Determinants of residential greenness and its association with prostate cancer risk: A case-control study in Singapore.

BACKGROUND: Exposure to greenness has been shown to be beneficial to health, but few studies have examined the association between residential greenness and prostate cancer (PCa) risk. Our main objectives were to identify the determinants of residential greenness, and to investigate if residential greenness was associated with PCa risk in Singapore. METHODS: The hospital-based case-control study was conducted between April 2007 and May 2009. The Singapore Prostate Cancer Study (SPCS) comprised 240 prostate cancer cases and 268 controls, whose demographics and residential address were collected using questionnaires. Residential greenness was measured by normalized difference vegetation index (NDVI) around the participants' homes using a buffer size of 1 km. Determinants of NDVI were identified using a multivariable linear regression model. Logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of associations between NDVI and PCa risk, adjusting for potential confounders. RESULTS: Having a BMI within the second quartile, as compared to the lowest quartile, was associated with higher levels of NDVI (ß-coefficient = 0.263; 95% CI = 0.040-0.485) after adjusting for covariates. Additionally, being widowed or separated, as compared to being married, was associated with lower levels of NDVI (ß-coefficient = -0.393; 95% CI = -0.723, -0.063). An interquartile range (IQR) increase in NDVI was positively associated with prostate cancer risk OR = 1.45; 95% CI = 1.02-2.07). Stratified analysis by tumour grade and stage showed that higher NDVI was associated with higher risk of low grade PCa. CONCLUSION: Our findings suggested that residential greenness was associated with higher risk of PCa in Singapore. Future studies on the quality and type of green spaces, as well as other factors of residential greenness, in association with PCa risk should be conducted to better understand this relationship.

Photorefractive keratectomy in young Asian aviators with low-moderate myopia.

INTRODUCTION: The high prevalence of myopia among Asians led the Republic of Singapore Air Force (RSAF) to introduce photorefractive keratectomy (PRK) as a means of enlarging its pilot recruitment pool at the end of 2005. This study aims to address the efficacy and safety of PRK performed on young Asian patients with low-moderate myopia, as well as audit the RSAF's corneal refractive surgery (CRS) program. METHODS: This is a retrospective case series of 149 eyes of 76 consecutive patients that underwent PRK as part of the RSAF CRS program over the 5-yr period from 1 January 2006 to 31 December 2010. RESULTS: The median patient age was 21 yr (range, 18-26 yr) and the mean preoperative spherical equivalent (SE) refraction was -3.39 - 1.19 D. Of the patients, 96.1% were men and all were of Asian origin. At the 12-mo follow-up, 98.5% of eyes had an uncorrected distance visual acuity (UDVA) of < or = 0.00 LogMAR, 100.0% of eyes had an SE refraction of within + 0.50 D of intended correction, and 2.300% of eyes had a loss of corrected distance visual acuity (CDVA) of 0.20 LogMAR. The cumulative incidence of retreatments was 6.7% and cumulative incidence of grade II or worse corneal haze requiring retreatment was 6.0%. Refractive stability was achieved at 3 mo postsurgery. CONCLUSION: The results of this study suggest that PRK performed within the context of a stringent and structured CRS program on young Asian eyes with low-moderate myopia is both efficacious and safe, with refractive stability achieved by 3 mo.

Health profile of workers from different industries in Singapore.

Introduction: Workplace safety and health are interrelated - a worker who is not healthy may cause safety lapses at the workplace; conversely, safety lapses could affect the health of the workers. This study was part of a larger Total Workplace Safety and Health (WSH) programme run by the Workplace Safety and Health Council, Singapore. The objectives were to obtain a baseline health profile of workers across four major industries and identify important health risks for targeted workplace interventions. Methods: Five service providers (SPs) were appointed to run the Total WSH programme. As part of the programme, SPs conducted an anonymous basic health survey among workers of participating companies. Results: The responses of 6,373 respondents from the cleaning, construction, manufacturing, and transport and storage industries were studied. The overall response rate was 62%. Key health issues identified were high rates of obesity (22%) and smoking (24%) and low prevalence of regular exercise and healthy dietary habits. Chronic disease rates were similar to population self-reported rates (hypertension 15%, high lipid 12% and diabetes mellitus 6%). The workers reported high work stress (13%). Conclusion: Health issues are prevalent in the workforce and may affect work and employee safety. It is increasingly important for employees' health to be considered in risk assessments and prioritised in workplace safety and health management systems and strategies. Health promotion interventions should be targeted, and multilevel and multicomponent initiatives should be integrated with pre-existing occupational safety programmes.

