Cellular mechanisms underlying extraordinary sulfide tolerance in a crustacean holobiont from hydrothermal vents.

The shallow-water hydrothermal vent system of Kueishan Island has been described as one of the world's most acidic and sulfide-rich marine habitats. The only recorded metazoan species living in the direct vicinity of the vents is Xenograpsus testudinatus, a brachyuran crab endemic to marine sulfide-rich vent systems. Despite the toxicity of hydrogen sulfide, X. testudinatus occupies an ecological niche in a sulfide-rich habitat, with the underlying detoxification mechanism remaining unknown. Using laboratory and field-based experiments, we characterized the gills of X. testudinatus that are the major site of sulfide detoxification. Here sulfide is oxidized to thiosulfate or bound to hypotaurine to generate the less toxic thiotaurine. Biochemical and molecular analyses demonstrated that the accumulation of thiosulfate and hypotaurine is mediated by the sodium-independent sulfate anion transporter (SLC26A11) and taurine transporter (Taut), which are expressed in gill epithelia. Histological and metagenomic analyses of gill tissues demonstrated a distinct bacterial signature dominated by Epsilonproteobacteria. Our results suggest that thiotaurine synthesized in gills is used by sulfide-oxidizing endo-symbiotic bacteria, creating an effective sulfide-buffering system. This work identified physiological mechanisms involving host-microbe interactions that support life of a metazoan in one of the most extreme environments on our planet.

Decline in semen quality in men in northern Taiwan between 2001 and 2010.

Semen quality is a key indicator of the male reproductive ability. The decline in semen quality has been debated for several decades. However, data on decline in semen quality might be inconsistent given factors such as geographical area, ethnicity, environmental exposure and lifestyle changes. This study aimed to provide information on the semen quality of men in Northern Taiwanese. We recruited 7,187 male participants between 2001 and 2010 from a reproductive medical center. The age of the participants ranged from 26 to 57 years, with a mean age of 36.9 ± 4.77 years. Semen analysis was performed through standardized methods outlined in the World Health Organization laboratory manual. Increasing age (per year) was significantly and negatively associated with semen volume (1.006 ml), progressive sperm motility, rapid progressive sperm motility and sperm with normal morphology (reduction by 1.010%, 1.013% and 1.002% per year, respectively). In addition, sperm concentration, semen volume, number of sperms, progressive sperm motility, rapid progressive sperm motility, and sperm with normal morphology were significantly reduced annually by 1.013 × 106/ml, 1.015 ml, 1.028 × 106, 1.021 %, 1.017% and 1.016%, respectively). Age-period-cohort (APC) analyses revealed that age and cohort had effects on reduction of the progressive and rapid progressive sperm motility. Moreover, all the sperm parameter values were significantly reduced annually. Our findings provide useful information for clinical practice and public health investigations of male reproductive health.

Renin-angiotensin-aldosterone system related gene polymorphisms and urinary total arsenic is related to chronic kidney disease.

A recent study demonstrated that an increased risk of chronic kidney disease (CKD) was associated with high urinary total arsenic levels. However, whether genomic instability is related to CKD remains unclear. An association between CKD and genetic polymorphisms of regulation enzymes of the renin-angiotensin-aldosterone system (RAAS), such as angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II type I receptor (AT1R), and aldosterone synthase (CYP11B2) has not been shown. The aim of the present study was to investigate the relationship between arsenic, genetic polymorphisms of RAAS enzymes and CKD. A total of 233 patients and 449 age- and gender-matched controls were recruited from the Taipei Medical University Hospital, Taipei Municipal Wan Fang Hospital and the Shin Kong Wu Ho-Su Memorial Hospital. Concentrations of urinary arsenic were determined by a high-performance liquid chromatography-linked hydride generator, and atomic absorption spectrometry. Polymorphisms of ACE(I/D), AGT(A[-20]C), (T174M), (M235T), AT1R(A1166C) and CYP11B2(C[-344]T) were examined by polymerase chain reaction and restriction fragment length polymorphism. Subjects carrying the CYP11B2 TT genotype had a higher odds ratio (OR), 1.39 (0.96-2.01), of CKD; while those with the AGT(A[-20]C) CC genotype had an inverse OR of CKD (0.20 (0.05-0.81)), and a high-risk genotype was defined as A/A+A/C for AGT(A[-20C]) and T/T for CYP11B2(C[-344]T). The trend test showed a higher OR for CKD in patients who had either high urinary total arsenic levels or carried the high-risk genotype, or both, compared to patients with low urinary total arsenic levels, who carried the low-risk genotype, and could also be affected by the hypertension or diabetes status.

