Increased chromosome-type chromosome aberration frequencies as biomarkers of cancer risk in a blackfoot endemic area.

To examine whether biomarkers such as sister chromatid exchanges (SCEs) and chromosome aberrations (CAs) can predict cancer development, a nested case-control study was performed in a blackfoot endemic area with a known high cancer risk. A cohort of 686 residents was recruited from three villages in the blackfoot endemic area. Personal characteristics were collected, and venous blood was drawn for lymphocyte culture and stored in a refrigerator. The vital status and cancer development were followed using the National Death Registry, Cancer Registry, and Blackfoot Disease Registry. The follow-up period was from August 1991 to July 1995. During this 4-year period, 31 residents developed various types of cancer. Blood culture samples from nine of these subjects were unsuitable for experiments due to improper storage. Finally, a total of 22 cancer cases had cytogenetic samples that could be analyzed. Twenty-two control subjects were selected from those who did not develop cancer in the study period, and these subjects were matched to cases by sex, age, smoking habits, and residential area. The results showed that there was no significant difference in the frequencies of SCE and chromatid-type CAs between the case and control groups. However, the frequencies of chromosome-type CAs, e.g., chromosome-type gaps, chromosome-type breaks, chromosome-type breaks plus exchanges, total chromosome-type aberrations, and total frequencies of CAs in the case group, were significantly higher than those in the control group (P < 0.05). The odds ratio of cancer risk in subjects with more than zero chromosome-type breaks was 5.0 (95% confidence interval = 1.09-22.82) compared to those with zero chromosomal breaks. The odds ratios for more than zero chromosome-type breaks plus exchanges and a frequency of total chromosome-type aberrations of >1.007% were 11.0 and 12.0, respectively (P < 0.05). Subjects with a total CA frequency of >4.023% had a 9-fold increase for cancer risk. These results indicate that chromosome-type CAs are good biomarkers for the prediction of cancer development, whereas SCEs and chromatid-type CAs cannot predict cancer risk.

Relationship between magnesium levels in drinking water and sudden infant death syndrome.

The possible association between the risk of death from sudden infant death syndrome (SIDS) and the levels of magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. Characteristics for all SIDS deaths (501 cases) among Taiwan residents from 1988 through 1997 were compared with those of people who died from other causes (501 controls). The levels of magnesium in the drinking water of these residents were determined from data obtained from the Taiwan Water Supply Corporation (TWSC). The controls were pair-matched to the SIDS cases by sex, month and year of birth. The results of our study show that there is a significant trend towards a decreased risk of SIDS with increasing magnesium levels in drinking water.

Association between chlorination of drinking water and adverse pregnancy outcome in Taiwan.

Chlorination has been the major means of disinfecting drinking water in Taiwan. The use of chlorinated water has been hypothesized to lead to several adverse birth outcomes, including low birth weight and preterm delivery. We performed a study to examine the relationship between the use of chlorinated water and adverse birth outcomes in Taiwan. The study areas included 14 chlorinating municipalities (CHMs), which were defined as municipalities in which > 90% of the municipal population was served by chlorinated water, and 14 matched nonchlorinating municipalities (NCHMs), defined as municipalities in which < 5% of the municipal population is served by chlorinated water. The CHMs and NCHMs were similar to one another in terms of level of urbanization and sociodemographic characteristics. The study population comprised 18,025 women residing in the 28 municipalities who had a first parity singleton birth between 1 January 1994 and 31 December 1996 and for which complete information on maternal age, education, gestational age, birth weight, and sex of the baby were available. The results of our study suggest that there was no association between consumption of chlorinated drinking water and the risk of low birth weight.

Occupational lead exposure and blood pressure.