Association between Vitamin A and E Forms and Prostate Cancer Risk in the Singapore Prostate Cancer Study.

PURPOSE: This study aimed to assess associations between forms of vitamin A and E (both individually and collectively) and the risk of prostate cancer, as well as identify potential effect modifiers. METHODS: Utilizing data from the Singapore Prostate Cancer Study, a hospital-based case-control study, we measured the serum concentrations of 15 different forms of vitamins A and E in 156 prostate cancer patients and 118 control subjects, using a high-performance liquid chromatography technique. These forms included retinol, lutein, zeaxanthin, α-cryptoxanthin, ß-cryptoxanthin, α-carotene, ß-carotene, lycopene, ubiquinone, δ-tocopherol, γ-tocopherol, α-tocopherol, δ-tocotrienol, γ-tocotrienol, and α-tocotrienol. The odds ratio and 95% confidence interval for associations between vitamin A and E and prostate cancer risk were estimated using logistic regression models after adjustment for potential confounders. The analyses were further stratified by smoking and alcohol consumption status. The mixture effect of micronutrient groups was evaluated using weighted quantile sum regression. RESULTS: Higher concentrations of retinol, lutein, α-carotene, ß-carotene, ubiquinone, α-tocopherol, δ-tocotrienol, γ-tocotrienol, and α-tocotrienol were significantly and positively associated with overall prostate cancer risk. Among ever-smokers, associations were stronger for lutein, ß-cryptoxanthin and ß-carotene compared with never-smokers. Among regular alcohol drinkers, associations were stronger for lutein, ß-cryptoxanthin, ubiquinone, γ-tocotrienol and α-tocotrienol compared with non-regular alcohol drinkers. Retinol and α-tocotrienol contributed most to the group indices 'vitamin A and provitamin A carotenoids' and 'vitamin E', respectively. CONCLUSIONS: Several serum vitamin A and E forms were associated with prostate cancer risk, with significant effect modification by smoking and alcohol consumption status. Our findings shed light on prostate cancer etiology.

Sun exposure and risk of lymphoid neoplasms in Singapore.

BACKGROUND: Epidemiologic studies have reported an inverse association between sun exposure and non-Hodgkin lymphoma (NHL), but these have been almost exclusively conducted in Western populations residing in temperate locations. We evaluated the association between personal outdoor sun exposure and risk of malignant lymphomas in Singapore. METHODS: A hospital-based case-control study of 541 incident cases of lymphoid neoplasms and 830 controls were recruited during 2004-2008. Participants were interviewed regarding recreational or occupational outdoor activities during childhood and in adulthood. Basic demographics and potential confounders were also collected. Odds ratios (OR) and 95 % confidence intervals (CI) were calculated using unconditional logistic regression analysis. RESULTS: Compared with individuals who did not have regular sun exposure, a lower risk of NHL was observed for those who reported regular exposure on non-school days during childhood [OR, 0.62; 95 % CI, 0.46-0.83] and non-working days in adulthood [OR, 0.70; 95 % CI, 0.51-0.97]. The protective effect was more evident among women. CONCLUSION: Our findings support an inverse relationship between intermittent sun exposure and the risk of NHL. These findings are consistent with the growing evidence from various countries, but further studies, especially prospective studies, are needed in Asian populations.

A comparative population-based study of prostate cancer incidence and mortality rates in Singapore, Sweden and Geneva, Switzerland from 1973 to 2006.

