Mei-Lien Chen

Differential effects of nonylphenol on testosterone secretion in rat Leydig cells

Nonylphenol (NP), a final metabolite of nonylphenol polyethoxylate, has been reported to interfere with male reproduction. However, its mechanisms are not fully understood. In the present study, we examined the effects of NP on steroidogenesis of testosterone in rat Leydig cells. The testosterone concentrations in rat plasma were examined after intravenous injection of NP (100 microg/kg) at different time intervals. In addition, rat Leydig cells were challenged with different concentrations of NP (4.25-127.5 microM) to evaluate its influences on testosterone steroidogenesis. Administration of NP showed a decrease of hCG-induced plasma testosterone. Moreover, in vitro experiments revealed that NP (127.5 microM) alone stimulated testosterone release through increase of both protein levels and activities of the StAR and P450(SCC). In contrast, NP inhibited hCG-induced testosterone release in rat Leydig cells. The inhibitory effect was also observed after incubation of the Leydig cells in the presence of different precursors. These results suggested that NP had differential effects on testosterone synthesis.

Urinary 1-hydroxypyrene concentrations in coke oven workers.

OBJECTIVES: To investigate the relation of individual occupational exposure to total particulates benzene soluble fraction (BSF) of ambient air with urinary 1-hydroxypyrene (1-OHP) concentrations among coke oven workers in Taiwan. METHODS: 80 coke oven workers and 50 referents were monitored individually for the BSF of breathing zone air over three consecutive days. Exposures were categorised as high, medium, or low among coke oven workers based on exposure situations. The high exposure group (n = 18) worked over the oven. The medium and low exposure groups (n = 41 and n = 21) worked at the side of the oven for > 4 hours and < 4 hours a day, respectively. Urine was collected before the shift on the morning of day 1 and after the shift on the afternoon of day 3 to find the change of 1-OHP concentrations across the shift. RESULTS: The median (range) changes of urinary 1-OHP concentrations across the shift for various exposure situations (microgram/g creatinine) were as follows: high 182 (7 to 3168); medium 9 (-8 to 511); low 7 (-6 to 28); and referents 0.2 (-2 to 72). This change of urinary 1-OHP was highly associated with individual occupational exposure to the BSF in air (r = 0.74 and 0.64, p < 0.001). The regression model showed significant effects of individual exposures to the BSF and alcohol consumption on urinary postshift 1-OHP after adjusting for preshift 1-OHP in the total population (n = 130). More exposure to the BSF led to higher postshift 1-OHP (p < 0.001); current drinkers of > 120 g/week had lower urinary postshift 1-OHP than never and former drinkers (p = 0.01). A 10-fold increase in the average BSF in air resulted in about a 2.5-fold increase in postshift 1-OHP among the 80 coke oven workers. CONCLUSION: Urinary 1-OHP concentrations can be used as a good biomarker to assess individual exposure to the BSF in air. Alcohol drinking may modify the toxicokinetic pathway of the BSF; the effects of alcohol should be investigated further in occupational studies.

The PM2.5 and PM10 particles in urban areas of Taiwan.

This study conducted an atmospheric aerosol sampling to measure the PM10 (particles < 10 microns in aerodynamic diameter) and PM2.5 (particles < 2.5 microns in aerodynamic diameter) mass concentrations from October 1996 to June 1997 in northern (Taipei), central (Taichung) and southern (Kaohsiung), the three largest cities of Taiwan. Seventy-eight samples were obtained to measure the mass concentrations of PM10 and PM2.5 from nine sampling sites. According to those results, the PM10 mass concentrations in Taipei, Taichung and Kaohsiung were 42.19, 60.99 and 77.10 micrograms/m3, respectively. The corresponding PM2.5 mass concentrations were 23.09, 39.97 and 48.47 micrograms/m3, respectively. The PM2.5 fraction accounted for 61-67% of the PM10 mass in central and southern Taiwan, but was lower (54-59%) in northern Taiwan. Some samples in which the PM2.5 fraction was overwhelmingly dominant could reach as high as 80-95% of the PM10 mass. In addition, the PM2.5, PM10 levels and PM2.5/PM10-2.5 (particles with aerodynamic diameters ranging from 2.5 to 10 microns) ratios in metropolitan Taiwan significantly fluctuated from site-to-site and over time. Moreover, ambient daily PM2.5 and PM10-2.5 mass concentrations did not correlate well with each other at most of the sampling sites, indicated that they originated from different kinds of sources and emitted variedly over time.

