Biomedical subjects

Y L Guo

Publications and source records attributed to Y L Guo.

At least 19 recordsLinked to original sources

PubMed2005

Early diffusion weighted imaging and expression of heat shock protein 70 in newborn pigs with hypoxic ischaemic encephalopathy.

OBJECTIVE: To establish a cerebral hypoxia ischaemic model in piglets and to explore the early diffusion weighted imaging (DWI) as well as the expression of heat shock protein 70 (HSP70) with hypoxic ischaemic encephalopathy (HIE). METHODS: Twenty four 3 day old piglets were permanently ligated common carotid arteries bilaterally and ventilated with 3% oxygen for 30 minutes, and their brains were examined at three hours, six hours, and 24 hours after hypoxic ischaemia with T2 weighted images and diffusion weighted images. Apparent diffusion coefficient (ADC) values were measured and HSP70 expression was detected in the central and peripheral regions of lesions. RESULTS: Abnormal signal intensity was detected on DWI and ADC maps in three hypoxic ischaemic groups. ADC values in the central lesions rapidly decreased, whereas ADC values in the peripheral regions reduced prominently at 24 hours after hypoxic ischaemia. There were significant differences (p<0.01) between ADC values of the central regions and the peripheral regions of lesions. The number of HSP70 positive cells was low at three hours, raised at the highest peak at six hours, and then rapidly decreased. There was statistical difference between HSP70 positive cells in the central regions and those in peripheral regions (p<0.01). CONCLUSION: DWI may identify more early lesions, and improve conspicuity in the acute setting. ADC values can be used as an objective measure for hypoxic ischaemic injury. Tissue reversibility can be further reflected according to the information of ADC values and HSP70 immunohistochemical staining.

Animals↗

PubMed2005

Traffic related air pollution as a determinant of asthma among Taiwanese school children.

BACKGROUND: There is evidence that long term exposure to ambient air pollution increases the risk of childhood asthma, but the role of different sources and components needs further elaboration. To assess the effect of air pollutants on the risk of asthma among school children, a nationwide cross sectional study of 32 672 Taiwanese school children was conducted in 2001. METHODS: Routine air pollution monitoring data for sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO), and particles with an aerodynamic diameter of 10 microm or less (PM10) were used. Information on individual characteristics and indoor environments was from a parent administered questionnaire (response rate 93%). The exposure parameters were calculated using the mean of the 2000 monthly averages. The effect estimates were presented as odds ratios (ORs) per 10 ppb changes for SO2, NOx, and O3, 100 ppb changes for CO, and 10 microg/m3 changes for PM10. RESULTS: In a two stage hierarchical model adjusting for confounding, the risk of childhood asthma was positively associated with O3 (adjusted OR 1.138, 95% confidence interval (CI) 1.001 to 1.293), CO (adjusted OR 1.045, 95% CI 1.017 to 1.074), and NOx (adjusted OR 1.005, 95% CI 0.954 to 1.117). Against our prior hypothesis, the risk of childhood asthma was weakly or not related to SO2 (adjusted OR 0.874, 95% CI 0.729 to 1.054) and PM10 (adjusted OR 0.934, 95% CI 0.909 to 0.960). CONCLUSIONS: The results are consistent with the hypothesis that long term exposure to traffic related outdoor air pollutants such as NOx, CO, and O3 increases the risk of asthma in children.

Adolescent↗

PubMed2004

The pre-styloid compartment of the parapharyngeal space: a three-dimensional digitized model based on the Chinese Visible Human.

To build a digitized visible model of the parapharyngeal space of the Chinese Visible Human and to provide a sectional anatomic basis for radiological and clinical diagnosis of the parapharyngeal space, sectional anatomy data of the parapharyngeal space were selected from the Chinese Visible Human male and female to compare with MR imaging findings in the axial planes. From these data the parapharyngeal space and surrounding structures were segmented. They were then reconstructed in three dimensions on PC. In the axial planes of the sectional anatomy and MR imaging, the shape, content and relations of the parapharyngeal space were clearly displayed and the dominant plane for showing the parapharyngeal space was elicited. The three-dimensional reconstructed images displayed perfectly the anatomic relationships of the parapharyngeal space, parotid, muscles, mandible and vessels. All reconstructed structures can be displayed singly, in groups or as a whole; any diameter or angle of the reconstructed structures can be easily measured. The Chinese Visible Human male and female data set can provide complete and accurate data. The digitized model of the parapharyngeal space and its surroundings offers unique insights into the complex anatomy of the area, providing morphologic data for imaging diagnosis and surgery of the parapharyngeal space.