BACKGROUND: To assess the relation between occupational lead exposure and elevated blood pressure with consideration of a possible confounding effect by noise exposure. MATERIALS AND METHOD: Some 112 male and 110 female workers at two lead battery manufacturing factories were recruited for this 1992 study in Taiwan. Study participants received regular physical examinations, including standard measurement of blood pressure, body height/weight. Current occupational exposures to lead and noise were measured by a personal sampling scheme and instruments, and included individual ambient lead/noise exposure and blood lead level. RESULTS: Among the 222 battery-factory workers, the average blood lead level was 56.9 +/- 25.5 micrograms/dl (mean +/- standard deviation), the average concentration of ambient lead exposure was 0.190 +/- 0.331 mg/m3, average noise exposure was 85.9 +/- 5.7 dBA, average systolic blood pressure was 125.2 +/- 14.9 mmHg, average diastolic pressure was 80.2 +/- 10.9 mmHg, and average mean arterial pressure was 95.2 +/- 11.1 mmHg. After considering all possible confounding variables, multivariate regression analyses demonstrated that current blood lead level was not a significant predictor for both systolic and diastolic blood pressures in either sex. In the final model, body mass index and years of working in the factory were the only two factors significantly associated with a change in blood pressure. No evidence of an effect of ambient lead exposure or noise exposure on blood pressure were found. CONCLUSIONS: The present study suggests that short-term lead exposure, either ambient lead exposure or blood lead level, was not related to blood pressure change among workers who had been exposed at work to occupational lead. These results add to the body of evidence indicating that blood lead exposure does not adversely affect blood pressure.

Obstructive pulmonary function defects among Taiwanese firebrick workers in a 2-year follow-up study.

The purpose of the study was to follow up an earlier observation of pulmonary function among workers employed in firebrick-manufacturing factories. A 2-year follow-up study of pulmonary function among 442 workers in 30 firebrick-manufacturing factories was designed. Excluding 79 workers with a history of other occupational dust exposure, changes in pulmonary function of 291 firebrick workers were compared with pulmonary function in 72 control subjects over a period of 2 years. Baseline pulmonary function values (i.e., forced expiratory volume in 1 second [FEV1]/forced vital capacity [FVC] and forced expiratory flow after 50% of vital capacity has been expelled [FEF50%] in smoking firebrick workers, and FEV1/FVC and FEF75% in nonsmoking firebrick workers) were significantly lower than those in the comparison group. The statistical method for repeated measurements was used for comparison of the difference between follow-up and baseline lung function. There was no significant difference in FVC and FEV1 changes between firebrick workers and those in the comparison group during the 2-year follow-up period. The decreases in FEV1/FVC, peak expiratory flow rate, maximal midexpiratory flow, and FEF50% in the firebrick workers were significantly greater than in the comparison group, after adjustment for smoking status. The FEV1, maximal midexpiratory flow, FEF50%, and FEF75% also showed a dose-response relationship with job titles. The decrement of pulmonary function in the 2-year follow-up period was the worst in burning work, followed by crushing and molding. The results show that workers in firebrick-manufacturing factories with exposure to silica-containing dusts may contract obstructive pulmonary function defects.

Association between aminolevulinate dehydrogenase genotype and blood lead levels in Taiwan.

This study was designed to evaluate the association between the aminolevulinate dehydrogenase (ALAD) genotype and blood lead levels in a general population environmentally exposed to lead. This study population of 660 subjects was secondarily sampled from the 3000 random samples of Taiwanese general population to study the distribution of blood lead levels in the Taiwanese population. A simple assay based on the polymerase chain reaction-restriction fragment length polymorphism technique was used to determine the genotype of the ALAD gene. This study found that most of the Taiwanese population was ALAD 1-1 (95.4%). Only 4.6% (30 subjects) of population were found to be 1-2 or 2-2. It has been hypothesized that the ALAD2 allele is associated with increased absorption of lead. This study found that individuals with ALAD2 alleles had 20% higher blood lead levels than persons with ALAD1 alleles (7.83 +/- 5.95 vs 6.51 +/- 5.03 micrograms/dL). However, the difference was not statistically significant, even after adjustment for other risk factors of environmental exposure. The result supports the previous finding that individuals with ALAD2 allele had higher blood lead levels. The small sample size and large amount of variation in our study may account for the insignificant association.

Increased risk of preterm delivery in areas with air pollution from a petroleum refinery plant in Taiwan.