Biomonitoring of alkylphenols exposure for textile and housekeeping workers

4-Nonylphenols (NP), 4-tert-ocytylphenols (OP), and 2,4-di-tert-butylphenols (BP) are ubiquitous in daily foodstuffs. These alkylphenols are widely used in industry, and NP and OP are endocrine disruptors. This study involved biomonitoring of the alkylphenols in plasma and urine from textile and housekeeping workers. The objective was to measure the internal level of alkylphenols and clarify the occupational exposure of alkylphenols for these two working groups. Forty textile workers and 33 housekeeping workers were recruited in this study. Urine and plasma samples were enzymatic deconjugation, followed by cleanup with solid-phase extraction. After extraction, the samples were analysed with reverse-phase high-performance liquid chromatography coupled with fluorescence detection. The method was validated with the recovery and reproducibility test. The measurement results demonstrated apparent occupational exposure, since the urinary alkylphenols were significantly higher in the end-of-shift samples, 42.06 ± 46.63 ng/mL, than in the preshift samples, 23.50 ± 17.34 ng/mL, for the textile exposed workers. Meanwhile, the three kinds of alkylphenols were commonly detected in the biological samples. The plasma concentrations were higher than the urine concentrations. The average plasma concentrations of NP, OP, and BP were 53.21 ± 49.74, 16.02 ± 2.81, and 25.83 ± 7.10 ng/g for the housekeeping workers and 6.25 ± 4.83, 6.52 ± 8.67, and 6.47 ± 13.34 ng/mL in urine, respectively. The results of this study suggest that multiple exposure routes, including dietary intake, inhalation, and skin absorption, might contribute to the internal alkylphenol dose. The potential adverse effects caused by exposure of occupational workers is concerned.

The pollution characteristics of odor, volatile organochlorinated compounds and polycyclic aromatic hydrocarbons emitted from plastic waste recycling plants.

Plastic waste treatment trends toward recycling in many countries; however, the melting process in the facilities which adopt material recycling method for treating plastic waste may emit toxicants and cause sensory annoyance. The objectives of this study were to analyze the pollution characteristics of the emissions from the plastic waste recycling plants, particularly in harmful volatile organochlorinated compounds, polycyclic aromatic hydrocarbons (PAHs), odor levels and critical odorants. Ten large recycling plants were selected for analysis of odor concentration (OC), volatile organic compounds (VOCs) and PAHs inside and outside the plants using olfactometry, gas chromatography-mass spectrometry and high performance liquid chromatography-fluorescence detector, respectively. The olfactometric results showed that the melting processes used for treating polyethylene/polypropylene (PE/PP) and polyvinyl chloride (PVC) plastic waste significantly produced malodor, and the odor levels at downwind boundaries were 100-229 OC, which all exceeded Taiwans EPA standard of 50 OC. Toluene, ethylbenzene, 4-methyl-2-pentanone, methyl methacrylate and acrolein accounted for most odors compared to numerous VOCs. Sixteen organochlorinated compounds were measured in the ambient air emitted from the PVC plastic waste recycling plant and total concentrations were 245-553 microg m(-3); most were vinyl chloride, chloroform and trichloroethylene. Concentrations of PAHs inside the PE/PP plant were 8.97-252.16 ng m(-3), in which the maximum level were 20-fold higher than the levels detected from boundaries. Most of these recycling plants simply used filter to treat the melting fumes, and this could not efficiently eliminate the gaseous compounds and malodor. Improved exhaust air pollution control were strongly recommended in these industries.