BACKGROUND: Prostate cancer is the most commonly diagnosed malignancy in men in Sweden and Geneva, and the third most common in men in Singapore. This population-based study describes trends in the incidence and mortality rates of prostate cancer in Singapore, Sweden and Geneva (Switzerland) from 1973 to 2006 and explores possible explanations for these different trends. METHODS: Data from patients diagnosed with prostate cancer were extracted from national cancer registries in Singapore (n = 5,172), Sweden (n = 188,783) and Geneva (n = 5,755) from 1973 to 2006. Trends of incidence and mortality were reported using the Poisson and negative binomial regression models. The age, period and birth-cohort were tested as predictors of incidence and mortality rates of prostate cancer. RESULTS: Incidence rates of prostate cancer increased over all time periods for all three populations. Based on the age-period-cohort analysis, older age and later period of diagnosis were associated with a higher incidence of prostate cancer, whereas older age and earlier period were associated with higher mortality rates for prostate cancer in all three countries. CONCLUSIONS: This study demonstrated an overall increase in incidence rates and decrease in mortality rates in Singapore, Sweden and Geneva. Both incidence and mortality rates were much lower in Singapore. The period effect is a stronger predictor of incidence and mortality of prostate cancer than the birth-cohort effect.

Effect of ageing and body mass index on prostate-specific antigen levels among Chinese men in Singapore from a community-based study.

OBJECTIVE To assess the effect of ageing and body mass index (BMI) on prostate-specific antigen (PSA) among Chinese men from the results of the 2005 Prostate Awareness Week in Singapore. SUBJECTS AND METHODS In all, 2714 men participated in the programme, consisting of 2431 Chinese, 114 Malays, 117 Indians and 52 'others'. Of these, 2410 Chinese men who had a PSA level of <20 ng/mL and were aged >50 years but <80 years were included in the analysis. Height and weight were used to calculate the BMI. The relationship between age and PSA levels was analysed using linear regression and bivariate correlation, and the associations among different groups of BMI and PSA levels were analysed using analysis of variance and covariance. RESULTS PSA levels were significantly correlated with age (correlation coefficient, r = 0.27, P < 0.001). Analyses showed a significant inverse association between PSA level and BMI; mean PSA levels decreased with increasing BMI for both standards (standard classification; geometric mean, GM, PSA of 1.08, 1.06, 0.96, 0.83 ng/mL for a BMI of <18.5, 18.5-24.9, 25-29.9 and > or =30 kg/m(2), respectively, P trend <0.01; and for Asian classification, GM PSA 1.08, 1.09, 0.96, 0.91 ng/mL for a BMI of <18.5, 18.5-22.9, 23-27.5 and > or =27.5, respectively, P trend <0.001). There were significant differences (P < 0.05) in the age-adjusted GM PSA levels for the groups with BMI <25 (1.05 ng/mL) and BMI > or =25 kg/m(2) (0.97 ng/mL). Similarly, there were significant differences (P < 0.05) in the age-adjusted GM PSA levels in those with a BMI of <30 (1.03 ng/mL) and > or =30 kg/m(2) (0.85 ng/mL). CONCLUSION These data suggest that the BMI in Chinese men in Singapore is significantly associated with PSA levels, especially among the obese men aged 70-79 years.

Salivary acetylcholinesterase as a biomarker for organophosphate exposure.

BACKGROUND: Workers exposed to organophosphate (OP) pesticides are required to undergo periodic statutory medical surveillance in several countries. AIM: To study the relationship between serum, erythrocyte and saliva acetylcholinesterase (AChE) levels and to explore the use of salivary AChE as potential biomarker for OP exposure. METHODS: A cross-sectional study was conducted on 19 healthy adult male lead-exposed workers who were undergoing six monthly statutory medical examination. Passive drool saliva samples were collected from each worker. Each blood sample was tested for serum and erythrocyte AChE, and each saliva sample was tested for AChE. RESULTS: Among the 19 subjects, the mean (+/-standard deviation) of salivary, erythrocyte and serum AChE/cholinesterase were 22.7 (+/-17.4), 17171 (+/-1467), 8861 (+/-1876) U/l, respectively. There was a moderate correlation between salivary and erythrocyte AChE (r = 0.42, P = 0.071), but not salivary and serum AChE (r = -0.17, P = 0.48). The level of AChE in saliva was approximately 1820 times lower than AChE in erythrocytes. CONCLUSION: It is probably not feasible to use saliva as a replacement for blood for the measurement of AChE levels. This is because of the much lower levels of AChE in saliva relative to erythrocytes, the weak correlation between the two measurements and the previously reported high intra-individual variation of salivary AChE.

