End-stage renal disease incidence in a cohort of US firefighters from San Francisco, Chicago, and Philadelphia.

BACKGROUND: Firefighters perform strenuous work in hot environments, which may increase their risk of chronic kidney disease. The purpose of this study was to evaluate the risk of end-stage renal disease (ESRD) and types of ESRD among a cohort of US firefighters compared to the US general population, and to examine exposure-response relationships. METHODS: ESRD from 1977 through 2014 was identified through linkage with Medicare data. ESRD incidence in the cohort compared to the US population was evaluated using life table analyses. Associations of all ESRD, systemic ESRD, hypertensive ESRD, and diabetic ESRD with exposure surrogates (exposed days, fire runs, and fire hours) were examined in Cox proportional hazards models adjusted for attained age (the time scale), race, birth date, fire department, and employment duration. RESULTS: The incidence of all ESRD was less than expected (standardized incidence ratio (SIR) = 0.79; 95% confidence interval = 0.69-0.89, observed = 247). SIRs for ESRD types were not significantly increased. Positive associations of all ESRD, systemic ESRD, and hypertensive ESRD with exposed days were observed: however, 95% confidence intervals included one. CONCLUSIONS: We found little evidence of increased risk of ESRD among this cohort of firefighters. Limitations included the inability to evaluate exposure-response relationships for some ESRD types due to small observed numbers, the limitations of the surrogates of exposure, and the lack of information on more sensitive outcome measures for potential kidney effects.

Mortality in a cohort of US firefighters from San Francisco, Chicago and Philadelphia: an update.

OBJECTIVES: To update the mortality experience of a previously studied cohort of 29 992 US urban career firefighters compared with the US general population and examine exposure-response relationships within the cohort. METHODS: Vital status was updated through 2016 adding 7 years of follow-up. Cohort mortality compared with the US population was evaluated via life table analyses. Full risk-sets, matched on attained age, race, birthdate and fire department were created and analysed using the Cox proportional hazards regression to examine exposure-response associations between select mortality outcomes and exposure surrogates (exposed-days, fire-runs and fire-hours). Models were adjusted for a potential bias from healthy worker survivor effects by including a categorical variable for employment duration. RESULTS: Compared with the US population, mortality from all cancers, mesothelioma, non-Hodgkin's lymphoma (NHL) and cancers of the oesophagus, intestine, rectum, lung and kidney were modestly elevated. Positive exposure-response relationships were observed for deaths from lung cancer, leukaemia and chronic obstructive pulmonary disease (COPD). CONCLUSIONS: This update confirms previous findings of excess mortality from all cancers and several site-specific cancers as well as positive exposure-response relations for lung cancer and leukaemia. New findings include excess NHL mortality compared with the general population and a positive exposure-response relationship for COPD. However, there was no evidence of an association between any quantitative exposure measure and NHL.

Exposure-response relationships for select cancer and non-cancer health outcomes in a cohort of U.S. firefighters from San Francisco, Chicago and Philadelphia (1950-2009).

OBJECTIVES: To examine exposure-response relationships between surrogates of firefighting exposure and select outcomes among previously studied US career firefighters. METHODS: Eight cancer and four non-cancer outcomes were examined using conditional logistic regression. Incidence density sampling was used to match each case to 200 controls on attained age. Days accrued in firefighting assignments (exposed-days), run totals (fire-runs) and run times (fire-hours) were used as exposure surrogates. HRs comparing 75th and 25th centiles of lagged cumulative exposures were calculated using loglinear, linear, log-quadratic, power and restricted cubic spline general relative risk models. Piecewise constant models were used to examine risk differences by time since exposure, age at exposure and calendar period. RESULTS: Among 19,309 male firefighters eligible for the study, there were 1333 cancer deaths and 2609 cancer incidence cases. Significant positive associations between fire-hours and lung cancer mortality and incidence were evident. A similar relation between leukaemia mortality and fire-runs was also found. The lung cancer associations were nearly linear in cumulative exposure, while the association with leukaemia mortality was attenuated at higher exposure levels and greater for recent exposures. Significant negative associations were evident for the exposure surrogates and colorectal and prostate cancers, suggesting a healthy worker survivor effect possibly enhanced by medical screening. CONCLUSIONS: Lung cancer and leukaemia mortality risks were modestly increasing with firefighter exposures. These findings add to evidence of a causal association between firefighting and cancer. Nevertheless, small effects merit cautious interpretation. We plan to continue to follow the occurrence of disease and injury in this cohort.

Chromium VI and stomach cancer: a meta-analysis of the current epidemiological evidence.