Electrolyte Loss in Sweat and Iodine Deficiency in a Hot Environment

Abstract The authors studied electrolyte loss from profuse sweating in soccer-team players and evaluated the relationship between this source of iodine loss and iodine deficiency. Thirteen male soccer-team players and 100 sedentary students from the same high school were evaluated for 8 d, during which the players were training. The authors analyzed 208 sweat samples to determine losses of iodine, sodium, potassium, and calcium in sweat. Excretion of urinary electrolytes by the subjects was also measured. The mean losses of iodine, sodium, potassium, and calcium in sweat following a 1-hr game were 52 μg, 1,896 mg, 248 mg, and 20 mg, respectively; the ratios of sweat loss to urinary daily loss of the four electrolytes were 0.75, 0.2, 1.88, and 0.92, respectively. Urinary iodine was significantly (p < .02) lower than the normal level of 50 μg/gm creatinine in 38.5% of the soccer players, compared with 2% of the sedentary students. Forty-six percent of the players had Grade I goiter, compared with a mere 1 % of the sedentary students (p < .01). The results of the study suggest that loss of iodine through profuse sweating may lead to iodine deficiency, and loss of electrolytes through sweating may have a dietary significance for heat-stressed individuals or for individuals who perform heavy workloads.

Exposure assessment of PM2.5 and urinary 8-OHdG for diesel exhaust emission inspector

Animal studies have shown exposure to diesel exhaust particles (DEPs) to induce production of reactive oxygen species (ROSs) and increase levels of 8-hydroxydeoxyquanosine (8-OHdG). Controversial results have been obtained regarding the effects of workplace exposure on urinary 8-OHdG level. This study assessed concentrations of environmental PM(2.5) in DEP (DEP(2.5)), personal DEP(2.5) and urinary 8-OHdG of diesel engine exhaust emission inspector (inspector) at a diesel vehicle emission inspection station (inspection station). The analysis specifically focuses on the factors that influence inspector urinary 8-OHdG. Repeated-measures study design was used to sample for five consecutive days. A total of 25 environmental PM(2.5) measurements were analyzed at 5 different locations by using a dichotomous sampler, and a total of 55 personal PM(2.5) measurements were analyzed from inspectors by using PM(2.5) personal sampler. During the sampling period, a total of 110 pre- and post-work urine samples from inspectors, and 32 samples from the control group were collected. Following age and sex matching between the inspectors and the control group, levels of urinary 8-OHdG were analyzed. Environmental and personal concentrations of DEP(2.5) were 107.25+/-39.76 (mean+/-SD) and 155.96+/-75.70 microg/m(3), respectively. Also, the concentration of urinary 8-OHdG differed significantly between inspector and control non-smokers, averaging 14.05+/-12.71 and 6.58+/-4.39 microg/g creatinine, respectively. Additionally, urinary 8-OHdG concentrations were associated with diesel exposure after controlling for smoking and cooking at home. Compared with the control group, the inspector displayed significantly increased levels of urinary 8-OHdG. Diesel exhaust is the single pollutant involved in the exposure of DEP(2.5) at the inspection station, as confirmed by the final results.