Anatomy, Cross-Sectional↗

PubMed2004

Glutathione S-transferase P1 gene polymorphism and air pollution as interactive risk factors for childhood asthma.

BACKGROUND: Polymorphisms at the glutathione S-transferase (GST) P1 locus were associated with asthma-related phenotypes and bronchial hyper-responsiveness. OBJECTIVE: This study investigated whether GSTP1 genotypes and outdoor air pollution were interactive risk factors on childhood asthma. METHODS: Four hundred and thirty-six subjects were recruited for oral mucosa samplings from 2853 fourth- to ninth-grade schoolchildren from three districts with different air pollution levels in southern Taiwan. PCR-based assays were performed by oral mucosa DNA to determine GSTP1 genotypes. We also conducted a nested case-control study comprising 61 asthmatic children and 95 controls confirmed by International Study of Asthma and Allergies in Childhood questionnaire results and methacholine challenge test. Multiple logistic regression was used to adjust for potential confounding factors. RESULTS: All participants were homozygous at the Ala-114 locus. Although only a marginally significant association existed between the frequency of homozygosity at the Ile-105 locus and asthma when air pollution was not considered, we found a significant gene-environmental interaction between GSTP1-105 alleles and air pollution after adjusting for confounders (P=0.035). Specifically, we found that compared with participants carrying any Val-105 allele in low air pollution, those who are Ile-105 homozygotes in high air pollution district had a significantly increased risk of asthma (adjusted odds ratio (AOR)=5.52, 95% confidence interval (CI)=1.64-21.25). Compared with participants carrying any Val-105 allele, in high air pollution district, children with Ile-105 homozygotes had a significantly increased risk of asthma (AOR=3.79, 95% CI=1.01-17.08), but those who carried two Ile-105 alleles in low or moderate air pollution districts did not show similar tendencies. The risk of asthma also revealed a clear dose-response relationship with outdoor air pollution in children with Ile-105 homozygotes. CONCLUSION: Our result suggests a gene-environmental interaction between GSTP1-105 genotypes and outdoor air pollution on childhood asthma.

Adolescent↗

PubMed2004

Are maternal psychosocial factors associated with cord immunoglobulin E in addition to family atopic history and mother immunoglobulin E?

BACKGROUND: Atopy in maternal and family histories is known to be a risk factor for elevated umbilical cord immunoglobulin E (cIgE). However, the association between cIgE and psychosocial factors remains under investigation. OBJECTIVE: To explore whether psychosocial factors in addition to atopy contribute to elevated cIgE. METHODS: Four private maternity hospitals fitting the quantile levels of SO(2) in 2000 cooperated with us by recruiting participants for this study: pairs of mothers and neonates living within 3-km catchment areas of air-monitoring stations. We used a questionnaire to collect exposure data, and the Pharmacia UniCap IgE assay test system to determine the levels of IgE in gravidas and cord blood. RESULTS: Between July 2001 and March 2003, 334 mother and neonate pairs participated in this study. The frequencies of sensitization, serum IgE (sIgE)>100 IU/mL, or cIgE> or =0.35 IU/mL were not different between the four different hospitals. By multi-variate logistic regression analysis adjusted for environmental factors, genetic factors, and psychosocial factors, the risk factors for elevated cIgE were being a male neonate (odds ratio (OR)=3.5, 95% confidence interval (CI)=[1.5, 8.5]), carpets at home (OR=3.0, 95% CI=[1.02, 8.4]), maternal allergy to dog dander (OR=9.7, 95% CI=[1.2, 98.8], maternal total serum IgE>100 IU/mL (OR=5.1, 95% CI=[2.2, 12.8]), maternal regularly/mostly/often self-reported nervousness (OR=4.0, 95% CI=[1.3, 12.8]), family income 11,574-17 361 US dollars/year (OR=3.7, 95% CI=[1.3, 11.5]), incense burning (OR=4.0, 95% CI=[1.4, 13.3]), and atopy in maternal grandparents (OR=4.8, 95% CI=[1.7, 14.0]). By principle component analysis and logistic regression, psychosocial stress (beta +/- standard error=0.26+/-0.13, P=0.04) was associated with increased cIgE. CONCLUSION: Psychosocial factors are potentially important risk factors for elevated cIgE.

