Arsenic levels in drinking water and mortality of liver cancer in Taiwan.

The carcinogenic effect of arsenic is well documented, but epidemiologic data on liver cancer were limited. To evaluate the dose-response relationship between arsenic in drinking water and mortality of liver cancer, we conducted a study in 138 villages in the southwest coast area of Taiwan. We assessed arsenic levels in drinking water using data from a survey conducted by the government and reviewed death certificates from 1971 to 1990 to identify liver cancer cases. Using village as the unit, we conducted multi-variate regression analyses and then performed post hoc analyses to validate the findings. During the 20-year period, 802 male and 301 female mortality cases of liver cancer were identified. After adjusting for age, arsenic levels above 0.64 mg/L were associated with an increase in the liver cancer mortality in both genders, but no significant effect was observed for lower exposure categories. Post hoc analyses and a review of literature supported these findings. We concluded that exposures to high arsenic levels in drinking water are associated with the occurrence of liver cancer, but such an effect is not prominent at exposure levels lower than 0.64 mg/L.

A positive relationship between ambient temperature and bipolar disorder identified using a national cohort of psychiatric inpatients.

OBJECTIVE: This study characterizes the positive relationship between daily temperature and bipolar disorder in a cohort of Taiwanese psychiatric inpatients. METHODS: Meteorological data, provided by the Central Weather Bureau (CWB) of Taiwan, were interpolated to create representative estimates of mean diurnal temperatures for 352 townships. Psychiatric inpatient admissions enrolled in the national health-care insurance system were retrieved from the 1996-2007 Psychiatric Inpatient Medical Claim (PIMC) dataset. The generalized linear mixed models with Poisson distribution were used to evaluate the relative risks of mean diurnal temperature with respect to increased admissions for bipolar disorder, while adjusting for internal correlations and demographic covariates. RESULTS: Increased relative risks of bipolar disorder admissions were associated with the increasing trends of temperature over 24.0 °C (50th ‰), especially for adults and females. The highest daily diurnal temperatures above 30.7 °C (99th ‰) had the greatest risks of bipolar hospitalizations. CONCLUSION: Understanding the increase of bipolar disorder admissions occurring in extreme heat is important in the preparation and prevention of massive recurrences of bipolar episodes.

Relationship between heat index and mortality of 6 major cities in Taiwan.

Increased mortality, linked to events of extreme high temperatures, is recognized as one critical challenge to the public health sector. Therefore, this ecological study was conducted to assess whether this association is also significant in Taiwan and the characteristics of the relationship. Daily mean heat indices, from 1994 through 2008, were used as the predictor for the risk of increased mortality in populations from 6 major Taiwanese cities. Daily mortality data from 1994 through 2008 were retrieved from the Taiwan Death Registry, Department of Health, Taiwan, and meteorological data were acquired from the Central Weather Bureau. Poisson regression analyses using generalized linear models were applied to estimate the temperature-mortality relationship. Daily mean heat indices were calculated and used as the temperature metric. Overall, increased risk ratios in mortality were associated with increased daily mean heat indices. Significantly increased risk ratios of daily mortality were evident when daily mean heat indices were at and above the 95th percentile, when compared to the lowest percentile, in all cities. These risks tended to increase similarly among those aged 65 years and older; a phenomenon seen in the cities of Keelung, Taipei, Taichung, Tainan, and Kaohsiung, but not Chiayi. Being more vulnerable to heat stress is likely restricted to a short-term effect, as suggested by lag models which showed that there was dominantly an association during the period of 0 to 3 days. In Taiwan, predicting city-specific daily mean heat indices may provide a useful early warning system for increased mortality risk, especially for the elderly. Regional differences in health vulnerabilities should be further examined in relation to the differential social-ecological systems that affect them.

Increased serum level of epidermal growth factor receptor in liver cancer patients and its association with exposure to arsenic.

Arsenic is a human carcinogen and can activate epidermal growth factor receptor (EGFR) in human cell lines. As EGFR is associated with the occurrence of cancers, we conducted a study to evaluate whether serum EGFR may increase in liver cancer patients, particularly in those with exposure to arsenic. We recruited 100 patients of liver cancer and 100 age- and sex-matched controls in Taiwan and determined EGFR levels in sera by enzyme-linked immunosorbent assay. The patients had higher EGFR levels (668.1 vs. 243.1 fmol/mL, p<0.01), and after adjusting for hepatitis B and C, they still had an average EGFR level 406.1 fmol/mL higher than that of the controls (p<0.01). When we compared 22 patients residing in an endemic area of arsenic intoxication to 22 age- and sex-matched patients residing outside the area, we found that patients from the endemic area had higher EGFR levels (882.8 vs. 511.6 fmol/mL, p = 0.04). We concluded that EGFR is over-expressed in patients of liver cancer, particularly in those with exposure to arsenic, and therefore, serum EGFR level is not only a potential biomarker of liver cancer, but also a potential biomarker of cancers associated with arsenic exposure.

Relationship between mean daily ambient temperature range and hospital admissions for schizophrenia: Results from a national cohort of psychiatric inpatients.