The petrochemical and petroleum industries are among the main sources of industrial air pollution in Taiwan. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to a petroleum refinery plant. The prevalence of delivery of preterm birth infants was significantly higher in mothers living in a petroleum refinery area compared to controls in Taiwan. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.41 (95% CI = 1.08-1.82) for delivery of preterm infants in the polluted region. Data support the view that air pollution can affect the outcome of pregnancy.

Adverse pregnancy outcome in a petrochemical polluted area in Taiwan.

The petrochemical industry is the main source of industrial air pollution in Taiwan. Reported here are the results from an ongoing study of outdoor air pollution and the health of individuals living in a community in close proximity to petrochemical industrial complexes. The prevalences of term low birth weight (LBW) in the petrochemical municipality and control municipality were 3.22%, and 1.84%, respectively. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.767 (1.002-3.116) for term LBW in the petrochemical municipality. Data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy.

Calcium and magnesium in drinking water and the risk of death from breast cancer.

The relationship between mortality from breast cancer and the levels of calcium and magnesium in drinking water was examined using an ecological design. The study area consisted of 2.52 municipalities in Taiwan. Data on the levels of calcium and magnesium in drinking water were collected from the Taiwan Water Supply Corporation (TWSC). The age-standardized mortality rate (ASR) for breast cancer ( 1982-1991) was compared among municipalities with different levels of magnesium and calcium in drinking water. Weighted multivariate regression analysis was used, and after adjusting for fertility rates and urbanization, there was a significant inverse relationship between the levels of calcium and magnesium in drinking water and risk of death from breast cancer.

Chlorination of drinking water and sex ratio at birth in Taiwan.

Chlorination has been the major strategy for disinfecting drinking water in Taiwan. The objective of the present study was to determine whether the chlorination of drinking water was associated with abnormal sex ratios, an indicator of exposure to pollutants. A "chlorinating municipality" (CHM) was defined as one in which more than 90% of the municipality population was served with chlorinated water. A "nonchlorinating municipality" (NCHM) was one in which less than 5% of the municipality population was served with chlorinated water. The results of this study found no association between the use of chlorinated drinking water and abnormal sex ratios at birth in Taiwan. The imbibing of chlorinated water may not reflect contaminant exposure using sex ratio as a biomonitor.

Prevalence of shoulder and upper-limb disorders among workers in the fish-processing industry.

A cross-sectional study was conducted among fish-processing workers to evaluate the prevalence of shoulder and upper-limb discomforts and to assess the associated ergonomic risk factors. A prestructured interview, a medical check-up, and job analyses were performed to determine musculoskeletal disorders among 207 workers in eight factories. The results showed shoulder girdle pain (30.9%), epicondylitis (14.5%), and carpal tunnel syndrome (15.0%) as the three most common soft-tissue disorders. The odds ratio of shoulder girdle pain was 1.6 (95% CI 1.1-2.5) among the workers who performed tasks with repetitive movement of their upper limbs, while it was 1.8 (95% CI 1.2-2.5) for the workers who sustained forceful movement of their upper limbs during work. Women taking oral contraceptives had a 2.0 times higher odds ratio for carpal tunnel syndrome than did other women. It would appear that untrained or unskilled workers were prone to suffer from musculoskeletal disorders.

Lead poisoning caused by contaminated Cordyceps, a Chinese herbal medicine: two case reports.

Two cases of lead poisoning, caused by the Chinese herbal medicine Cordyceps, were reported to the Department of Health in a laboratory-based blood lead surveillance program. Such unusual cases of lead poisoning have not been previously reported. These two patients took Cordyceps herbal medicine for treatment of underlying diseases. Loss of appetite and anemic signs of lead poisoning were manifested in one patient with a blood lead level of 130 microg/dl, while the other patient was asymptomatic with a blood lead level of 46 microg/dl. The lead content in the Cordyceps powder was found to be as high as 20 000 ppm. After cessation of intake in the asymptomatic patient, and cessation of intake and treatment with chelating agents in the symptomatic patient, the blood lead levels returned to normal range. This report raises concerns about lead poisoning from unusual herbal medicine worldwide.

Blood lead levels in Taiwanese adults: distribution and influencing factors.