Adult↗

PubMed2003

Hematological effects of Blastocystis hominis infection in male foreign workers in Taiwan.

Blastocystis hominis found in stool specimens has been the most frequently identified parasite among foreign workers from Southeast Asia in Taiwan since 1992. The prevalence of B. hominis was 14.1% in this study. In their quarantine physical examinations, 121 male Thai workers were examined hematologically and screened for stool parasites using the merthiolate-iodine-formaldehyde concentration method. Hematological values were compared in workers with and without a B. hominis infection. Multiple regressions were used to adjust for age. Those infected with any parasite other than B. hominis were excluded from further analysis. The workers infected with B. hominis had a lower leukocyte count (6.5+/-0.4 X 10(3)/microl) than those who were not (7.4+/-0.2 X 10(3)/microl). This was mainly caused by a reduced neutrophil count (3.2+/-0.4 vs 4.2+/-0.2 X 10(3)/microl). Hemoglobin (13.9+/-0.3 vs 14.5+/-0.1 g/dl) and hematocrit (41.4+/-0.6 vs 42.9+/-0.2%) were also reduced in B. hominis-positive workers.

Adult↗

PubMed2003

Central neurological abnormalities and multiple chemical sensitivity caused by chronic toluene exposure.

Multiple chemical sensitivity (MCS) is a syndrome in which multiple symptoms occur with low-level chemical exposure; whether it is an organic disease initiated by environmental exposure or a psychological disorder is still controversial. We report a 38-year-old male worker with chronic toluene exposure who developed symptoms such as palpitation, insomnia, dizziness with headache, memory impairment, euphoria while working, and depression during the weekend. Upon cessation of exposure, follow-up neurobehavioural tests, including the cognitive ability screening instrument and the mini-mental state examination, gradually improved and eventually became normal. Although no further toluene exposure was noted, non-specific symptoms reappeared whenever the subject smelled automotive exhaust fumes or paint, or visited a petrol station, followed by anxiety with sleep disturbance. During hospitalization for a toluene provocation test, there was no difference between pre-challenge and post-challenge PaCO(2), PaO(2), SaO(2) or pulmonary function tests, except some elevation of pulse rate. The clinical manifestations suggested that MCS was more relevant to psychophysiological than pathophysiological factors.

Adult↗

PubMed2003

Climate, traffic-related air pollutants and allergic rhinitis prevalence in middle-school children in Taiwan.

The prevalence of allergic rhinitis, a common respiratory disorder, may be rapidly increasing. Epidemiological studies, however, indicate little about its association with climatic factors and air pollution. The relationship between traffic-related air pollutants and allergic rhinitis in middle-school students was therefore investigated. In a nationwide survey of middle-school students in Taiwan conducted in 1995/1996, the lifetime prevalence of physician-diagnosed allergic rhinitis and typical symptoms of allergic rhinitis were compared with air-monitoring station data on temperature, relative humidity, sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO) and particulate matter with a 50% cut-off aerodynamic diameter of 10 microm (PM10). A total of 331,686 nonsmoking children attended schools located within 2 km of 55 stations. Mean (range) annual exposures were: CO 853 (381-1,610) parts per billion (ppb), NOx 35.1 (10.2-72.4) ppb, SO2 7.57 (0.88-21.2) ppb, PM10 69.2 (40.1-116.2) microg x m(-3), O3 21.3 (12.4-34.1) ppb, temperature 22.9 (19.6-25.1) degrees C, and relative humidity 76.2 (64.8-86.2)%. The prevalence of physician-diagnosed allergic rhinitis was 28.6 and 19.5% in males and females, respectively, with prevalence of questionnaire-determined allergic rhinitis 42.4 and 34.0%. After adjustment for age, parental education and history of atopic eczema, physician-diagnosed allergic rhinitis was found to be associated with higher nonsummer (September-May) warmth and traffic-related air pollutants, including CO, NOx and O3. Questionnaire-determined allergic rhinitis correlated only with traffic-related air pollutants. Nonsummer warmth and traffic-related air pollution, probably mediated through exposure to common allergens such as dust mites, are possible risk factors for allergic rhinitis in middle-school-aged children.

Adolescent↗

PubMed2001

Adenylyl cyclase Rv1625c of Mycobacterium tuberculosis: a progenitor of mammalian adenylyl cyclases.