Association between serum heavy metals and prostate cancer risk - A multiple metal analysis.

BACKGROUND: Prostate cancer is one of the most prevalent cancers in men. Exposure to heavy metals and their association with prostate cancer risk has been studied extensively, but combined effects remain largely inconclusive. OBJECTIVES: To elucidate the association between serum concentrations of heavy metals and prostate cancer risk. METHODS: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of a panel of 10 heavy metals (Mn, Cu, Zn, As, Se, Sb, Co, Cu, Cd and Pb) in serum samples of 141 cases and 114 controls in the Singapore Prostate Cancer Study. Linear probit regression models were used to estimate risk differences (RDs) and 95% confidence intervals (CIs) for the associations between log-centered serum metal concentrations and prostate cancer risk with adjustment for potential confounders. Bayesian kernel machine regression (BKMR) models were used to account for nonlinear, interactive, and joint metal effects. RESULTS: Using probit regression, four heavy metals (As, Zn, Mn, Sb) were significantly and positively associated with prostate cancer risk in the unadjusted models. Using BKMR analysis, both As and Zn had positive risk differences on prostate cancer risk when all other metals were held fixed at the 25th and 50th percentiles (RD, 25th percentile: As: 0.15, Zn: 0.19, RD, 50th percentile: As: 0.45, Zn: 0.37). In addition, the overall mixture risk difference was positive and the 95% credible intervals did not include 0 when all metals in the mixture were jointly above their 55th percentile, as compared to when all metals were below their median values. CONCLUSIONS: In summary, we found positive associations between the serum levels of As and Zn and prostate cancer risk on the risk difference scale using BKMR models. The overall mixture effect was also associated with increased prostate cancer risk. Future studies are warranted to validate these findings in prospective studies.

Incidence, mortality and survival patterns of prostate cancer among residents in Singapore from 1968 to 2002.

BACKGROUND: From 1968 to 2002, Singapore experienced an almost four-fold increase in prostate cancer incidence. This paper examines the incidence, mortality and survival patterns for prostate cancer among all residents in Singapore from 1968 to 2002. METHODS: This is a retrospective population-based cohort study including all prostate cancer cases aged over 20 (n = 3613) reported to the Singapore Cancer Registry from 1968 to 2002. Age-standardized incidence, mortality rates and 5-year Relative Survival Ratios (RSRs) were obtained for each 5-year period. Follow-up was ascertained by matching with the National Death Register until 2002. A weighted linear regression was performed on the log-transformed age-standardized incidence and mortality rates over period. RESULTS: The percentage increase in the age-standardized incidence rate per year was 5.0%, 5.6%, 4.0% and 1.9% for all residents, Chinese, Malays and Indians respectively. The percentage increase in age-standardized mortality rate per year was 5.7%, 6.0%, 6.6% and 2.5% for all residents, Chinese, Malays and Indians respectively. When all Singapore residents were considered, the RSRs for prostate cancer were fairly constant across the study period with slight improvement from 1995 onwards among the Chinese. CONCLUSION: Ethnic differences in prostate cancer incidence, mortality and survival patterns were observed. There has been a substantial improvement in RSRs since the 1990s for the Chinese.

A cross-sectional study of primary-care physicians in Singapore on their concerns and preparedness for an avian influenza outbreak.