Association between nonylphenol exposure and development of secondary sexual characteristics

Previous studies have reported that p-nonylphenol (NP) can advance the age at vaginal opening in prepubertal rats. A significant exposure levels of NP was found in Taiwanese population even from the prenatal stage. The purposes of this study are to examine the urinary NP concentration of pubertal students in Taiwan and to explore its association with the development of secondary sexual characteristics. 786 pubertal students were recruited. The NP was determined using solid-phase extraction and high-performance liquid chromatography with fluorescent detection. A self-administered questionnaire was used to collect the data on occurrence of secondary sexual characteristics in the subjects. About 30% of the urine samples were positively detected. The NP concentrations ranged from ND to 178.25 microg g(-1) cr. Fifteen percent of the Taiwanese girls between 10.5 and 10.9 years old reported having undergone menarche, which was higher than the white girls (4.6%) and the black girls (8%). There was no significant difference of urinary NP levels between groups of having and not having secondary sexual characteristics because body mass index (BMI) had significant effects on sexual development. After adjusting the effect of age and BMI, the menarcheal age remained inversely correlated with the increase of urinary NP levels. Nonylphenol exposure could disturb pubertal development and the pubertal girls seem more sensitive than pubertal boys to the exposure of endocrine disruption chemicals (EDCs). The effects of early maturation as well as the health implications need further study.

Spatial variations of airborne particles in metropolitan Taipei

During the summer and fall of 1991, total (TSP) and PM10 measurements were conducted at several sites simultaneously to evaluate the spatial variation of particle pollution in Taipei. Eighty-four samples were obtained from high-, medium- and low-polluted areas of the city. PM10 levels on roadside, sidewalk and covered walkways near a main road were 527.8 micrograms/m3, 466 micrograms/m3 and 477 micrograms/m3, respectively; the concentrations were not significantly different horizontally away from the emission sources. The PM10 concentrations on the second, seventh and 14th floors of a building were 305.31 micrograms/m3, 178.3 micrograms/m3 and 168.7 g/m3, respectively; the highest was on the second floor, but concentrations did not diminish from the seventh to the 14th floor. In addition, PM10 concentrations on the main street, side street and alley of an area were 155.3 micrograms/m3, 267.7 micrograms/m3 and 167.1 micrograms/m3, respectively; the highest concentration appeared on the side street. Furthermore, high fractions of PM10 in TSP mass were 90%, 84% and 79% for the high-, medium- and low-polluted areas. The percentages that exceed the US PM10 standard of 150 micrograms/m3 for the high- and medium-polluted areas were 100% and 71% and their exceedance was substantial. Therefore actions to mitigate the emission sources need to be fortified.

Spatiotemporal analysis of air pollution and asthma patient visits in Taipei, Taiwan

BackgroundBuffer analyses have shown that air pollution is associated with an increased incidence of asthma, but little is known about how air pollutants affect health outside a defined buffer. The aim of this study was to better understand how air pollutants affect asthma patient visits in a metropolitan area. The study used an integrated spatial and temporal approach that included the Kriging method and the Generalized Additive Model (GAM).ResultsWe analyzed daily outpatient and emergency visit data from the Taiwan Bureau of National Health Insurance and air pollution data from the Taiwan Environmental Protection Administration during 2000–2002. In general, children (aged 0–15 years) had the highest number of total asthma visits. Seasonal changes of PM10, NO2, O3 and SO2 were evident. However, SO2 showed a positive correlation with the dew point (r = 0.17, p < 0.01) and temperature (r = 0.22, p < 0.01). Among the four pollutants studied, the elevation of NO2 concentration had the highest impact on asthma outpatient visits on the day that a 10% increase of concentration caused the asthma outpatient visit rate to increase by 0.30% (95% CI: 0.16%~0.45%) in the four pollutant model. For emergency visits, the elevation of PM10 concentration, which occurred two days before the visits, had the most significant influence on this type of patient visit with an increase of 0.14% (95% CI: 0.01%~0.28%) in the four pollutants model. The impact on the emergency visit rate was non-significant two days following exposure to the other three air pollutants.ConclusionThis preliminary study demonstrates the feasibility of an integrated spatial and temporal approach to assess the impact of air pollution on asthma patient visits. The results of this study provide a better understanding of the correlation of air pollution with asthma patient visits and demonstrate that NO2 and PM10 might have a positive impact on outpatient and emergency settings respectively. Future research is required to validate robust spatiotemporal patterns and trends.