Arsenic, vinyl chloride, viral hepatitis, and hepatic angiosarcoma: a hospital-based study and review of literature in Taiwan

BACKGROUND

Hepatic angiosarcoma (HAS) is a rare type of liver cancer that is often fatal, and arsenic and vinyl chloride monomer (VCM) are two major causal agents. Whereas Taiwan is an endemic area of liver cancer, epidemiologic data on HAS are limited. We reviewed the cases observed at a teaching hospital to evaluate the roles of VCM, arsenic, and viral hepatitis in the occurrence of HAS.

METHODS

We reviewed the medical records of patients with pathological proof of HAS from January 2000 to August 2010 at a teaching hospital which is adjacent to the major VCM processing area in Taiwan and nearby an endemic area of arsenic exposure from drinking water. We also conducted a literature review and included all patients of HAS reported in Taiwan.

RESULTS

Six male and three female cases aged from 56 to 83 years (64.6 ± 8.2 years) were identified at the hospital. The differences in clinical features between men and women were not statistically significant. None of them had exposure to VCM or arsenic in drinking water. Two had evidence of hepatitis C infection, but none had evidence of hepatitis B infection. Five male and four female cases aged 30 to 82 years (58.6 ± 15.5 years) were identified in the literature, including two with arsenic exposure and one with chronic hepatitis B infection.

CONCLUSIONS

HAS is rare in Taiwan, and we found no evidence supporting a major role of VCM, arsenic in drinking water, or viral hepatitis in its occurrence.

Age adjustment in ecological studies: using a study on arsenic ingestion and bladder cancer as an example

Background

Despite its limitations, ecological study design is widely applied in epidemiology. In most cases, adjustment for age is necessary, but different methods may lead to different conclusions. To compare three methods of age adjustment, a study on the associations between arsenic in drinking water and incidence of bladder cancer in 243 townships in Taiwan was used as an example.

Methods

A total of 3068 cases of bladder cancer, including 2276 men and 792 women, were identified during a ten-year study period in the study townships. Three methods were applied to analyze the same data set on the ten-year study period. The first (Direct Method) applied direct standardization to obtain standardized incidence rate and then used it as the dependent variable in the regression analysis. The second (Indirect Method) applied indirect standardization to obtain standardized incidence ratio and then used it as the dependent variable in the regression analysis instead. The third (Variable Method) used proportions of residents in different age groups as a part of the independent variables in the multiple regression models.

Results

All three methods showed a statistically significant positive association between arsenic exposure above 0.64 mg/L and incidence of bladder cancer in men and women, but different results were observed for the other exposure categories. In addition, the risk estimates obtained by different methods for the same exposure category were all different.

Conclusions

Using an empirical example, the current study confirmed the argument made by other researchers previously that whereas the three different methods of age adjustment may lead to different conclusions, only the third approach can obtain unbiased estimates of the risks. The third method can also generate estimates of the risk associated with each age group, but the other two are unable to evaluate the effects of age directly.

Characteristics of pyogenic liver abscess patients with and without diabetes mellitus

OBJECTIVES

Pyogenic liver abscess (PLA) is relatively common in patients with diabetes mellitus (DM), but it is unclear whether there are differences between patients with and without DM. We conducted a study to identify the possible differences and factors that affect fatality.

METHODS

We included PLA patients treated at a medical center from April 2001 to March 2004 and compared the clinical characteristics of patients with and without DM. We applied chi-square, Fisher's exact, and t-tests to evaluate the differences between the two groups and used logistic regressions to identify predictors of fatality.

RESULTS

Of the 377 patients included, 182 (48.3%) had DM. Patients with DM had higher prevalence rates of cryptogenic etiology, gas-forming nature, thrombocytopenia, hyperglycemia, growth of Klebsiella pneumonia in blood cultures, metastatic infection, and bacteremia, but lower prevalence rates of biliary origin, right upper quadrant pain, and growth of Escherichia coli in pus cultures. Whereas creatinine >1.3 mg/dl (adjusted odds ratio (OR) 7.3, 95% confidence interval (CI) 2.2-24.5) and gas-forming nature (adjusted OR 9.4, 95% CI 3.0-24.5) were predictors of fatality, DM was not. We discovered that C-reactive protein and neutrophil were good biomarkers of PLA, but not asparate aminotransferase and alanine aminotransferase.

CONCLUSIONS

PLA patients with and without DM have different clinical characteristics, but DM is not a predictor of fatality. We have identified several biomarkers that might help reduce the misdiagnosis of PLA.