The gene Rv1625c from Mycobacterium tuberculosis encodes a membrane-anchored adenylyl cyclase corresponding to exactly one-half of a mammalian adenylyl cyclase. An engineered, soluble form of Rv1625c was expressed in Escherichia coli. It formed a homodimeric cyclase with two catalytic centers. Amino acid mutations predicted to affect catalysis resulted in inactive monomers. A single catalytic center with wild-type activity could be reconstituted from mutated monomers in stringent analogy to the mammalian heterodimeric cyclase structure. The proposed existence of supramolecular adenylyl cyclase complexes was established by reconstitution from peptide-linked, mutation-inactivated homodimers resulting in pseudo-trimeric and -tetrameric complexes. The mycobacterial holoenzyme was expressed successfully in E.coli and mammalian HEK293 cells, i.e. its membrane targeting sequence was compatible with the bacterial and eukaryotic machinery for processing and membrane insertion. The membrane-anchored mycobacterial cyclase expressed in E.coli was purified to homogeneity as a first step toward the complete structural elucidation of this important protein. As the closest progenitor of the mammalian adenylyl cyclase family to date, the mycobacterial cyclase probably was spread by horizontal gene transfer.

Adenylyl Cyclases↗

PubMed2001

p38beta MAP kinase protects rat mesangial cells from TNF-alpha-induced apoptosis.

p38 MAP kinases (p38) and c-Jun N-terminal protein kinases (JNK) have been associated with TNF-alpha-induced apoptosis. However, recent studies indicate that an early but brief activation of JNK and/or p38 may actually protect some cells from TNF-alpha-induced apoptosis. Whether the activation of JNK and p38 provides a pro- or anti-apoptotic signal for TNF-alpha has been controversial. In this study, we investigated the role of p38 in the regulation of TNF-alpha cytotoxicity in rat mesangial cells. Treatment of the cells with TNF-alpha alone had little effect on their viability, but they became very sensitive to apoptosis when treated with TNF-alpha in the presence of the p38 inhibitor SB 203580. These results suggested that the p38 pathway is critical for mesangial cells to survive the toxic effect of TNF-alpha. Using adenovirus-mediated gene transfer technique, we further demonstrated that p38beta, but not p38alpha, is essential to protect the cells from TNF-alpha toxicity. It has been speculated that there is a synergetic interaction between the p38 and the nuclear factor-kappaB (NF-kappaB) pathways in protecting certain cells from apoptosis. However, expression of neither p38beta nor its dominant negative mutant in mesangial cells interfered with TNF-alpha-induced translocation of NF-kappaB, the initial step of NF-kappaB activation. While it is unclear whether p38beta regulates NF-kappaB transcription activity at other steps, it is apparent that p38beta does not affect TNF-alpha-induced NF-kappaB activation at the stage of nuclear translocation.

Adenoviridae↗

PubMed2001

Hepatic enzyme induction and acute endocrine effects of 2,2',3,3',4,6'-hexachlorobiphenyl and 2,2',3,4',5',6-hexachlorobiphenyl in prepubertal female rats.

Polychlorinated biphenyls (PCBs) with the liable 2,3,6-substitution are important components of certain commercial mixtures and frequently detected in biota, but little is known about their enzyme induction abilities and possible endocrine-disrupting effects. CB 132 (2,2',3,3',4,6'-hexachlorophenyl) and CB 149 (2,2'3,4',5',6-hexachlorophenyl) were investigated in weanling female rats dosed intraperitoneally on days 21 and 22 and killed on day 24 of age. Uterotropic response, serum thyroid hormone, and hepatic enzyme induction were examined in prepubertal female rats treated with these two environmentally relevant 2,3,6-substituted chlorobiphenyl (CB) congeners from 8 mg/kg to 96 mg/kg. The readily metabolized CB 132 did not cause any significant increase in all endpoints measured in the present study. On the other hand, CB 149 was a weak PROD and BROD inducer and a modest depleter of serum thyroxine in prepubertal female rats. The finding of thyroid hormone disruption by CB 149 may lead to biologically significant neurobehavioral and neurochemical changes in developing animals via milk lactation.

Animals↗

PubMed2001

A national survey of psychosocial job stressors and their implications for health among working people in Taiwan.

