Cancer mortality and incidence in mastic asphalt workers.
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Adolescent↗
Biomedical subjects
O Wong
Publications and source records attributed to O Wong.
An updated study of taconite miners and millers exposed to silica and non-asbestiform amphiboles.
This is the second update of a study of 3,444 taconite miners and millers who were first exposed to taconite, with associated exposures to silica and nonasbestiform amphiboles, in the period 1947 through 1958. Previous analyses of deaths through 1977, and again through 1983, showed no significant excess deaths from any specific causes. The present study continues the follow-up through 1988, adding 14,748 person-years of observation and 261 death certificates for analysis. The population, reduced to 3,431 because of the detection of 13 earlier duplications, has now been observed for 101,055 person-years, with 1,058 deaths and 1,039 death certificates. Death certificates were obtained for 98.2% of those known to be dead. The total number of deaths was significantly fewer than expected. Based on US rates, the standardized mortality ratio (SMR) was 83 (ie, 83% of expected). Based on Minnesota death rates, it was 91. With both US and Minnesota death rates, the SMRs for malignant neoplasms, cancer of the respiratory tract, cancer of the digestive system, heart disease, nonmalignant respiratory disease, and cirrhosis of the liver were all below 100. Slightly elevated SMRs were found for cancer of the colon, cancer of the kidney, and lymphopoietic cancer. These elevations were not statistically significant. Separate analyses were made of total deaths, lung cancer deaths, and kidney cancer deaths in men who had worked with taconite for time periods of less than 1 year, 1-5 years, 5-10 years, and over 10 years, during observation periods less than 10 years, 10-20 years, and over 20 years.(ABSTRACT TRUNCATED AT 250 WORDS)
Dust↗
Mortality among workers exposed to ethylene oxide.
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Ethylene Oxide↗
An industry-wide epidemiologic study of vinyl chloride workers, 1942-1982.
The cohort consisted of 10,173 men who had worked for at least one year in jobs involving exposure to vinyl chloride prior to 1 January 1973. These men were employed at 37 plants in the U.S., belonging to 17 companies. Observation of the mortality experience of the cohort was updated from 31 December 1972 to 31 December 1982 (the study now covering 1942-1982). A total of 1,536 cohort members were identified as having died. The observed mortality, by cause, was compared with the expected based on U.S. mortality rates, standardized for age, race, and calendar time. Analyses by length of exposure, latency, age at first exposure, calendar year of first exposure, and type of products were performed. The study confirmed that the vinyl chloride workers experience a significant mortality excesses in angiosarcoma (15 deaths), cancer of the liver and biliary tract (SMR = 641), and cancer of the brain and other central nervous system (SMR = 180). In addition, the study also found a significant mortality excess in emphysema/chronic obstructive pulmonary disease (COPD) (SMR = 179). On the other hand, the study did not find any excess in either respiratory cancer or lymphatic and hematopoietic cancer. This study also found an increase in biliary tract cancers, independent from liver cancer.
Adult↗
A case-control study of lung cancer in a cohort of workers potentially exposed to slag wool fibres.
A cohort of 4841 men were identified as having worked for more than a year at nine slag wool plants. Some of these men were potentially exposed to man made vitreous fibres (MMVF). The vital status of the entire cohort was ascertained to the end of 1989. Of the 504 deaths that occurred between 1970 and 1989, 61 were attributed to lung cancer (cases). Individually matched controls were randomly selected from the remaining deaths. Attempts were made to locate and interview the surviving families of the cases and controls. The families of three lung cancer cases could not be located and no matched controls were found for another three cases. Included in the final analysis were 55 cases and 98 controls. Estimates of individual exposure to MMVF were based on employment records and industrial hygiene surveys. Data on smoking and histories of employment outside the MMVF industry were obtained from telephone interviews and employment records. Relative risks were calculated for cigarette smoking and exposure to MMVF. No increased risk of lung cancer was found associated with exposure to MMVF, and analysis by cumulative fibre exposure did not indicate any trend. As expected, cigarette smoking was found to be responsible for the observed increase in mortality from lung cancer in this group of MMVF workers, and the risk increased with increasing pack-years of cigarette smoking.
Aged↗
Proper interpretation of meta-analysis in occupational epidemiological studies: a response.
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Data Interpretation, Statistical↗
A cohort mortality study and a case-control study of workers potentially exposed to styrene in the reinforced plastics and composites industry.