Associations between arsenic in drinking water and pterygium in southwestern Taiwan

BACKGROUND

Pterygium is a fibrovascular growth of the bulbar conjunctiva and underlying subconjunctival tissue that may cause blindness. The mechanism of pterygium formation is not yet fully understood, but pterygium has some tumorlike features.

OBJECTIVES

The objective of this study was to evaluate the association between arsenic exposure through drinking water and the occurrence of pterygium in southwestern Taiwan.

METHODS

We recruited participants > 40 years of age from three villages in the arseniasis-endemic area in southwestern Taiwan (exposure villages) and four neighboring nonendemic villages (comparison villages). Each participant received an eye examination and a questionnaire interview. Photographs taken of both eyes were later graded by an ophthalmologist to determine pterygium status.

RESULTS

We included 223 participants from the exposure villages and 160 from the comparison villages. The prevalence of pterygium was higher in the exposure villages across all age groups in both sexes and increased with cumulative arsenic exposure. We found a significant association between cumulative arsenic exposure and the prevalence of pterygium. After adjusting for age, sex, working under sunlight, and working in sandy environments, we found that cumulative arsenic exposure of 0.1-15.0 mg/L-year and > or = 15.1 mg/L-year were associated with increased risks of developing pterygium. The adjusted odds ratios were 2.04 [95% confidence interval (CI), 1.04-3.99] and 2.88 (95% CI, 1.42-5.83), respectively.

CONCLUSIONS

Chronic exposure to arsenic in drinking water was related to the occurrence of pterygium, and the association was still observed after adjusting for exposures to sunlight and sandy environments.

Water disinfection by-products and the risk of specific birth defects: a population-based cross-sectional study in Taiwan

BACKGROUND

Recent findings suggest that exposure to disinfection by-products may increase the risk of birth defects. Previous studies have focused mainly on birth defects in general or groups of defects. The objective of the present study was to assess the effect of water disinfection by-products on the risk of most common specific birth defects.

METHODS

We conducted a population-based cross-sectional study of 396,049 Taiwanese births in 2001-2003 using information from the Birth Registry and Waterworks Registry. We compared the risk of eleven most common specific defects in four disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs) representing high (TTHMs 20+ microg/L), medium (TTHMs 10-19 microg/L), low exposure (TTHMs 5-9 microg/L), and 0-4 microg/L as the reference category. In addition, we conducted a meta-analysis of the results from the present and previous studies focusing on the same birth defects.

RESULTS

In multivariate logistic regression analysis the risk of ventricular septal defects (adjusted odds ratio 1.81, 95% confidence interval: 0.98 3.35), cleft palate (1.56. 95% CI: 1.00, 2.41), and anencephalus (1.96, 95% CI: 0.94, 4.07) were elevated in the high exposure compared to the reference category. In the meta-analysis, the summary odds ratio for ventricular septal defects (1.59, 95% CI: 1.21, 2.07) was consistently elevated.

CONCLUSION

The present study suggests that prenatal exposure to disinfection by-products increases the risk of ventricular septal defects, cleft palate, and anencephalus. The evidence on ventricular septal defects is consistent in the three available studies.

Staurosporine modulates radiosensitivity and radiation-induced apoptosis in U937 cells

PURPOSE

The present study aims at investigating the involvement of several genes in the cell cycle distribution and apoptosis in U937 cells, a cell line lacking functional p53 protein, after combined treatment with staurosporine and irradiation.

MATERIALS AND METHODS

Using a DNA fragmentation assay, flow cytometry and western blot analysis, the molecular basis for the effects of staurosporine in combination with the irradiation of leukemia cells was investigated.

RESULTS

Our results indicated that combined treatment led to an increased apoptotic cell death in U937 cells, which is correlated with the phosphorylation of the V-Jun sarcoma virus 17 oncogene homolog (c-JUN) NH(2)-terminal kinase protein (JNK), the activation of caspases, the increase in B cell leukemia/lymphoma 2 (Bcl-2) associated X protein (Bax), the decrease in Bcl xL protein (Bcl-XL) levels, the loss of mitochondria membrane potential and the release of cytochrome c.

CONCLUSIONS

Abrogation of the G2 checkpoint should be an effective strategy against p53-deficient leukemia cells to irradiation-induced cell killing.

Arsenic level in drinking water and mortality of lung cancer (Taiwan)

OBJECTIVE

Lung cancers have been observed among patients of arsenic intoxication since the 1950s, but data on the dose-response relationship were limited. In order to obtain such data, a study was conducted in ten townships in Taiwan.

METHODS

Measurements of arsenic levels in drinking water were available for 138 villages from a census survey conducted by the government. Certificates of deaths that occurred in the villages between January 1, 1971 and December 31, 1990 were reviewed, and 673 male and 405 female mortality cases of lung cancer were identified. Multi-variate regression models were applied to assess associations between arsenic levels in drinking water and mortality of lung cancer using village as the unit.