INTRODUCTION: During an avian influenza (AI) pandemic, primary-care physicians (PCPs) are expected to play key roles in the prevention and control of the disease. Different groups of PCPs could have different concerns and preparedness level. We assessed the concerns, perceived impact and preparedness for an outbreak among PCPs in Singapore. MATERIALS AND METHODS: A cross-sectional survey of PCPs working in private practice (n=200) and public clinics (n=205) from March to June 2006 with an anonymous self-administered questionnaire on concerns (12- items), perceived impact (10 items) and preparedness (10 items) for an outbreak. RESULTS: Two hundred and eighty-five PCPs responded - 149 (response rate: 72.7%) public and 136 (response rate: 67.3%) private. The majority were concerned about risk to their health from their occupation (95.0%) and falling ill with AI (89.7%). Most (82.5%) accepted the risk and only 33 (11.8%) would consider stopping work. For perceived impact, most felt that people would avoid them (69.6%) and their families (54.1%). The majority (81.3%) expected an increased workload and feeling more stressed at work (86.9%). For preparedness, 78.7% felt personally prepared for an outbreak. Public PCPs were more likely to be involved in infection-control activities and felt that their workplaces were prepared. CONCLUSIONS: Most PCPs felt personally prepared for an outbreak but were concerned about their exposure to AI and falling ill. Other concerns included social ostracism for themselves and their families. Public PCPs appeared to have a higher level of preparation. Addressing concerns and improving level of preparedness are crucial to strengthen the primary-care response for any AI outbreak.

Concerns, perceived impact and preparedness in an avian influenza pandemic--a comparative study between healthcare workers in primary and tertiary care.

INTRODUCTION: With the potential threat of an avian influenza (AI) pandemic, healthcare workers (HCWs) are expected to play important roles, and they encounter significant stress levels from an expected increase in workload. We compared the concerns, perceived impact and preparedness for an AI pandemic between HCWs working in public primary care clinics and a tertiary healthcare setting. MATERIALS AND METHODS: An anonymous, self-administered questionnaire was given to 2459 HCWs working at 18 public polyclinics (PCs) and a tertiary hospital (TH) in Singapore from March to June 2006. The questionnaire assessed work-related and non-work-related concerns, perceived impact on personal life and work as well as workplace preparedness. RESULTS: We obtained responses from 986 PC and 873 TH HCWs (response rate: 74.6% and 76.7%). The majority in both groups were concerned about the high AI risk from their occupation (82.7%) and falling ill with AI (75.9%). 71.9% accepted the risk but 25.5% felt that they should not be looking after AI patients with 15.0% consider resigning. HCWs also felt that people would avoid them (63.5%) and their families (54.1%) during a pandemic. The majority expected an increased workload and to feel more stressed at work. For preparedness, 74.2% felt personally prepared and 83.7% felt that their workplaces were prepared for an outbreak. TH HCWs were more likely to be involved in infection-control activities but the perception of infection-control preparedness in both groups was high (>80.0%). CONCLUSIONS: HCWs in both public primary and tertiary healthcare settings felt prepared, personally and in their workplaces, for a pandemic. Their main concerns were risks of falling ill from exposure and the possibility of social ostracism of themselves and their families. Preparedness levels appeared high in the majority of HCWs. However, concerns of HCWs could affect their overall effectiveness in a pandemic and should be addressed by incorporating strategies to manage them in pandemic planning.

Comfort and exertion while using filtering facepiece respirators with exhalation valve and an active venting system among male military personnel.

INTRODUCTION: This study aimed to determine if disposable filtering facepiece respirators (FFRs) that come with an exhalation valve (EV) and a novel active venting system (AVS) provided greater perceived comfort and exertion when compared to standard N95 FFRs without these features among male military personnel performing prolonged essential outdoor duties. METHODS: We used a randomised open-label controlled crossover study design to compare three FFR options: (a) standard FFR; (b) FFR with EV; and (c) FFR with EV+AVS. Male military personnel aged between 18 and 20 years completed a questionnaire at the start of outdoor duty (baseline), after two hours of standardised non-strenuous outdoor duty and after 12 hours of duty divided into two-hour work-rest cycles. Participants rated the degree of discomfort, exertion and symptoms using a five-point Likert scale. The association between outcomes and types of FFR was assessed using a multivariate ordered probit mixed-effects model. RESULTS: For a majority of the symptoms, study participants gave FFR with EV and FFR EV+AVS significantly better scores than standard FFR. Both FFR with EV and FFR with EV+AVS had significantly less discomfort (FFR with EV+AVS: 91.1%; FFR with EV: 57.6%) and exertion (FFR with EV+AVS: 83.5%; FFR with EV: 34.4%) than standard FFR. FFR with EV+AVS also had significantly better scores for exertion (53.4%) and comfort (39.4%) when compared to FFR with EV. CONCLUSION: Usage of FFR with EV+AVS resulted in significantly reduced symptoms, discomfort and exertion when compared to FFR with EV and standard FFR.