The cohort consisted of 15,908 men and women who worked for at least six months between 1948 and 1977 in 30 participating manufacturing plants in the reinforced plastics and composites industry. These workers were occupationally exposed to the working environment in the industry, which included exposure to styrene. Cause specific mortality analyses were performed based on the standardised mortality ratio (SMR) with the United States population as a comparison. No significant excess of cause specific mortality was found for the total cohort. Mortality from cancer was slightly less than expected (SMR = 88.1). For cancer of the respiratory system, a small non-significant excess was detected (SMR = 116.1). For lymphatic and haematopoietic cancer, a non-significant deficit was found (SMR = 73.3). The observed mortality from leukaemia was similar to that expected (five observed v 4.76 expected deaths). The plants with hot processes (injection moulding, centrifugal casting, compression moulding, continuous lamination, and pultrusion) experienced a significantly increased SMR (177.9) for respiratory cancer, which was more than twice that (78.3) for those with cold processes (resin mixing, lay up and spray up, bag moulding, and filament winding). As potential exposure to styrene from hot processes is considerably less than that from the cold processes, this finding could not be attributed to occupational exposures. A subsequent nested case-control study consisting of 40 cases of deaths from respiratory cancer was conducted. Further information on detailed work history, occupational exposures, and smoking history was collected. The case-control study did not show any significant association between respiratory cancer and direct exposure to styrene (contained in polyester resins), duration of exposure to styrene, the type of process (hot or cold), or whether a resin was used. A statistically significant association (relative risk = 7.33) was found between cigarette smoking and respiratory cancer among the study subjects.
Case-Control Studies↗
Effect of prostaglandin, leukotriene, and arachidonic acid on experimental otitis media with effusion in chinchillas.
Although previous studies have shown that prostaglandins (PGs), leukotrienes (LTs), and other arachidonic acid (AA) metabolites play an important role in the pathogenesis of otitis media with effusion (OME), the exact role of each AA metabolite in OME is still unknown. The purpose of this study was to examine the effect of several individual AA metabolites alone or in combination and AA itself on experimental otitis media in chinchillas. Normal chinchillas were inoculated daily with normal saline, PGE2, LTC4, LTC4 + PGE2, and AA through the superior bullae over 7 days. Animals were followed by otoscopy and tympanometry, samples of middle ear effusion were collected for biochemical assay, and temporal bones were processed for histopathology. The highest number of ears that developed OME was in the group inoculated with PGE2 + LTC4. The degree of inflammatory change was more pronounced in groups injected with LTC4 than any other group. The findings of this study suggest that eicosanoids PGE2, LTC4, and AA alone or in combination inoculated into the middle ear can induce OME.
6-Ketoprostaglandin F1 alpha↗
Critical review of cancer epidemiology in petroleum industry employees, with a quantitative meta-analysis by cancer site.
A critical review of close to 100 published and unpublished but otherwise available epidemiologic reports of petroleum industry employees from the United States, United Kingdom, Canada, Europe, Australia, and Japan was conducted. Analyses by duration of employment and latency are discussed, and summary standardized mortality ratios (SMRs) or meta-SMRs are developed for selected cancer sites. Findings indicate that the industry experienced a significantly lower cancer mortality than the general population for all cancer sites combined, digestive system, stomach, and lung. For the industry as a whole, SMRs similar to the general population were observed for skin, brain, pancreatic, prostatic, and kidney cancers. However, some data indicate that certain small groups within the industry might have elevated prostatic and kidney cancer risk. This review supports the conclusion that some refinery employees, particularly those employed before the 1940s, may have been at increased risk of leukemia. There is some indication that cancer of other lymphatic tissue may also be elevated. Unresolved issues affecting these conclusions are discussed, and specific directions for future research are offered.
Benzene↗
An epidemiologic investigation of birth outcomes in relation to dibromochloropropane contamination in drinking water in Fresno County, California, USA.
This report describes an epidemiologic investigation of the relationship between dibromochloropropane (DBCP), contamination in drinking water and birth outcomes between 1978 and 1982 in Fresno County, California, USA. Census tracts in the county were categorized according to DBCP level in drinking water. A direct comparison between exposure categories was done by the use of the Mantel-Haenszel chi-square procedure to compute relative ratios or risks for low birth weight and birth defect, adjusting for age, race, percent Hispanic, and parity. No correlation between these birth outcomes and DBCP contamination was found. In addition, we did not find any difference in sex ratio in relation to DBCP contamination.