OBJECTIVES: The prevalence of job stress, distributions of major job stressors, and the associations of job stress with multiple self-reported health complaints were examined in a national survey conducted in 1994 in Taiwan. METHODS: A total of 9,746 men and 5,599 women who were employed at the time of the survey and aged between 25 and 65-years were studied. Information on employment status, perceived level of job stress, major job stressors, and health complaints were obtained by a self-administered questionnaire. RESULTS: Overall, 7.6% of men and 6.5% of women reported often or always feeling very stressed at work. Higher levels of perceived job stress were found among subjects who were younger, with higher education level, working in a larger firm, working for longer hours per week, and who were administrators or managers. Problems with individual job content were ranked as the most important job stressor in men across all employment categories and in most women. Other major job stressors included problems with monetary rewards and lack of career prospects. The patterns of major job stressors appear to vary by employment grade and by gender. After adjustment for age and education, employees who perceived higher levels of job stress had significantly increased risks of multiple health problems, including strained eyes, ringing ears, chronic cough with phlegm, chest tightness. stomach problems, headache, and musculoskeletal discomfort. CONCLUSIONS: These results suggest that psychosocial stress in the workplace has profound impacts on health. This study identified high-risk groups and major types of job stressors for further investigation.

Adult↗

PubMed2001

Morphology of glass fibers in electronics workers with fiberglass dermatitis--a scanning electron microscopy study.

BACKGROUND: Fiberglass is used as a reinforcement filler material in printed circuit boards (PCBs) which are widely used in the electronics industry. In a recent survey, we demonstrated that fiberglass dermatitis is the most common occupational dermatosis among electronics industry workers in Taiwan. Little is known, however, about the morphologic structures of the glass fibers which induce dermatitis. The purpose of this study was to assess the morphology of fiber spicules and to determine the relationship of this structure to fiberglass dermatitis. METHODS: Fourteen female patients with a diagnosis of fiberglass dermatitis were selected for study. The diagnosis was confirmed in all patients by positive skin stripping for glass fibers and matching with glass fibers from dust collected in work areas and from samples collected by scraping the edge of PCBs. Samples of collected glass fibers were analyzed by scanning electron microscopy (SEM). RESULTS: SEM of the fiberglass samples revealed that fibers were approximately 10 microm in diameter. In samples from both the edge of PCBs and from dust collected in work areas, SEM revealed that most of the fibers were in bundles of various sizes and lengths. All fibers collected from patients' skin by tape stripping showed a singular spicule, most had a sharp free end, and the lengths were in the range 50-150 microm . CONCLUSIONS: Singular glass fibers with a sharp free end and a length of 50-150 microm are most likely to induce fiberglass dermatitis.

Adult↗

PubMed2001

Sharps injuries among hospital support personnel.

Sharps injuries (SIs) among support personnel in hospitals have received little attention in the scientific literature. A cross-sectional study was undertaken to measure the incidence of SIs in Taiwanese support personnel. All support personnel, including laundry workers, cleaners, porters and central supply workers, from 16 hospitals were surveyed for SIs, sustained between June 1996 and July 1997. Either a questionnaire or face-to-face interviews, for those staff with a literacy problem, were used. Of the 862 persons eligible for study, 79.4% (684) were evaluable. Few staff (30.4%) had attended a prevention programme and 61% had suffered an SI in the past year. Few (25.4%) reported their injury. Hollow-bore needles, of which 72.2% had been used, were associated with 42.2% of injuries. Cleaners sustained the majority (65.7%) of injuries, and inappropriate disposal was associated with 54.7% of all injuries. For those staff employed for more than four years, the risk of sustaining an injury increased significantly with length of employment (P<0.001). Most of the injuries were sustained by cleaners handling sharps inappropriately disposed of by clinical staff. A safer environment for support staff could be achieved with the co-operation of clinical staff to correctly dispose of sharps to ensure single handling of sharps. A formal orientation of support staff in the reporting of SIs would enable clinical assessment and management of injuries, as well as an evaluation of needle and sharps safety in the healthcare setting.

Accidents, Occupational↗

PubMed2001

Environmental and occupational skin diseases in Taiwan.