Comparison of hepatic and serum lipid signatures in hepatocellular carcinoma patients leads to the discovery of diagnostic and prognostic biomarkers.

We compared hepatic and serum lipid changes in hepatocellular carcinoma (HCC) patients to have a better understanding of the molecular pathogenesis of this disease and discovery novel lipid biomarkers. Hepatic and serum lipid profiling was conducted in paired liver and serum samples from 50 HCC patients and 24 healthy controls. A total of 20 hepatic and 40 serum lipid signatures were identified, yet there was hardly any significant correlation between them. The results indicated that triglycerides and phosphatidylcholines contributed significantly to altered hepatic lipids, whereas triglycerides and phosphatidylethanolamine-based plasmalogens (PEp) contributed most to altered serum lipids. In serum, PEp (36:4) and (40:6) showed a fair capability to discriminate HCC patients from healthy controls, and were significantly associated with HCC tumor grades (p < 0.05), and thus were identified as potential diagnostic and prognostic biomarkers of HCC. These findings were confirmed by a validation study conducted in an independent cohort consisting of 18 HCC, 20 cirrhosis patients, and 20 healthy controls. This study suggests that hepatic and serum lipid signatures of HCC have to be considered as mostly independent, and the results imply potential roles of PEp species, particularly PEp (36:4) and (40:6), as serum biomarkers for HCC diagnosis and progression.

Possibilities of newer ALAD polymorphism influencing human susceptibility to effects of inorganic lead on the neurobehavioral functions.

OBJECTIVE: A cross-sectional study was conducted to study the association between some new ALAD polymorphism and susceptibility to effects of inorganic lead on the neurobehavioral functions. METHOD: We recruited 120 healthy male workers with lead exposure in a factory which manufacture lead stabilizer. The ALAD SNPs studied were HpyCH4, HpyIV RFLP in intron 6, Rsa and Msp RFLP in exon 4, Sau3A in intron 12 and Rsa39488 in exon 5. The World Health Organization Neurobehavioral Core Test Battery (WHO-NCTB) and a few other tests were used. General linear model (GLM) was applied to compare outcome scores between subgroups of each ALAD SNP while controlling for possible confounders. RESULTS: The mean age of the workers was 39.7 years (S.D. 10.7), mean exposure duration of 10.2 years (S.D. 7.9) and mean blood lead of 22.1 microg/dl (S.D. 9.4). Among the 6 SNPs studied, Rsa and Rsa39488 appear to be the main candidate SNPs. Workers with Rsa and Rsa39488 ALAD 2-2 genotypes fare significantly better in the Aiming Pursue Test Correct (AC), Groove Peg Board non-preferred hand (GPNP), Groove Peg Board Mean (GPM), San Ana Preferred Hand (SAP), San Ana Both Hands (SAB) and AC, GPNH, GPM, Digit Symbol (DIS) tests; respectively compared to Rsa and Rsa39488 ALAD 1-1/1-2 genotypes adjusted for age, race, exposure duration and blood lead levels. CONCLUSION: The presence of the homozygote Rsa and Rsa39488 ALAD 2-2 seems to offer some protection against the effect of lead on motor dexterity function. While it may appear that newer ALAD polymorphism other than the commonly reported Msp SNP might influence human susceptibility to effects of inorganic lead on the neurobehavioral functions further study involving a larger cohort of workers with Rsa and Rsa39488 ALAD2 allele would be needed to confirm this inference.

Association of blood lead and homocysteine levels among lead exposed subjects in Vietnam and Singapore.