OBJECTIVES: Chromium VI (hexavalent chromium, Cr(VI)) is an established cause of lung cancer, but its association with gastrointestinal cancer is less clear. The goal of this study was to examine whether the current human epidemiological research on occupationally inhaled Cr(VI) supports the hypothesis that Cr(VI) is associated with human stomach cancer. METHODS: Following a thorough literature search and review of individual studies, we used meta-analysis to summarise the current epidemiological literature on inhaled Cr(VI) and stomach cancer, explore major sources of heterogeneity, and assess other elements of causal inference. RESULTS: We identified 56 cohort and case-control studies and 74 individual relative risk (RR) estimates on stomach cancer and Cr(VI) exposure or work in an occupation associated with high Cr(VI) exposure including chromium production, chrome plating, leather work and work with Portland cement. The summary RR for all studies combined was 1.27 (95% CI 1.18 to 1.38). In analyses limited to only those studies identifying increased risks of lung cancer, the summary RR for stomach cancer was higher (RR=1.41, 95% CI 1.18 to 1.69). CONCLUSIONS: Overall, these results suggest that Cr(VI) is a stomach carcinogen in humans, which is consistent with the tumour results reported in rodent studies.

Mortality and cancer incidence in a pooled cohort of US firefighters from San Francisco, Chicago and Philadelphia (1950-2009).

OBJECTIVES: To examine mortality patterns and cancer incidence in a pooled cohort of 29 993 US career firefighters employed since 1950 and followed through 2009. METHODS: Mortality and cancer incidence were evaluated by life table methods with the US population referent. Standardised mortality (SMR) and incidence (SIR) ratios were determined for 92 causes of death and 41 cancer incidence groupings. Analyses focused on 15 outcomes of a priori interest. Sensitivity analyses were conducted to examine the potential for significant bias. RESULTS: Person-years at risk totalled 858 938 and 403 152 for mortality and incidence analyses, respectively. All-cause mortality was at expectation (SMR=0.99, 95% CI 0.97 to 1.01, n=12 028). There was excess cancer mortality (SMR=1.14, 95% CI 1.10 to 1.18, n=3285) and incidence (SIR=1.09, 95% CI 1.06 to 1.12, n=4461) comprised mainly of digestive (SMR=1.26, 95% CI 1.18 to 1.34, n=928; SIR=1.17, 95% CI 1.10 to 1.25, n=930) and respiratory (SMR=1.10, 95% CI 1.04 to 1.17, n=1096; SIR=1.16, 95% CI 1.08 to 1.24, n=813) cancers. Consistent with previous reports, modest elevations were observed in several solid cancers; however, evidence of excess lymphatic or haematopoietic cancers was lacking. This study is the first to report excess malignant mesothelioma (SMR=2.00, 95% CI 1.03 to 3.49, n=12; SIR=2.29, 95% CI 1.60 to 3.19, n=35) among US firefighters. Results appeared robust under differing assumptions and analytic techniques. CONCLUSIONS: Our results provide evidence of a relation between firefighting and cancer. The new finding of excess malignant mesothelioma is noteworthy, given that asbestos exposure is a known hazard of firefighting.

Cancer mortality in a Chinese population exposed to hexavalent chromium in drinking water.

BACKGROUND: In 1987, investigators in Liaoning Province, China, reported that mortality rates for all cancer, stomach cancer, and lung cancer in 1970-1978 were higher in villages with hexavalent chromium (Cr+6)-contaminated drinking water than in the general population. The investigators reported rates, but did not report statistical measures of association or precision. METHODS: Using reports and other communications from investigators at the local Jinzhou Health and Anti-Epidemic Station, we obtained data on Cr+6 contamination of groundwater and cancer mortality in 9 study regions near a ferrochromium factory. We estimated: (1) person-years at risk in the study regions, based on census and population growth rate data, (2) mortality counts, based on estimated person-years at risk and previously reported mortality rates, and (3) rate ratios and 95% confidence intervals. RESULTS: The all-cancer mortality rate in the combined 5 study regions with Cr+6-contaminated water was negligibly elevated in comparison with the rate in the 4 combined study regions without contaminated water (rate ratio = 1.13; 95% confidence interval = 0.86-1.46), but was somewhat more elevated in comparison with the whole province (1.23; 0.97-1.53). Stomach cancer mortality in the regions with contaminated water was more substantially elevated in comparison with the regions without contaminated water (1.82; 1.11-2.91) and the whole province (1.69; 1.12-2.44). Lung cancer mortality was slightly elevated in comparison with the unexposed study regions (1.15; 0.62-2.07), and more strongly elevated in comparison with the whole province (1.78; 1.03-2.87). Mortality from other cancers combined was not elevated in comparison with either the unexposed study regions (0.86; 0.53-1.36) or the whole province (0.92; 0.58-1.38). CONCLUSIONS: While these data are limited, they are consistent with increased stomach cancer risk in a population exposed to Crz=6 in drinking water.

Proportionate mortality among current and former members of the United Farm Workers of America, AFL-CIO, in California 1973-2000.