Five-thousand nine-hundred thirteen Taiwanese adults were selected by multistage sampling methods to investigate environmental lead exposure in Taiwan. The blood specimens were distributed to six laboratories for blood lead levels (BLL) measurement. The mean BLL of the 5913 Taiwanese adults was 8.28 +/- 5.39 microg/dl, with a maximum level of 57.6 microg/dl. The median was 7.0 microg/dl and 90th percentile was 15.0 microg/dl. BLLs were associated with gender, ethnic group, education level, smoking, alcohol consumption, herbal drug consumption, milk consumption, sources of drinking water, level of urbanization, and occupational lead exposure. These results showed that BLLs in Taiwanese adults were stable during the 2-year study. Most of the influencing factors were consistent with other studies, while local risk factors, such as Chinese herbal drug consumption are important ways of preventing the general population from overexposure to lead.

Acute health hazards of firefighters after fighting a department store fire.

The purpose of this study was to evaluate the health hazards of firefighters after fighting a department store fire which lasted for 40 hours. Respiratory symptoms of 168 firefighters were collected and the pulmonary functions of 149 firefighters were measured by spirometer two days after fighting the fire and compared to 32 controls. The principal symptoms manifested by firefighters were burning eyes and mucous membrane irritation. Cross-sectional study of the pulmonary functions showed that FEV1.0, FEV1.0/FVC and the flow rates (MMF, FEF25%, and FEF75%) in smoking exposed firefighters were significantly lower than those in smoking controls. However, only FEV1.0 (%) was significantly lower in nonsmoking exposed firefighters than in nonsmoking controls. Both FVC and FEV1.0 showed a declining trend with the duration of fire fighting. This study provides further evidence that firefighters are exposed to irritants during fighting a fire. Exposure to the combustion products could lead to pulmonary function defects, especially in smoking firefighters.

Assessment of interlaboratory performance on the measurement of blood lead levels in Taiwanese adults.

The purpose of this proficiency study was to assess the accuracy and consistency of blood lead level (BLLs) measurements in a study of Taiwanese adults. Three methods, including a certified blood accuracy test, an interlaboratory precision test and an intertime repeated measurement test, were applied to the six participating laboratories. Accuracy tests showed that most of the blood lead measurements were within the acceptable criteria proposed by United States Center for Disease Control and Prevention (U.S. CDC). However, an average of 11% underestimation was found at BLLs below 15 micrograms/dl. Coefficients of variation (CVs) were high in the first 3 months. After technical improvements, the CVs were reduced to acceptable limits of around 15% at low target lead values and 7% at high lead values. Interlaboratory variations of measurements in blood from ten normal healthy donors showed that the standard deviations were less than 2 micrograms/dl, which is within the acceptable criteria of +/- 4 micrograms/dl, in 8 out of 10 samples. Repeated measurements of BLLs in 54 blood samples over two months showed that most of the differences were within the acceptable range with a few exceptions. The mean BLLs measured in the baseline (pre-test) and two months later (post-test) were nearly identical. This proficiency test provides comparable and reliable results of BLL estimations in this multilaboratory study. However, the accuracy and consistency at low BLLs need to be improved.

Aircraft noise, hearing ability, and annoyance.

The relationship between aircraft noise, loss of hearing, and annoyance was explored in a study in two schools located near an international airport in Taiwan. Sixth-grade students (N = 242) were recruited from two schools and were classified into high- and low-noise-exposure groups, based on environmental noise measurements. Personal-equivalent 24-h noise exposure was measured to determine noise exposure at the individual level, and it was compared with hearing threshold level and with aircraft noise measured at the environmental level. Individual hearing threshold levels did not differ between environmental high- and low-noise-exposure groups, as evidenced by the lack of difference between the two groups for noise exposure measured at the individual level. However, the proportion of students who were annoyed by aircraft noise was higher in the environmental high-noise-exposure group, although personal 24-h noise exposure was not a factor for annoyance. The results indicated that environmental noise measurement was not an appropriate criterion for assessment of auditory damage (or noise-induced hearing loss) in Taiwan. As well, aircraft-noise exposure in Taiwan did not appear to affect the hearing threshold but nonetheless annoyed schoolchildren near the airport.