Environmental temperature is known to correlate with schizophrenia, but little is known about the association with changes in temperature. This 12-year study aimed to evaluate the relationship between the mean daily range of ambient temperature and schizophrenia admissions in a national cohort of psychiatric inpatients in Taiwan. Meteorological data provided by the Central Weather Bureau of Taiwan were interpolated to create representative estimates. Psychiatric inpatient admissions in all hospitals with medical services enrolled in the current health care insurance system were retrieved from the 1996-2007 Psychiatric Inpatient Medical Claim dataset of the National Health Insurance Research Database. Generalized linear models with Poisson distributions were used to analyze the impact of mean diurnal change of temperature on schizophrenia admissions, controlling for internal correlations and demographic covariates. The daily temperature range varied between 1.7°C and 12.1°C (1st to 99th percentile). The relative risk of schizophrenia admission was significantly increased at a temperature range of 3.2°C (10th percentile), and the maximum was at 12.1°C (99th percentile); however, no such association was found with schizoaffective disorder. When restricted to the capital and largest city, the effects of temperature range were prominent and may correlate with temperature itself. The joint effect of temperature and temperature range was associated with elevated risk, particularly at cooler temperatures. A positive correlation was found between increasing temperature range and schizophrenia admissions. The increase in morbidity at high percentiles suggests that the increasing dynamics of temperature range are a valid reflection of risk, highlighting the need for precautionary action.

Increased risks of infant mortality and of deaths due to congenital malformation in the offspring of male electronics workers.

BACKGROUND: There is limited evidence on the association between paternal occupational exposure during preconception and infant mortality and deaths due to congenital malformation. This retrospective cohort study was conducted to determine if such an association existed among male workers employed in an electronics factory. METHODS: We linked the databases of labor insurance, birth registration, and national death registry, identified 7,202 male workers ever employed in this factory with 13,592 liveborn children and 81 deaths in the first year after, excluding 861 children with potential maternal exposure from the same workplace. Fathers employed in this factory during their preconceptional periods (3 months prior to the conception) were considered as exposed compared with those not employed during the same periods. Poisson regression models were constructed to adjust for potential confounding by child's sex, parity, multiple births, year of birth, parental age at delivery, and educational levels. RESULTS: Based on 24 exposed cases, the rate ratios (RRs) of infant mortality were increased to 5.06 (95% CI: 2.33-11.00) and 2.81 (95% CI: 1.44-5.51) among liveborn children whose fathers worked for >10 and 1-10 years, respectively, in this factory during preconception. Maternal delivery age less than 20 years, fathers with less than 10 years of education, and multiple births were associated with increased risks of infant mortality. When limited to 28 deaths with congenital malformation, Poisson regression model showed an increased risk for exposed pregnancies (RR = 3.75; 95% CI: 1.29-10.94), especially among cardiac defects (RR = 5.06; 95% CI: 1.58-16.19). CONCLUSIONS: Our study suggests that paternal occupational exposures, possibly to organic solvents during preconception, might increase infant mortality and deaths due to congenital malformation, especially for cardiac defects. However, the small numbers of this study limited the generalization of its findings.

Increased risk of cancer in the offspring of female electronics workers.

There is limited evidence on the hypothesis that maternal occupational exposure near conception increases the risk of cancer in offspring. This study is to investigate whether women employed in an electronics factory increases childhood cancer among first live born singletons. We linked the databases of Birth Registration and Labor Insurance, and National Cancer Registry, which identified 40,647 female workers ever employed in this factory who gave 40,647 first live born singletons, and 47 of them developed cancers during 1979-2001. Mothers employed in this factory during their periconceptional periods (3 months before and after conception) were considered as exposed and compared with those not employed during the same periods. Poisson regression model was constructed to adjust for potential confounding by maternal age, education, sex, and year of birth. Based on 11 exposed cases, the rate ratio of all malignant neoplasms was increased to 2.26 [95% confidence interval (CI), 1.12-4.54] among children whose mothers worked in this factory during periconceptional periods. The RRs were associated with 6 years or less (RR=3.05; 95% CI, 1.20-7.74) and 7-9 years (RR=2.49; 95% CI, 1.26-4.94) of education compared with 10 years or more. An increased association was also found between childhood leukemia and exposed pregnancies (RR=3.83; 95% CI, 1.17-12.55). Our study suggests that maternal occupation with potential exposure to organic solvents during periconception might increase risks of childhood cancers, especially for leukemia.

Increased standardized incidence ratio of breast cancer in female electronics workers.

BACKGROUND: In 1994, a hazardous waste site, polluted by the dumping of solvents from a former electronics factory, was discovered in Taoyuan, Taiwan. This subsequently emerged as a serious case of contamination through chlorinated hydrocarbons with suspected occupational cancer. The objective of this study was to determine if there was any increased risk of breast cancer among female workers in a 23-year follow-up period. METHODS: A total of 63,982 female workers were retrospectively recruited from the database of the Bureau of Labor Insurance (BLI) covering the period 1973-1997; the data were then linked with data, up to 2001, from the National Cancer Registry at the Taiwanese Department of Health, from which standardized incidence ratios (SIRs) for different types of cancer were calculated as compared to the general population. RESULTS: There were a total of 286 cases of breast cancer, and after adjustment for calendar year and age, the SIR was close to 1. When stratified by the year 1974 (the year in which the regulations on solvent use were promulgated), the SIR of the cohort of workers who were first employed prior to 1974 increased to 1.38 (95% confidence interval, 1.11-1.70). No such trend was discernible for workers employed after 1974. When 10 years of employment was considered, there was a further increase in the SIR for breast cancer, to 1.62. Those workers with breast cancer who were first employed prior to 1974 were employed at a younger age and for a longer period. Previous qualitative studies of interviews with the workers, corroborated by inspection records, showed a short-term high exposure to chlorinated alkanes and alkenes, particularly trichloroethylene before 1974. There were no similar findings on other types of cancer. CONCLUSION: Female workers with exposure to trichloroethylene and/or mixture of solvents, first employed prior to 1974, may have an excess risk of breast cancer.