This presentation focuses on the four most important skin diseases in Taiwan thought to be of environmental and/or occupational origin. The majority of work-related dermatoses are contact dermatitis patients. Among occupational contact dermatitis patients, 58.5% involved irritant and 41.5%, allergic dermatitis. Electronics, hairdressing, medical practice, and construction were the most important occupations causing contact dermatitis. An endemic occurrence of chronic arsenism causing hyperpigmentation, keratosis, and cancer has been reported in Taiwan. Arsenical skin cancers present as multiple lesions at different disease stages. The skin cancers are usually found in non-sun-exposed areas. UVB exerts an inhibitory effect on the proliferation of arsenical cancers; this may explain its non-sun-exposed nature. An outbreak of premalignant and malignant skin lesions was reported among paraquat manufacturers in 1985. The skin lesions were mainly distributed over the sun-exposed areas. Photodamage and photocarcinogenesis revealed a strong association with exposure to bipyridines among paraquat manufacturers. In 1979, a mass poisoning occurred in Taiwan from cooking oil contaminated by polychlorinated biphenyls (PCBs). Over 60% of patients were in grades O-II by the Japanese classification. The blood PCB levels of the Taiwanese patients were found to be higher than those of the Yusho subjects.

Arsenic↗

PubMed2001

Kininostatin, an angiogenic inhibitor, inhibits proliferation and induces apoptosis of human endothelial cells.

We recently reported that domain 5 (D5) of high-molecular-weight kininogen inhibited critical steps required for angiogenesis. Thus, it was named kininostatin. To understand its mechanism of action, we further investigated the effects of D5 on basic fibroblast growth factor (bFGF)-induced endothelial cell proliferation and cell viability. We report here that D5-inhibited cell proliferation of human endothelial cells stimulated by bFGF was associated with a significant reduction of cyclin D1 expression, which is a critical component required for the transition from G(1) to S phase of the cell cycle. However, inhibition of cell proliferation by D5 was not due to an inhibition of extracellular signal-regulated protein kinase activity. Endothelial cells underwent apoptosis when cultured in a serum-free medium, which was prevented by bFGF. D5 reversed the protective effect of bFGF by 80%. Cells treated with D5 in the presence of bFGF showed typical morphological features of apoptosis, which was further confirmed by 2 additional assays: Hoechst 33258 cell staining and DNA fragmentation analysis. We conclude that the inhibition of endothelial cell proliferation and induction of apoptosis together represent a major contribution to the antiangiogenic activity of D5.

Angiogenesis Inhibitors↗

PubMed2001

Effect of prenatal exposure to polychlorinated biphenyls on cognitive development in children: a longitudinal study in Taiwan.

BACKGROUND: From 1978 to 1979, a group of people in Taiwan were exposed to high levels of heat-degraded polychlorinated biphenyls (PCBs) owing to accidental ingestion of contaminated rice oil. Children born to mothers following the exposure ('Yucheng' children) were known to have hyperpigmented skin and other dysmorphology after birth. AIMS: To determine the effect of prenatal exposure to PCBs on cognitive development in Yucheng children. METHOD: One hundred and eighteen Yucheng children prenatally exposed to PCBs and degradation products, and community-matched control children who were exposed to background levels only, were followed from 1985 to 1998. The Bayley Scale for Infant Development, Chinese version of the Stanford-Binet IQ Test, Raven's Coloured Progressive Matrices and Raven's Standardised Progressive Matrices were used to assess the cognitive development of these children. RESULTS: The Yucheng children scored lower than control children on each of these methods of measurement between the ages of 2 and 12 years. CONCLUSIONS: Prenatal exposure to PCBs and their derivatives has long-term adverse effects on cognitive development in humans.

Child↗

PubMed2001

Reduction of sperm motility in a male laboratory worker exposed to solvents: a case study.

A 34-year-old male laboratory worker suffered from asthenospermia and fertility problems. He was suspected of having been exposed to solvents used at work due to a malfunction of the ventilation system in his laboratory from August 1996 to April 1997. A laboratory walk-through and air and bulk sample collection were performed to determine the possible exposure levels of chemical hazards in his job. The scenario was reconstructed to simulate the worker's previous exposure during the ventilation shutdown period. It was found that the worker was possibly exposed to chloroform at levels of 10 or 50 times higher than the permissible exposure limit or the threshold limit value of 2 hr/day, 5.5 days/week, and 4.25 weeks/month for 8 months. Because chloroform is known to be spermatotoxic, the possibility of chloroform causing the worker's asthenospermia cannot be ruled out. Further study on spermatotoxicity of chloroform is warranted.

Adult↗