Efficacy of antimicrobial peptide P113 oral health care products on the reduction of oral bacteria number and dental plaque formation in a randomized clinical assessment.

Background/purpose: Dental plaque is the main cause leading to the dental caries and periodontal diseases. The main purpose of this study was to test the efficacy of oral spray containing the antimicrobial peptide P-113 on the reduction of oral bacteria number and dental plaque formation in a randomized clinical assessment. Materials and methods: This study was divided into two parts. In Part A, we investigated the user experiences with the P-113 containing oral spray. In part B, 14 subjects in the experimental group used the P-113-containing oral spray, while 14 subjects in the control group used a placebo without the P-113 in a 4-week clinical trial. Participants were asked to use the P-113-containing oral spray or placebo 3 times per day and 5 times per use. Moreover, 3 check-ups and 2 washouts were carried out to evaluate the DMFT score, dental plaque weight, dental plaque index, and gingival index. Results: In part A, up to 91.8% of the subjects in the experimental group were satisfied with the use of the P-113-containing oral spray. In part B, based on our PacBio SMRT sequencing platform and DADA2 analysis, the numbers of Streptococcus and Porphyromonas in the experimental group were lower than those in the control group. In addition, decreased dental plaque weight, dental plaque index, and gingival index were all observed in the experimental group. Conclusion: The P-113-containing oral spray has the potential to reduce the dental caries and periodontal disease-related bacteria and to control the dental plaque formation.

Environmental tobacco smoke and arsenic methylation capacity are associated with urothelial carcinoma.

BACKGROUND/PURPOSE: Cigarette smoking, exposure to secondhand smoke, and arsenic exposure are well known risk factors for developing urothelial carcinoma (UC). We investigated the combined effects of cigarette smoking, exposure to secondhand smoke, and the presence of urinary total arsenic on the risk of developing UC. METHODS: We conducted a hospital-based, case-control study involving 261 UC patients and 672 cancer-free control individuals between September 2002 and May 2009. RESULTS: Individuals who had smoked <100 cigarettes in their lifetime (never smokers) and had a high urinary total arsenic level (≥15.40 µg/g creatinine), and those who had smoked >100 cigarettes in their lifetime (ever smokers) and had a high urinary total arsenic level, had increased risks of developing UC (3.20-fold and 6.45-fold greater), respectively, compared to individuals who were never smokers and had a low urinary total arsenic level. Individuals who had high urinary total arsenic levels and had been exposed to secondhand smoke, and individuals with high urinary arsenic levels who had not been exposed to secondhand smoke, had increased chances (2.71-fold and 5.00-fold greater, respectively) of developing UC, compared to individuals who were not exposed to secondhand smoke and had low urinary total arsenic levels. Ever smokers who had been exposed to secondhand smoke and had a high urinary total arsenic level had the greatest increased risk for developing UC (10.82-fold greater). CONCLUSION: Individuals in a Taiwanese population who smoked cigarettes, were exposed to secondhand smoke, and a high urinary total arsenic level, had a significant risk for developing UC.

Moving toward people's needs for smoke-free restaurants: before and after a national promotion program in Taiwan, 2003-2005.

INTRODUCTION: In Taiwan, the Smoke-Free Restaurant Program (SFRP) was implemented from 2003 to 2005 as an initial phase before the introduction of restrictive legislation promoting smoke-free restaurants (SFRs). No studies have evaluated trends in public opinion before and after a national health promotion campaign for the introduction of SFRs on a voluntary basis. The present study investigated whether public opinion with respect to eliminating environmental tobacco smoke (ETS) in restaurants changed after implementation of the SFRP. METHODS: Data were obtained from four large-scale, nationally representative surveys conducted in 2003-2005 before and after implementation of the SFRP. Weighted analyses were performed to obtain nationally representative results. RESULTS: After a series of SFRP campaigns, reported exposure to ETS in restaurants by survey participants decreased by approximately 14%. Approximately 20% more people had heard of SFRs, and approximately 25% more had chosen to dine in a smoke-free restaurant. We found consistently high community support for SFRs (ca. 95%), and approximately 80% supported smoke-free restaurant legislation, although both rates dropped slightly in 2005. People aged 60 years or more, nonsmokers, and those who had greater knowledge of ETS hazards were more likely to support smoke-free restaurant legislation. DISCUSSION: The SFRP was effective at promoting SFRs on a voluntary basis. Strong community endorsement has major implications for legislators who are considering the nature and extent of further smoke-free restaurant legislation in Taiwan and other countries.