RESULTS

After adjusting for age, arsenic levels above 0.64 mg/l were associated with a significant increase in the mortality of lung cancer in both genders, but no significant effect was observed at lower levels. Post-hoc analyses confirmed such a dose-response relationship.

CONCLUSIONS

The results indicate a prominent carcinogenic effect of high arsenic levels in drinking water on the lung and suggest the new 'maximum contaminant level' of 10 micro g/l published by the US Environmental Protection Agency provides sufficient protection against lung cancer. Nonetheless, further studies with exposure data on individuals are warranted to confirm these findings.

Prevalence of musculoskeletal disorder among workers in Taiwan: a nationwide study

Musculoskeletal disorder (MSD) is a common problem among workers. In spite of the numerous reports on MSD in various specific groups of workers, few data on the prevalence in the general working population are available except for back pain. We analyzed the information collected through a nationwide survey in Taiwan in 1994 to estimate the prevalence of MSD by age, gender, and education level and identify high-risk industries. In the survey, a standard questionnaire was distributed to a representative sample of 22,475 non-self-employed workers in Taiwan. National estimates were obtained by applying a weight to each participant. Among the sampled workers, 18,942 (84.3%) participated, and 37.0% (standard error=0.4%) had MSD. Female workers had a significantly higher overall prevalence than male workers (39.5% vs. 35.2%, p<0.05). Education and age also had significant associations with MSD (p<0.001 in both genders). "Lower back and waist" were the most frequently affected body parts (18.3% among males and 19.7% among females), but the prevalence of MSDs of the neck, shoulders, hands and wrists were also above 10%. The top ten high-risk major industries for MSD of various body parts for each gender were identified, and some industries, including "Basic Metal Industries" and "Buildings Construction," were among the top ten for multiple body parts. Our study showed that MSDs of body parts other than the back are also prevalent, especially in the neck, shoulders, hands and wrists. We also identified high-risk industries for further research and intervention.

Cell type specificity of lung cancer associated with arsenic ingestion

Arsenic is a well-documented human carcinogen. Previous studies on urinary bladder and skin cancers have shown that arsenic can cause specific cell types of malignancy. To evaluate whether this is also true for lung cancers, we conducted a study on 243 townships in Taiwan. We identified patients through the National Cancer Registry Program and compared the proportion of each major cell type between an endemic area of arsenic intoxication with exposures through drinking water, which includes 5 of the townships and the other 238 townships. To control for gender and age, we analyzed data on men and women separately and divided patients into four age groups. A total of 37,290 lung cancer patients, including 26,850 men and 10,440 women, was diagnosed between January 1, 1980 and December 31, 1999 in study townships. Patients from the endemic area had higher proportions of squamous cell and small cell carcinomas, but a lower proportion of adenocarcinomas. These findings were similar across all age groups in both genders, although the lack of data on smoking is a limitation of our study. The results suggested that the carcinogenicity of arsenic on lungs is also cell type-specific: squamous cell and small cell carcinomas appeared to be related to arsenic ingestion, but not adenocarcinoma. Whereas data in the literature are limited, the association between adenocarcinoma and arsenic exposures through inhalation appeared to be stronger than that of squamous cell carcinoma. Therefore, we speculate that arsenic may give rise to different mechanisms in the development of lung cancers through different exposure routes.

The lack of a specific association between arsenic in drinking water and hepatocellular carcinoma

BACKGROUND/AIMS

Liver cancers, particularly angiosarcomas, among patients with arsenic intoxication have been reported for more than half a century. Studies on cancers of urinary system and skin showed the carcinogenic effect of arsenic was cell-type specific. To evaluate whether this is also true for liver cancers, a study was conducted in 243 townships in Taiwan.

METHODS

Cases of liver cancer were identified through the National Cancer Registry Program. The distribution of major cell-types was compared between an endemic area of arsenic intoxication, including 5 of the 243 townships, and the rest of the townships.

RESULTS

A total of 40,832 patients with liver cancer, including 32,034 men and 8798 women, were diagnosed between January 1, 1980 and December 31, 1999 in the study townships. Distributions of the two major cell-types, hepatocellular carcinoma and cholangiocarcinoma, did not appear to be different between the arsenic intoxication endemic area and the other areas. The rest of the cell-types did not have enough cases to provide stable estimates.

CONCLUSIONS

Convincing evidence in the literature has suggested a specific association between angiosarcoma of liver and arsenic ingestion, but the current study did not find such an association for hepatocellular carcinoma, although it is the major cell-type.

