It soon became apparent, however, that several cases had outlived the study end-date, or had died of an unrelated cause, often with bladder cancer not being mentioned anywhere on the death certificate. The study was then changed also to include morbidity (incidence) data using cancer registration. Between 1946 and 1949 some 2090 men were exposed to two antioxidants contaminated with about 0.2% of beta-naphthylamine. Altogether there were 45 bladder tumours relevant to this 'at risk' group, whereas only 24.8 were expected at the national incidence rates (P < 0.001), which clearly reflects the group's exposure to a recognized bladder carcinogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Causality↗
PubMed1990

Towards causal inference in occupational cancer epidemiology--I. An example of the interpretive value of using local rates as the reference statistic.

A brief overview is made of the criteria currently applied for establishing causation in occupational cancer epidemiology, and further criteria or 'desiderata' are proposed. These supplement the present somewhat simplistic ones for 'sufficient evidence of carcinogenicity' advocated by the International Agency for Research against Cancer in their monograph series. A frequent cause of confounding, not always appreciated, is the limited choice of a reference population for the statistical analyses. The study population is often an industrial one with marked regional and urban biases, especially for some of the cancers under scrutiny: these biases can influence markedly the resultant Standardized Mortality Ratio (SMR) calculated, and thus lead to misleading conclusions. The British Rubber Manufacturers' Mortality Study, 1946-1980, provided an opportunity to extract the data set of one of the 13 factories involved. Both local and national death rates were applied as a reference, and the use of the former substantially reduced the high SMRs previously recorded for lung and stomach cancers. This emphasized the need for further analyses when making other internal comparisons in order to accommodate more of the 'desiderata' listed. Ultimately causation can be inferred only after weighing up all the evidence, and must be based on a 'balance of probabilities'.

Data Interpretation, Statistical↗
PubMed1989

Mortality in the British rubber industry 1946-85.

The mortality experienced by a cohort of 36,691 rubber workers during 1946-85 has been investigated. These workers were all male operatives first employed in any one of the 13 participating factories in 1946-60; all had worked continuously in the industry for a minimum period of one year. Compared with the general population, statistically significant excesses relating to cancer mortality were found for cancer of the pharynx (E = 20.2, O = 30, SMR = 149), oesophagus (E = 87.6, O = 107, SMR = 122), stomach (E = 316.5, O = 359, SMR = 113), lung (E = 1219.2, O = 1592, SMR = 131), and all neoplasms (E = 2965.6, O = 3344, SMR = 113). Statistically significant deficits were found for cancer of the prostate. (E = 128.2, O = 91, SMR = 71), testis (E = 11.0, O = 4, SMR = 36), and Hodgkin's disease (E = 26.9, O = 16, SMR = 59). Involvement of occupational exposures was assessed by the method of regression models and life tables (RMLT). This method was used to compare the duration of employment in the industry, the duration in "dust exposed" jobs, and the duration in "fume and/or solvent exposed" jobs of those dying from causes of interest with those of all matching survivors. Positive associations (approaching formal levels of statistical significance) were found only for cancers of the stomach and the lung. The results of the RMLT analysis are independent of those from the SMR analysis, and the study continues to provide limited evidence of a causal association between the risks of stomach cancer and dust exposures, and the risks of lung cancer and fume or solvent exposures in the rubber industry during the period under study.

Adolescent↗
PubMed1986

Cancer mortality in the British rubber industry: 1946-80.

The mortality experienced by a cohort of 36445 rubber workers during 1946-80 has been investigated. These workers were all male operatives first employed in any one of the 13 participating factories in 1946-60; all had worked continuously in the industry for a minimum period of one year. Compared with the general population, statistically significant excesses relating to cancer mortality were found for cancer of the stomach (E = 245.9, O = 282, SMR = 115), primary cancer of the liver (E = 12.8, O = 22, SMR = 172), cancer of the lung (E = 892.7, O = 1191, SMR = 133), and all neoplasms (E = 2165.2, O = 2487, SMR = 115). Statistically significant deficits were found for cancer of the prostate (E = 79.7, O = 59, SMR = 74) and cancer of the testis (E = 10.3, O = 4, SMR = 39). The method of regression models in life tables (RMLT) was used to compare the duration of employment in the industry, the duration in "dust exposed" jobs, and the duration in "fume and/or solvent exposed" jobs of those dying from causes of interest with those of all matching survivors. Significant positive associations were found only for cancer of the stomach and cancer of the lung. The results of the RMLT analysis are independent of those from the SMR analysis, and the study has provided further evidence of a causal association between the risks of lung and stomach cancer and certain occupational exposures in the rubber industry.

Adolescent↗
PubMed1982

Cancer mortality in the British rubber industry.

Although it is over 30 years since an excess of bladder cancer was first identified in British rubber workers, the fear has persisted that this hazard could still be affecting men working in the industry today. Furthermore, suspicions have also arisen that other and hitherto unsuspected excesses of cancer might be occurring. For these reasons 33 815 men, who first started work in the industry between 1 January 1946 and 31 December 1960, have been followed up to 31 December 1975 to ascertain the number of deaths attributable to malignant disease and to compare these with the expected number calculated from the published mortality rates applicable to the male population of England and Wales and Scotland. The findings confirm the absence of any excess mortality from bladder cancer among men entering the industry after 1 January 1951 (the presumed bladder carcinogens were withdrawn from production processes in July 1949), but they confirm also a statistically significant excess of both lung and stomach cancer mortality. A small excess of oesophageal cancer was also observed in both the tyre and general rubber goods manufacturing sectors. American reports of an excess of leukaemia among rubber workers receive only limited support from the present study, where a small numerical excess of deaths from leukaemia is not statistically significant. A special feature of the study is the adoption of an analytical method that permits taking into account the long latent period of induction of occupational cancer.

England↗