Adolescent↗
Facilitated transport of basic and acidic drugs in solutions through snakeskin by a new enhancer--dodecyl N,N-dimethylamino acetate.
The permeation characteristics of two model drugs, clonidine (basic) and indomethacin (acidic), were studied by determining their penetration fluxes through hydrated shed snakeskins (Elaphe obsoleta) at 32 degrees C. The drugs were formulated in buffers of different pH's, ranging from 3 to 7. The total penetration fluxes at pH 7.0 for both compounds using skins pretreated with dodecyl N,N-dimethylamino acetate were at least 11 times higher than those of the control runs without enhancer treatment. Equations were derived to calculate the permeability coefficients (Ki) and fluxes (Ji) for the ionized and the nonionized species to allow for comparison of their penetration ability through the model membrane. The permeability coefficient of clonidine is 2.50 x 10(-3) cm/hr for the nonionized form and 2.41 x 10(-4) cm/hr for the protonated form. This result indicates that the nonionized form penetrates the skins better than the ionized form. Both permeability coefficient values are 11 times larger than the corresponding values obtained from the control skins. The total flux of clonidine is dependent on its initial concentration in the donor cell but is independent of the ionic strength of the solution formulations. The penetration characteristics of indomethacin are similar to those of clonidine, with a higher permeability coefficient of the nonionized form (3.90 x 10(-3) cm/hr) than of the ionized form (7.97 x 10(-4) cm/hr) using pretreated skins. While the enhancer shows 24 times penetration enhancement of the ionized form of indomethacin, it does not enhance the penetration of the nonionized species.
Animals↗
New alkyl N,N-dialkyl-substituted amino acetates as transdermal penetration enhancers.
New alcohol derivatives of N,N-disubstituted amino acids with a low toxicity have been synthesized and evaluated for their transdermal penetration enhancing effects on the transport of indomethacin from petrolatum ointments across shed skin of black rat snake (Elaphe obsoleta). The derivatives show excellent penetration enhancement of indomethacin, as high as 3.8 times that of Azone, with decyl N,N-dimethylamino acetate as the lead compound in the series. The release of indomethacin from an ointment containing 1% indomethacin, 5% dodecyl N,N-dimethylamino acetate, and 94% petrolatum was 3.15 micrograms/min1/2/cm2. Saturation studies performed by incorporating varying concentrations of indomethacin, from 0.1 to 10%, into the ointments and determination of the fluxes of indomethacin demonstrated that the saturated concentration of indomethacin in petrolatum base was approximately 1%. Penetration fluxes of indomethacin (1%) through snake skin increased linearly as the concentration of dodecyl N,N-dimethylamino acetate increased from 2.5 to 15%. Experiments involving the pretreatment of the snake skins with dodecyl N,N-dimethylamino acetate indicated that pretreatment of the skin increased the skin permeability significantly. Electron micrograph studies on the snake skin treated with dodecyl N,N-dimethylamino acetate show clearly that the enhancer interacted with both the lipid-rich layer (mesos phase) and the keratin-rich layers (both alpha and beta phases).
Alkanes↗
Ecological analyses and case-control studies of gastric cancer and leukaemia in relation to DBCP in drinking water in Fresno County, California.
Through ecological analyses and case-control studies, the possible relation of gastric cancer and leukaemia to dibromochloropropane (DBCP) contamination of drinking water in Fresno County, California, has been examined. The ecological analyses examined the correlation between gastric cancer and leukaemia (including the lymphatic varieties), mortality rates, and DBCP concentrations in drinking water by census tract in Fresno County, 1960-83. No correlation was found between gastric cancer or leukaemia and DBCP. The gastric cancer case-control study consisted of 263 deaths from gastric cancer in the county, 1975 to mid-1984, and 1044 controls, using information on residential history and occupation of both cases and controls. Analyses were based on residence at death, as well as one and ten years before death. The case-control study did not find any relation between gastric cancer and DBCP in drinking water. Hispanics in the county were found to experience a relative risk of gastric cancer of 2.77, compared with non-Hispanics. A similar case-control study consisting of 259 cases of leukaemia and 1161 controls found no relation between all leukaemia or lymphatic leukaemia and DBCP in drinking water. Farm workers, however, do appear to have an increased risk of leukaemia.