Effects of lead and noise exposures on hearing ability.

Lead and noise, via different mechanisms, may damage hearing ability, and, in some cases, cause severe and irreversible damage. To explore possible independent and synergistic effects of lead and noise on auditory function, the authors conducted a cross-sectional study in two lead-battery manufacturing factories. Lead and noise were the two most common sources of occupational exposures in the factories. Blood lead level, ambient lead concentration, noise exposure level, and hearing thresholds of 339 lead-battery workers-including clerical and managerial staffs-were measured. The authors obtained demographics and working histories via an interview-based structured questionnaire. A total of 220 lead-battery workers were exposed to high levels of lead and noise; their average blood lead concentration was 56.9 microg/dl, and their average noise exposure level was 86.0 dBALeq. Multivariate analysis, in which possible risk factors of hearing ability were considered, demonstrated a significant correlation between a high, long-term lead exposure index (defined by duration of employment and ambient lead concentration) and decreased hearing ability. In contrast, such a correlation between short-term lead exposure (defined by blood lead level) and hearing ability was not significant. Furthermore, neither noise exposure level alone nor the interaction between noise exposure level and short- or long-term lead exposure was correlated significantly with hearing ability. The present study raises an important, but typically ignored, issue: lead exposure might precipitate a more severe auditory than noise-exposure effect. The preservation of workers' hearing ability requires that preventive measures be taken against noise exposure, which is as essential as measures taken against lead exposure.

Reducing lead exposure by surveillance system: the Taiwan experience.

To evaluate the performance of a lead-surveillance program in reducing blood lead levels of workers in Taiwan, the authors conducted prospective and cross-sectional studies. A total of 6 905 workers, whose job titles indicated a direct exposure to lead in 1995, were included in this surveillance system. In this study, the authors compared the mean blood lead levels in 1994 (i.e., year of onset of surveillance) with that in 1995 in workers of major industries. Lead-exposed workers had a statistically significant decrease (i.e., average of 1.8 microg/dl) in blood lead levels during this 1-y period. The decrease was particularly obvious in individuals who worked in chemical products manufacturing, ship building/repairing, and plastic products manufacturing. The significant decreases in blood lead levels in these workers indicated that this surveillance system was effective. Surveillance, combined with control measures, might be an important means by which occupational lead exposure can be reduced.

Impaired learning and memory performance in a subclinical hypothyroidism rat model induced by hemi-thyroid electrocauterisation.

It is well known that clinical hypothyroidism (CH) can induce cognitive deficits, and the decision to start treatment for CH with thyroxine is usually straightforward. However, the relationship of cognition dysfunction with subclinical hypothyroidism (SCH) is inconsistent, and the decision concerning the need to treat SCH is controversial. In the present study, we induced a SCH rat model by hemi-thyroid electrocauterisation; then employed a serial of behavioural tests, including a beam balance, open field task and Morris water maze (MWM), to investigate the behaviour performance of SCH rats; and finally explored the protein expression of phosphorylated extracellular signal-regulated kinase (ERK)1/2 in the hippocampus by western blotting. The results demonstrated that hemi-thyroid electrocauterised rats had an elevated plasma thyrotrophin-stimulating hormone (TSH) level, with normal free thyroxine (fT4) and triiodothyronine (T3) concentrations, which defines SCH in humans. If rat SCH is diagnosed according to measurements of both plasma TSH higher than 97.5 percentile for the sham group and fT4 in the range 2.5-97.5 percentile for the sham group, the success rate of SCH modelling was 66.6%. SCH decreased exploratory behaviour but did not affect motor function in rats, showing a negative correlation of exploratory behaviour with plasma TSH concentration. Moreover, SCH rats displayed an impairment of learning and memory ability in the MWM task, with a longer escape latency in the acquisition phase and a shorter duration in the target quadrant in the test phase compared to that of sham rats. The mechanism for this might be related to the increased plasma TSH concentration, the decreased hippocampal T3 level and the enhanced expression of phosphorylated ERK1/2 in the hippocampus. The results of the present study, together with the results obtained in other studies, suggest that treatment is necessary for SCH.