OBJECTIVES: Lead and homocysteine are both linked to cardiovascular disease. With this in mind, the authors evaluated the relation between blood lead and homocysteine in people aged 19-66 years in two Asian populations. METHODS: This cross-sectional study comprised 183 workers from a lead stabiliser factory in Singapore and 323 workers from a battery factory in Vietnam. Workers were occupationally exposed to lead. Blood lead was analysed using atomic absorption spectrophotometry while plasma homocysteine was measured using high performance liquid chromatography. RESULTS: Chinese subjects had the lowest blood lead levels while the Indians had the highest. Controlling for age, sex and race, an increase of 1 microg/dl in blood lead was associated with an increase of 0.04 micromol/l of homocysteine on the log scale. Gender and ethnicity seemed to be strongly associated with the relation between lead and homocysteine. The positive relation between lead and homocysteine among the Vietnamese subjects was significant (Pearson's r = 0.254, p<0.01). When blood lead levels were divided by quartiles, the correlation coefficient between blood lead levels in the 4th quartile and homocysteine among the Vietnamese was higher (r = 0.405, p<0.01). Overall, an increase of 1 microg/dl in blood lead in all the Vietnamese subjects was associated with an increase of 0.05 micromol/l increase in homocysteine on the log scale. However, in the 4th quartile, the same increase was associated with an increase of 0.41 micromol/l of homocysteine on the log scale. CONCLUSIONS: Blood lead was found to be associated with homocysteine levels in this Asian sample. Although we cannot determine causality from cross-sectional data, it is sensible to consider the probability that this relation could explain one of the mechanisms of the impact of lead on the cardiovascular system. More studies would be needed to confirm this inference.

Prostate-specific antigen levels among Chinese, Malays and Indians in Singapore from a community-based study.

The purpose of this study was to examine the distribution of prostate-specific antigen levels among Chinese, Malays and Indians in Singapore, taking the effect of age into consideration. The study was carried out as part of the Singapore Prostate Awareness Week from 23-26th February 2004. Men above 50 years old went to four government-restructured hospitals to participate in the study. Participants filled up a questionnaire and provided 5 ml of blood for measurement of PSA levels using the Abbott IMx Total PSA assay (Abbott Laboratories). 3,486 men responded to the study, comprising 92.8% Chinese, 3.0% Malays, 2.5% Indians and 1.8% Others. 92.7% of them had PSA levels of 4 microg/L or less. There were no significant differences (p<0.05) between the mean PSA levels of Chinese (1.60 microg/L), Malays (1.39 microg/L), Indians (1.23 microg/L) and Others (1.70 microg/L). PSA levels were significantly associated with age (Spearman's r= 0.27, p<0.01). PSA levels increased with each 10-year age group and these trends were significant (p<0.0001) across both PSA group levels and age groupings. In the 50-60 years age groups, the prevalence of PSA levels >4 mug/L were 1.1% and 3.7% respectively. This rose rapidly to 11.3% and 23.5% for age groups >60-70 and >80 years respectively. Our study shows that the median PSA levels in the Caucasian population in the USA are higher than those of Chinese, Malays and Indians in Singapore. PSA levels were positively associated with age. It may be more appropriate to offer PSA testing to men who are >60 years old rather than the current >50 years.

Concerns and preparedness for an avian influenza pandemic: a comparison between community hospital and tertiary hospital healthcare workers.

Little is known about differences in levels of concerns or preparedness for an avian influenza (AI) pandemic among healthcare workers (HCWs) in different types of hospitals. We compared these concerns and preparedness between 326 HCWs of two community hospitals (CHs) and 908 HCWs from a tertiary hospital (TH) using a self-administered questionnaire between March-June 2006. Response rates were 84.2% and 80.0% from the CHs and TH. Most HCWs (71.6%) felt prepared for an AI outbreak and had significant concerns. They perceive an AI pandemic having adverse impacts on their personal life and work, such as people avoiding them (57.1%). A greater percentage of TH compared to CH HCWs expressed concerns such as feeling their jobs put them at great AI exposure (78.3% vs 67.5%, p=0.012). TH HCWs were more likely to report participating in readiness preparation activities, such as training for infection control (90.0% vs 82.2%, p=0.014) and feel that they (74.1% vs 64.7%, p=0.045) and their hospital (86.8% vs 71.8%, p=0.000) were prepared for an outbreak. Healthcare institutions need to include personal, psychological and family concerns on the agenda and increase participation in readiness preparation activities among HCWs to help prepare for such future crises.