Agricultural Workers' Diseases↗
A cohort mortality study of employees exposed to chlorinated chemicals.
The cohort of this historical prospective mortality study consisted of 697 male employees at a chlorination plant. A majority of the cohort was potentially exposed to benzotrichloride, benzyl chloride, benzoyl chloride, and other related chemicals. The mortality experience of the cohort was observed from 1943 through 1982. For the cohort as a whole, no statistically significant mortality excess was detected. The overall Standardized Mortality Ratio (SMR) was 100, and the SMR for all cancers combined was 122 (not significant). The respiratory cancer SMR for the cohort as a whole was 246 (7 observed vs. 2.8 expected). The excess was of borderline statistical significance, the lower 95% confidence limit being 99. Analysis by race showed that all 7 respiratory cancer deaths came from the white male employees, with an SMR of 265 (p less than 0.05). The respiratory cancer mortality excess was higher among employees in maintenance (SMR = 229) than among those in operations or production (SMR = 178). The lung cancer mortality excess among the laboratory employees was statistically significant (SMR = 1292). However, this observation should be viewed with caution, since it was based on only 2 deaths. Further analysis indicated that the respiratory cancer mortality excess was limited to the male employees with 15 or more years of employment (SMR = 379, p less than 0.05). Based on animal data as well as other epidemiologic studies, together with the internal consistency of analysis by length of employment, the data suggest an association between the chlorination process of toluene at the plant and an increased risk of respiratory cancer.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Substituent effects on partition coefficients of barbituric acids.
Precise partition coefficients in 1-octanol-water at 25 degrees C were determined for three 2-thiobarbituric acids and 14 barbituric acids with a wider range of substituents. The experimental log P values (log Pexp) of barbituric acids were correlated with the carbon number and the branching effect of the C5 substituent(s) by linear regression analysis. The carbon number term makes a major contribution to the partition coefficients. The contribution of the polar effect of the C5 substituents was insignificant in contrast to a previous report. Hydrophobic constants (pi) were determined for allyl, phenyl, and chloro-substituents, and these empirical pi values gave much closer predicted calculated log P (log Pcalc) values when applied to the reported log Pexp values.
Barbiturates↗
Unsaturated cyclic ureas as new nontoxic biodegradable transdermal penetration enhancers I: Synthesis.
A new concept was implemented to reduce the toxicity of some new biodegradable transdermal penetration enhancers. These enhancers consist of 1-alkyl-4-imidazolin-2-one and a long-chain alkyl ester group at the N-3 position. The synthesis involves N-alkylation of the parent compound with soft alkylating agents which were prepared in high yields by an improved method. A phase transfer catalysis technique using KOH as the base, tetrabutylammonium bromide as the catalyst, and toluene as the solvent was found to be most effective in the N-alkylation step.
Adjuvants, Pharmaceutic↗
An epidemiologic investigation of the relationship between DBCP contamination in drinking water and birth rates in Fresno County, California.
This report describes an epidemiologic investigation of the relationship between DBCP (dibromochloropropane) contamination in drinking water and birth rates between 1978 and 1982 in Fresno County, California. Census tracts in the county were categorized according to DBCP level in their drinking water. Standardized birth ratios and relative birth ratios (adjusted for age, race, per cent Hispanic, and parity) were calculated for these census tracts. No relation between birth ratios and DBCP contamination in drinking water was found.
Adult↗
Problems associated with collecting drinking water quality data for community studies: a case example, Fresno County, California.
This paper discusses methodology in developing exposure data for the water supply contaminant dibromochloropropane (DBCP) in Fresno County, California. There are 532 drinking water systems (49 large and 483 small) within Fresno County plus 14,000 private wells. We determined the number of wells per system, the output per well, and the population served by each system. The task of deriving water quality estimates for each census tract was complicated by the fact that a single census tract can be served by more than one system; each system usually has more than one well; and a single well can have several episodes of testing for various contaminants. We calculated a series of weighted averages for concentrations of DBCP, arsenic, and nitrates for each census tract, using water production figures for each well as the weighting factor. Water quality data were derived from a total of 14,861 laboratory reports, although the majority did not report on all contaminants. Mean DBCP levels ranged from 0.0041 ppb to 5.7543 ppb among the census tracts. We found no correlation between DBCP levels per census tract compared to either arsenic or nitrates. We believe that we made as complete an exposure assessment as practically feasible.
Arsenic↗