Author Correction: The Methylation Capacity of Arsenic and Insulin Resistance are Associated with Psychological Characteristics in Children and Adolescents.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Estimation of acceptable mercury intake from fish in Taiwan.

The US Food and Drug Administration (USFDA) and Environmental Protection Agency (USEPA) are advising women and young children to avoid eating fish that contain high levels of mercury (Hg). However in Taiwan, the annual Black Fin Tuna Festival encourages the public to consume fish. The aim of this study was to assess fish intake in relation to the health risks of mercury exposure and calculate the acceptable and safe intake of fish in children and women of childbearing age. From the Monte Carlo simulation, based on USEPA's reference dose (0.1 microgkg(-1)d(-1)), we found that 21.6%-24.3% and 45.6%-57.4% of the daily mercury dose estimates exceeded the reference dose for typical and high-seafood consumers. The acceptable ingestion rates are <50 g d(-1) (children) and 90.8 +/- 15.7 g d(-1) (women of childbearing). Sensitivity analysis suggests that Hg concentration in fish may be a key parameter to aid governments as they offer guidance for risk management.

The Methylation Capacity of Arsenic and Insulin Resistance are Associated with Psychological Characteristics in Children and Adolescents.

The goal of the present study was to compare the influence of the methylation capacity of arsenic, as well as insulin resistance on psychological characteristics of school students from elementary and junior high school. 296 elementary and 318 junior high school students participated in health examinations, completed questionnaires and determined their concentrations of urinary arsenic species and psychological characteristics. Insulin resistance was determined by means of the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). We found that HOMA-IR values were significantly related to increased score of the depression and anger after adjusted for age, gender, schools, father's educational levels, mother's educational levels, BMI, body fat, and urinary creatinine in all students. Anxiety scores and depression scores of junior high school children were significantly higher compared to elementary school children, but lower in disruptive behavior scores. HOMA-IR levels were significantly inversely related to self-concept scores in junior high school students. A greater urinary inorganic arsenic percentage (iAs%) was marginally significantly related to a higher depression score in junior high school students. This is the first study to show a relationship between HOMA-IR levels or urinary arsenic profiles and psychological distress in school students from elementary and junior high school.

Effect of the mother's consumption of traditional Chinese herbs on estimated infant daily intake of lead from breast milk.

Infant exposure to lead through breast milk is of special concern because breast milk is considered the best food source for infants under 6 months. In this study, a total of the mothers provided colostrum samples once in the early postpartum period, but only 16 of them provided breast milk weekly at 1-60 days postpartum. The geometric mean of lead concentrations in all colostrum samples (n=72) was 7.68+/-8.24 microg/L. The concentration of lead in the breast milk of the consumption group (the mothers who consumed traditional Chinese herbs) was 8.59+/-10.95 microg/L, a level significantly higher than the level of 6.84+/-2.68 microg/L found in the control group (mothers who did not consume traditional Chinese herbs). In the consumption group (n=9), the mean concentration of lead in the breast milk decreased with days postpartum, from 9.94 microg/L in colostrum to 2.34 microg/L in mature milk. We found the highest daily lead intake in infants at birth, and the level gradually decreased after the first month. We used an estimation of the hazard index (HI) to analyze the health risk of infants. In total, 5.7% (2 out of 35) of the HI estimates exceed 1.0 for the consumption group. In conclusion, the consumptions of traditional Chinese herbs by the mothers in this study significantly affected the body burden of lead in their infants.

Analysis of the health risk of exposure to breast milk mercury in infants in Taiwan.