Associations of serum organohalogen levels and prostate cancer risk: Results from a case-control study in Singapore.

There is increasing evidence that elevated exposure to organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) may lead to an increased risk of prostate cancer. As part of a hospital-based case-control study of the Singaporean male population, we investigated associations between organohalogen exposure and risk of prostate cancer. Trace residue concentrations of 74 organohalogen contaminants, including several PCBs, OCPs and halogenated flame retardants (HFRs), were determined in serum samples (n = 120) using gas chromatography tandem mass spectrometry (GC-MS/MS). A variety of OCPs, PCBs and HFRs were detected in samples of both patients and controls. Mean concentrations of p,p' DDT, p,p' DDE, PCB 118, PCB 138, PCB 153 and PCB 187 were significantly higher (p < 0.05) in serum of patients. p,p' DDE measured in serum of patients was relatively high (mean:13,700 ng/g lipid, 95% CI:7000-26,800). Odds ratios (ORs) of OCPs and PCBs in many cases exceeded 1. ORs for p,p' DDE and PCB-153 at the highest tertile (>67th) were 5.67 (95% CI, 2.37-13.54) and 2.14 (95% CI, 0.99 to 4.66), respectively. The results suggest that exposure to DDTs and PCBs may be associated with prostate cancer risk in Singaporean males. No such association was observed for the organohalogen flame retardants studied, including polybrominated diphenyl ethers (PBDEs). The study provides novel information regarding the occurrence, levels and potential associations with prostate cancer risk for several organohalogen contaminants in the Singapore population. However, further investigation and analyses should be conducted to confirm these findings.

Possible influence of delta-aminolevulinic acid dehydratase polymorphism and susceptibility to renal toxicity of lead: a study of a Vietnamese population.

We examined six newly identified polymorphisms in the delta-aminolevulinic acid dehydratase (ALAD) single-nucleotide polymorphisms (SNPs) to determine if these SNPs could modify the relationship between blood lead (PbB) and some renal parameters. This is a cross-sectional study of 276 lead-exposed workers in Vietnam. All workers were measured for PbB, urinary retinol-binding protein (URBP), urinary alpha1-microglobulin (Ualpha1m), urinary beta2-microglobulin (Ubeta 2m), urinary N-acetyl-beta -d-glucosaminidase (NAG), urinary aminolevulinic acid (ALAU), serum alpha1-microglobulin (Salpha1m), serum beta2-microglobulin (Sbeta 2m), and urinary albumin (Ualb). The six SNPs were Msp and Rsa in exon 4, Rsa39488 in exon 5, HpyIV and HpyCH4 in intron 6, and Sau3A in intron 12. Analysis of covariance (ANCOVA) with interaction of PbB times SNPs were applied to examine modifying effect of the SNPs on the association of renal parameters and PbB, adjusting for potential confounders of age, gender, body mass index, and exposure duration. HpyCH4 was found to be associated with certain renal parameters. For HpyCH4 1-1, an increase of 1 microg/dL PbB caused an increase of 1.042 mg/g creatinine (Cr) U alpha1m, 1.069 mg/g Cr Ubeta 2m, 1.038 mg/g Cr URBP, and 1.033 mg/g Cr Ualb, whereas in HpyCH4 1-2, an increase of 1 microg/dL PbB resulted in an increase of only 1.009 mg/g Cr Ualpha1m, 1.012 mg/g Cr Ubeta 2m, 1.009 mg/g Cr URBP, and 1.007 mg/g Cr Ualb. HpyCH4 SNP appeared to modify the lead toxicity to kidney with wild-type allele being more susceptible than variants. The mechanism for this effect is not clear. Further studies are needed to confirm this observation.