Working hours spent on repeated activities and prevalence of back pain

BACKGROUND AND AIMS

Back pain is the most common reason for filing workers' compensation claims in the United States and affects large numbers of workers in many other countries. To evaluate the associations between working hours spent on repeated activities and back pain, data gathered through the 1988 National Health Interview Survey were analysed. The data were also used to identify high risk occupations.

METHODS

A total of 30 074 workers participated in the survey. They were asked to provide information on their job, including the time spent on repeated strenuous physical activities (RSPA) and the time spent on repeated bending, twisting, or reaching (RBTR) on a typical job. A case of back pain was defined as a worker who had back pain every day for a week or more during the past 12 months. Each case was asked to report the cause of back pain. Those who attributed their back pain to repeated activities (RA) or a single accident or injury (AI) were asked to recall whether they performed RA or had the AI at work.

RESULTS

Whereas the prevalence of back pain increased as the number of working hours spent on RSPA or RBTR increased, the dose-response relations were not linear for either factor, suggesting the involvement of other unmeasured factors. The estimated overall prevalence of RA back pain was 8.9% among male workers and 5.9% among female workers. "Carpenters" had the highest prevalence (19.2%) and most cases (338 000) among the major occupations of men, and "nursing aides, orderlies, and attendants" had the highest prevalence (15.2%) and most cases (217 000) among the major occupations of women.

CONCLUSIONS

The number of hours spent on repeated activities at work was associated with the prevalence of back pain. This study identified high risk occupations for future research and intervention.

Cancer risk assessment for arsenic exposure through oyster consumption

Risk is assessed on the basis of assumptions, but this practice might not be well received by the general public. To avoid miscommunication, the assumptions should be stated clearly in reporting the results. Recently, a report on an assessment of the cancer risk associated with consumption of oysters caused a panic among consumers in Taiwan and produced significant effects on related industries. A group of researchers measured the arsenic content in oysters in the Taiwan area and conducted a cancer risk assessment accordingly. The results, published in a research article in an international journal, included a lifetime cancer risk estimate of 5.10/10(-4) as calculated based on the assumption that a person consumes oysters with the highest arsenic level (19.3 mg/g dry weight) at the highest rate (139 g/day) for 30 years. A national newspaper in Taiwan translated part of the article and published results that focused on the finding that this estimate was more than 500 times higher than what would be considered acceptable by the U.S. Environmental Protection Agency. As a result, most consumers stopped purchasing oysters, and the related industries suffered substantial losses. The newspaper's omission of the key assumptions in the risk assessment and the extreme assumptions made in the risk assessment led to this tragedy. This event demonstrated the importance of careful communication of risk assessment results.

Arsenic in drinking water and skin cancers: cell-type specificity (Taiwan, ROC)

OBJECTIVE

The association between arsenic ingestion and cancer has been documented for more than a century. Previous studies showed that the carcinogenic effects of arsenic on the urinary system are cell-type specific. To evaluate whether this is also true for skin cancers, we conducted an ecological study in 243 townships in Taiwan.

METHODS

The arsenic exposure was assessed on the basis of measurement reports from a previous survey, and cases of skin cancer were identified using the information gathered by the National Cancer Registry Program. We analyzed the data by regression models using multiple variables to describe the exposure status, and an urbanization index was also included in the models to adjust for the effects of urbanization.

RESULTS

A total of 2369 patients with skin cancer, comprising 1415 men and 954 women, were registered between 1 January 1980 and 31 December 1989. Among the three major cell types of skin cancer, squamous cell carcinoma and basal cell carcinoma appear to be associated with ingestion of arsenic. Such an association was not observed for malignant melanoma.

CONCLUSIONS

The results suggested that the carcinogenicity of arsenic on skin is cell-type specific, which is compatible with the findings in previous studies on urinary cancers.

Back pain prevalence in US industry and estimates of lost workdays

OBJECTIVES

Back pain is the most common reason for filing workers' compensation claims and often causes lost workdays. Data from the 1988 National Health Interview Survey were analyzed to identify high-risk industries and to estimate the prevalence of work-related back pain and number of workdays lost.

METHODS

Analyses included 30074 respondents who worked during the 12 months before the interview. A case patient was defined as a respondent who had back pain every day for a week or more during that period.

RESULTS

The prevalence of lost-workday back pain was 4.6%, and individuals with work-related cases lost 101.8 million workdays owing to back pain. Male and female case patients lost about the same number of workdays. Industries in high-risk categories were also identified for future research and intervention, including those seldom studied.

CONCLUSIONS

This study provides statistically reliable national estimates of the prevalence of back pain among workers and the enormous effect of this condition on American industry in terms of lost workdays.