The aim of this study was to assess the total concentration and health risk to infants of breast milk mercury in urban mothers and mothers married to fishermen in relation to fish intake in Taiwan. A total of sixty-eight healthy mothers were recruited for the study. The breast milk mercury geometric mean concentration was 2.02 microgl(-1) (n=56, range: 0.24-9.45 microgl(-1)) for the city group and 2.04 microgl(-1) (n=12, range: 0.26-8.62 microgl(-1)) for the fishermen's group. Of the three sources of mercury exposure (i.e., ingestion (breast milk), inhalation (ambient air), and dermal exposure (shower)), breast-feeding was found to be the largest (96.3-99.6% of the total). From a Monte Carlo simulation, in which methyl mercury accounted for about 50% of total mercury, the hazard quotient (exposure estimate/oral minimal risk level or target organ toxicity dose) exceeded 1.0 for 12.9% of urban babies and 18.8% of fishermen's babies (chronic oral minimal risk level and target organ toxicity dose: 3 x 10(-4)mgkg(-1)d(-1)). The calculated mercury exposure was 3.02 x 10(-1) microgkg(-1)d(-1) for a 3.49 kg urban baby boy and 3.06 x 10(-1) microgkg(-1)d(-1) for a 3.44 kg urban baby girl. These results suggest the life style of mothers (eating raw fish and shellfish such as used in "Sashimi" and "Sushi," and vitamin supplementation) may influence the mercury concentration in breast milk.

Effect of welding fume on heart rate variability among workers with respirators in a shipyard.

Welding fume exposure is associated with heart rate variability (HRV) reduction. It is still unknown whether respirator can reduce effect of welding fume on HRV among welding workers in a shipyard. We recruited 68 welding workers with respirator and 52 welding workers without respirator to measure HRV indices, including standard deviation of normal-to-normal intervals (SDNN) and square root of the mean squared differences of successive intervals (r-MSSD) by ambulatory electrocardiographic (ECG). Personal exposure to particulate matter less than or equal to 2.5 µm in diameter (PM2.5) was measured by a dust monitor. The association between 5-minute mean PM2.5 and log10-transformed HRV indices was analyzed by mixed-effects models. We found 5-minute mean PM2.5 was associated with 8.9% and 10.3% decreases in SDNN and r-MSSD. Effect of PM2.5 on HRV indices was greatest among workers without respirator {SDNN: 12.4% (95% confidence interval = -18.8--6.9); r-MSSD: 14.7% (95% confidence interval = -20.8--8.6)}. Workers with respirator showed slight decreases in HRV indices {SDNN: 2.2% (95% confidence interval = -6.3--1.9); r-MSSD: 4.0% (95% confidence interval = -6.4--1.6)}. We conclude that respirator use reduces the effect of PM2.5 exposure on HRV among workers performing welding in a shipyard.

Exposure to ambient bioaerosols is associated with allergic skin diseases in Greater Taipei residents.

Allergic skin diseases may result from various types of chemical and biological allergens. This study investigated the association between ambient bioaerosol exposure and allergic skin diseases by using the exposure data obtained from land use regression models and interpolated data. Data on daily average outpatient visits for atopic dermatitis (ICD-9-CM 691.8) and contact dermatitis and other eczema (ICD-9-CM 692.9) between November 2011 and August 2012 were obtained from the National Health Insurance Research Database. A generalized estimating equation was used to analyze the associations between the skin diseases and ambient bioaerosol levels. The results indicated that during the study period, contact dermatitis and other eczema were more prevalent than atopic dermatitis in the study area. Most cases were observed in districts of Taipei City and 3 major districts of New Taipei City, namely Xinzhuang, Banqiao, and Xindian. In univariate analysis, most bioaerosols were positively associated with both skin diseases. After adjustment for air pollution and sociodemographic factors, exposure to total fungal spores was significantly associated with atopic dermatitis in males (relative risk [RR] = 1.12; 95% confidence interval [CI] = 1.05-1.19). Contact dermatitis and other eczema had significant relationships with Cladosporium in males (RR = 1.07; 95% CI = 1.02-1.14) and with Aspergillus/Penicillium in females (RR = 1.04; 95% CI = 1.02-1.07). Meteorological parameters, namely wind speed, temperature, and rainfall, were also significantly associated with skin diseases. Our findings reveal that exposure to ambient bioaerosols is a significant and independent risk factor for allergic skin diseases.

Effects of acupuncture on menopause-related symptoms and quality of life in women in natural menopause: a meta-analysis of randomized controlled trials.