CONTEXT: To further investigate mortality among farm workers, a proportionate mortality ratio (PMR) analysis was conducted among the membership of the United Farm Workers of America (UFW), a farm worker labor union, for the years 1973-2000 in the state of California. PURPOSE: This report compares proportionate mortality for 118 causes of death in the UFW and the general United States population, adjusting for age, sex, race and calendar year of death. In addition, an exploratory analysis was conducted comparing deaths in the UFW to deaths in the California Hispanic population. METHODS: A roster of members of the UFW was compared to the death certificate master files of the state of California for the years 1973 to 2000. Matches were detected using automated techniques and visual review. PMR and associated confidence intervals were calculated using the National Institute for Occupational Safety and Health Life Table Analysis System using deaths in the U.S. as the standard. A similar analysis was conducted limiting attention to the time period 1988-2000 and using deaths in the California Hispanic population as the standard. FINDINGS: There were a total of 139,662 members of the union included in the linkage that yielded 3,977 deaths in the time period 1973-2000. Proportionate mortality in the farm workers was significantly elevated for respiratory tuberculosis, malignant neoplasms of the stomach, biliary passages, liver and gallbladder, and uterine cervix, diabetes mellitus, cerebrovascular disease, cirrhosis of the liver, and "other diseases of the digestive system." Transportation injuries including motor vehicles deaths, deaths from machine injuries, unintentional poisonings and assault and homicide were significantly elevated as well. Farm workers were at significantly lower risk of death from HIV-related disease, malignant neoplasms of the esophagus, intestine, pancreas, lung, urinary bladder, melanoma, and brain, all cancer deaths, "other diseases of the nervous system," ischemic heart disease, conductive disorder, "other diseases of the heart," emphysema, "other respiratory diseases," and symptoms and ill-defined conditions. These results were similar when using California Hispanic deaths as the standard for the years 1988-2000. There was still excess proportionate mortality from tuberculosis, cerebrovascular disease and unintentional injuries among the UFW members and lowered mortality from HIV related deaths, all cancer deaths combined and diseases of the heart. CONCLUSIONS: These results include some unique findings in regard to both excess and deficits of mortality that may be explained by the Hispanic ethnicity and recent immigration of the cohort.

Factors associated with time to availability for cases reported to population-based cancer registries.

OBJECTIVE: Population-based cancer registries provide an excellent source of data for cancer surveillance and research. However, delays in reporting and processing can affect the accuracy of incidence rates and the availability of cases for research. This study was designed to describe factors related to delays in availability of cancer cases for epidemiologic analysis. METHODS: We identified all cancer cases diagnosed in 2000 and reported to the California Cancer Registry by August 2004. We analyzed factors associated with time to availability, defined as the time from diagnosis until the time the case was available for research. RESULTS: A total of 137,270 cancer cases were reported during the study period. The median time to availability for all cases was 382 days. Forty-five percent of cases were available within the first 12 months and 96% were available within 24 months after diagnosis. Cases reported by hospitals had the shortest time to availability (373 days) followed by doctors' offices and laboratories. Melanoma and prostate cancers had longer times to be available than other types of cancer. Time to availability varied by geographic region, but differences by age, gender, race and stage at diagnosis were minimal or non-significant. CONCLUSION: Strategies are needed to improve timeliness without sacrificing quality and completeness.

Agricultural injury in California migrant Hispanic farm workers.

BACKGROUND: Agriculture is among the most hazardous industries in the United States. METHODS: A longitudinal study of injury among migrant Hispanic farm workers residing in six Northern California Migrant Family Housing Centers (MHCs) during the 1997 harvest season was conducted. Participants completed an initial interviewer-administered work-and-health questionnaire at the beginning of the harvest season addressing the preceding year; there were three periodic follow-up surveys. RESULTS: There were 1,201 adult farm workers (participation 85.2%) who completed the initial questionnaire. Of these, 837 (69.7%) completed the final follow-up survey. There were 86 agricultural injuries (incidence 9.3/100 full-time equivalent employees (FTEs), 95% CI 7.5-11.5/100 FTE). Increased risk for agricultural injury occurred among women paid piece-rate (RR 4.9, 95% CI 1.8-12.8). Sprains and strains were most common (31%), followed by lacerations (12%). CONCLUSIONS: Agricultural injury experience in this cohort is comparable to that of agricultural workers in other U.S. settings. Increased risk among women paid piece-rate suggests further study and potential policy changes regarding payment regimens. Heterogeneity of injury in this population presents a major prevention challenge. In view of high frequency of strain and sprain injuries, ergonomic interventions deserve further study.

Injury risks in children of California migrant Hispanic farm worker families.

BACKGROUND: Few data are available addressing occupational and other injury risks among children of migrant Hispanic farm workers. METHODS: We conducted the U.C. Davis Farm Worker Injury Study (UCD-FWIS), a longitudinal follow-up study of injury among migrant Hispanic farm worker families living in six Northern California Migrant Housing Centers (MHCs). Nine hundred forty-one children (age < 18 years) were interviewed through parental proxy. RESULTS: Fifty-one injuries resulting in medical care or at least one-half day of lost or restricted work or school time occurred among 49 children (3.8 injuries/100 person-years). Open wounds (31.4%) and fractures (29.4%) were most common. Falls comprised over one-third of the cases, followed by being struck and bicycle injuries. Over three-quarters of subjects never use a helmet when riding a bicycle. Seventy-eight (8.3%) children reported employment in the preceding year, typically involving manual agricultural tasks. Two injury cases were occupational and involved agricultural work. CONCLUSIONS: Occupational injury was uncommon in this group of children in migrant Hispanic farm worker families. Injury prevention in this population should include a focus on the home and surrounding environment as well as the work place.