OBJECTIVE: This meta-analysis aims to evaluate the effects of acupuncture on hot flash frequency and severity, menopause-related symptoms, and quality of life in women in natural menopause. METHODS: We systematically searched PubMed/Medline, PsychINFO, Web of Science, Cochrane Central Register of Controlled Trials, and CINAHL using keywords such as acupuncture, hot flash, menopause-related symptoms, and quality of life. Heterogeneity, moderator analysis, publication bias, and risk of bias associated with the included studies were examined. RESULTS: Of 104 relevant studies, 12 studies with 869 participants met the inclusion criteria and were included in this study. We found that acupuncture significantly reduced the frequency (g = -0.35; 95% CI, -0.5 to -0.21) and severity (g = -0.44; 95% CI, -0.65 to -0.23) of hot flashes. Acupuncture significantly decreased the psychological, somatic, and urogenital subscale scores on the Menopause Rating Scale (g = -1.56, g = -1.39, and g = -0.82, respectively; P < 0.05). Acupuncture improved the vasomotor subscale score on the Menopause-Specific Quality of Life questionnaire (g= -0.46; 95% CI, -0.9 to -0.02). Long-term effects (up to 3 mo) on hot flash frequency and severity (g = -0.53 and g = -0.55, respectively) were found. CONCLUSIONS: This meta-analysis confirms that acupuncture improves hot flash frequency and severity, menopause-related symptoms, and quality of life (in the vasomotor domain) in women experiencing natural menopause.

Effects of commuting mode on air pollution exposure and cardiovascular health among young adults in Taipei, Taiwan.

The association between traffic-related air pollution and adverse cardiovascular effects has been well documented; however, little is known about whether different commuting modes can modify the effects of air pollution on the cardiovascular system in human subjects in urban areas with heavy traffic. We recruited 120 young, healthy subjects in Taipei, Taiwan. Each participant was classified with different commuting modes according to his/her own commuting style. Three repeated measurements of heart rate variability (HRV) indices {standard deviation of NN intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD)}, particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5), temperature, humidity and noise level were conducted for each subject during 1-h morning commutes (0900-1000 h) in four different commuting modes, including an electrically powered subway, a gas-powered bus, a gasoline-powered car, and walking. Linear mixed-effects models were used to investigate the association of PM2.5 with HRV indices. The results showed that decreases in the HRV indices were associated with increased levels of PM2.5. The personal exposure levels to PM2.5 were the highest in the walking mode. The effects of PM2.5 on cardiovascular endpoints were the lowest in the subway mode compared to the effects in the walking mode. The participants in the car and bus modes had reduced effects on their cardiovascular endpoints compared to the participants in the walking mode. We concluded that traffic-related PM2.5 is associated with autonomic alteration. Commuting modes can modify the effects of PM2.5 on HRV indices among young, healthy subjects.

Biomonitoring of blood heavy metals and reproductive hormone level related to low semen quality.

Reproductive hormones and exposure to environmental metals are correlated with low-quality semen. The aim of this study was to evaluate the levels of heavy metals and reproductive hormones in the blood in addition to other relevant factors to clarify the relationship between these factors and semen quality. We recruited 154 male participants from a reproductive medical center. All participants were provided with a questionnaire on lifestyle implementation. The levels of metals in the blood were determined using inductively coupled plasma-mass spectrometry. The levels of hormones in the blood were determined using an automatic gamma counter. Multiple logistic regression analyses were conducted to predict the effects of statistically significant risk factors on semen quality by adjusting for relevant confounders and modifiers. After adjusting for the age, education level, and related factors in the multiple logistic regression analyses, we observed that the increased blood Pb levels were significantly and positively associated with low semen quality. High blood Pb levels (>50 µg/L) had an 11-fold risk of low semen quality. Our results suggest that progressive motility sperm may be a sensitive indicator of the semen quality among all the semen parameters in Taiwan.

Field evaluation of personal sampling methods for multiple bioaerosols.

Ambient bioaerosols are ubiquitous in the daily environment and can affect health in various ways. However, few studies have been conducted to comprehensively evaluate personal bioaerosol exposure in occupational and indoor environments because of the complex composition of bioaerosols and the lack of standardized sampling/analysis methods. We conducted a study to determine the most efficient collection/analysis method for the personal exposure assessment of multiple bioaerosols. The sampling efficiencies of three filters and four samplers were compared. According to our results, polycarbonate (PC) filters had the highest relative efficiency, particularly for bacteria. Side-by-side sampling was conducted to evaluate the three filter samplers (with PC filters) and the NIOSH Personal Bioaerosol Cyclone Sampler. According to the results, the Button Aerosol Sampler and the IOM Inhalable Dust Sampler had the highest relative efficiencies for fungi and bacteria, followed by the NIOSH sampler. Personal sampling was performed in a pig farm to assess occupational bioaerosol exposure and to evaluate the sampling/analysis methods. The Button and IOM samplers yielded a similar performance for personal bioaerosol sampling at the pig farm. However, the Button sampler is more likely to be clogged at high airborne dust concentrations because of its higher flow rate (4 L/min). Therefore, the IOM sampler is a more appropriate choice for performing personal sampling in environments with high dust levels. In summary, the Button and IOM samplers with PC filters are efficient sampling/analysis methods for the personal exposure assessment of multiple bioaerosols.

Pharmacokinetic model of daily selenium intake from contaminated seafood in Taiwan.

Contaminated seafood has been reported as an important source of human exposure to metals in Taiwan. Seafood represents a non-negligible source of selenium in the human diet. This study was designed to determine the concentration of selenium in different types of seafood and predict the concentration of selenium in the blood of Taiwanese using a one-compartment steady-state pharmacokinetic (PK) model. Samples involved three subgroups, including fish, crustaceans and bivalve molluscs. Quantitative analysis for selenium was performed using an ICP-AES (Perkin Elmer) instrument. Selenium concentrations in seafood ranged from 0.63 to 2.01 microg/g wet wt. The highest selenium concentration found in fish was 2.01+/-0.36 microg/g wet wt in Salmo salar Linnaeus. In general, selenium concentration increased in the order of bivalve molluscs

Seroepidemiology of Toxoplasma gondii infection among Chinese aboriginal and Han people residing in mountainous areas of northern Thailand.

A seroepidemiological survey of Toxoplasma gondii infection among Chinese refugees, including Akka and Yau aborigines and Han people living in mountainous areas at elevations of 1,100-1,400 m in Chiang-Rai Province of northern Thailand, was conducted during January 2003 using the latex agglutination test. The overall seroprevalence of T. gondii infection was 9.1% for Akka aborigines, 37.9% for Yau aborigines, and 7.9% for Han people, respectively. No significant gender difference in seroprevalence was found among any of the groups (P > 0.05). The results of a multiple logistic regression analysis for Yau aborigines and Han people showed that the older the age, the higher the odds ratios (OR) of being seropositive (OR = 3.0, 95% confidence interval [CI] = 0.5 to 16.9, P < 0.001 and OR = 1.5, 95% CI = 0.3 to 8.0, P = 0.06 for the elderly group vs. the child group for the Yau aborigines and Han people, respectively). In contrast, the OR was lower among older Akka aboriginal populations (OR = 0.1, 95% CI = 0.0 to 0.4, P < 0.001). Ethnically, Yau aboriginal populations had a significantly higher seroprevalence than did the Akka aborigines and Han people (P < 0.001).

Personal exposure to household particulate matter, household activities and heart rate variability among housewives.

BACKGROUND: The association between indoor air pollution and heart rate variability (HRV) has been well-documented. Little is known about effects of household activities on indoor air quality and HRV alteration. To investigate changes in HRV associated with changes in personal exposure to household particulate matter (PM) and household activities. METHODS: We performed 24-h continuous monitoring of electrocardiography and measured household PM exposure among 50 housewives. The outcome variables were log10-transformed standard deviation of normal-to-normal (NN) intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD). Household PM was measured as the mass concentration of PM with an aerodynamic diameter <2.5 µm (PM2.5). We used mixed-effects models to examine the association between household PM2.5 exposure and log10-transformed HRV indices. RESULTS: After controlling for potential confounders, an interquartile range change in household PM2.5 with 1- to 4-h mean was associated with 1.25-4.31% decreases in SDNN and 0.12-3.71% decreases in r-MSSD. Stir-frying, cleaning with detergent and burning incense may increase household PM2.5 concentrations and modify the effects of household PM2.5 on HRV indices among housewives. CONCLUSIONS: Indoor PM2.5 exposures were associated with decreased SDNN and r-MSSD among housewives, especially during stir-frying, cleaning with detergent and burning incense.