Heavy metals in private car dusts collected from Universiti Malaysia Pahang, Gambang Campus: Contamination and human health risks

A pilot study was conducted to investigate the concentrations of seven heavy metals (Zn, Cu, Cr, Cd, Fe, Ni and Pb) in private car dusts collected from Universiti Malaysia Pahang (UMP), Gambang campus. Ten private cars were selected among UMP staffs and students, and the dust samples were obtained by using a conventional vacuum cleaner with a clean nylon sampling sock pre-inserted into the suction nozzle. All samples were acid-digested with aqua regia solution and analysed for metal concentration using Atomic Absorption Spectrometry (AAS). The highest mean concentrations were recorded for Fe (650± 480 mg/kg), followed by Zn (160 ± 110 mg/kg), Cu (76.2 ± 18.5 mg/kg), Pb (39.2 ± 99.1 mg/kg), Ni (6.39 ± 8.30 mg/kg), Cr (3.42 ± 5.90 mg/kg) and Cd (0.55 ± 1.40 mg/kg). Hazard quotient (HQ) and hazard index (HI) values lower than 1 indicated no potential non-carcinogenic risks to the adult drivers

Trace elements in market vegetables of Kuantan, Pahang: A preliminary estimate of dietary exposure

A pilot study was conducted to investigate the concentrations of ten trace elements: Copper (Cu), iodine (I), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) in nine ready-to-eat market vegetables collected from Kuantan, Pahang. Samples of vegetables were obtained from a local market, acid-digested using open digestion method and then analysed for elements using Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The mean concentration of essential elements decreased in the following order: Mn>Zn>Mo>Cu>I>Ni>Se, with individual concentrations ranging from below detection limit (bdl) to 207 mg/kg dw. Cadmium, a non-essential element, was detected in 8 samples at a mean concentration of 0.06 mg/kg dw, while Pb and As were not detected (bdl) in all samples. The estimated daily dietary intake (EDI) as well as the potential health risk associated with vegetable consumption were calculated. Hazard quotient (HQ) values less than one were obtained for both children and adults, indicating that consumption of these vegetables poses low risk to health

Dematel digraph: A decision making tool for project practitioners and researchers during covid-19 pandemic

DEMATEL DIGRAPH is a new invention that generates directed graph (Digraph) based on DEMATEL (Decision Making Trial and Evaluation Laboratory) algorithm. Helps students and project practitioners in solving complex decision problems, identifying critical risks and analyzing causeeffect chain components of a complex system

Heavy metal in different size fractions of household dust collected from rural residential area of Simpang Renggam, Johor

A study investigating the levels of selected heavy metals in household dust from a rural residential area was carried out. Household dust was collected from seven residential homes within the area of Simpang Renggam, Johor. All samples were sieved through a 200 μm sieve, in which two dust samples with sufficient masses (sample A and B) were further separated into four discrete fractions (<63 μm, 63-75 μm, 75-150 μm, and 150-200 μm) before analysis. Dust samples were acid digested and analyzed for the content of Al, Cr, Mn, Ni, Zn, Cu, Cd, Ba, Pb, Mg, and Fe using inductively coupled plasma - mass spectrometer (ICP-MS). Results showed that the Fe and Al were among the most abundant elements in bulk dust samples (mean concentration of 8500 mg/kg and 5100 mg/kg, respectively), and their concentrations increased with decreasing particle size. Mean concentrations of other elements ranged between 0.027 mg/kg to 2310 mg/kg. For Mn, Mg, Cu, and Zn, higher levels were measured in coarser particle size. Health risk estimation indicated that Hazard Quotient (HQ) and Hazard Index (HI) values were below than 1, representing no noncarcinogenic risk to the residents via ingestion, inhalation, and dermal absorption

Spatial and temporal trends of polycyclic aromatic hydrocarbons in sediment cores of Brunei Bay, East Malaysia

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in three sediment cores from Brunei Bay, Southern South China Sea was investigated. The total concentrations of 16 priority PAHs (∑PAH16) and their alkyl-substituted derivatives ranged from 10.4 to 376 ng g−1 and 30.7 to 2263 ng g−1, respectively. PAH biomarker diagnostic ratios and principal component analysis (PCA) combined with absolute principal component score (APCS) and multiple linear regression (MLR) were performed to apportion the source contribution. The results revealed mixed inputs of fuel combustion residues and uncombusted petrogenic products. The downcore PAH profile revealed that the highest peaks could be related to past human activities using biofuel and coal during the industrialization/agriculture revolution period. The 1,7/(2,6+1,7)-dimethylphenanthrene ratio also highlighted wood combustion during forest fire outbreaks, which appeared to coincide with the past climate events

Critical Risk Factors in Construction Projects: A Dematel-Based Model

Construction projects are defenceless to more risks compared to the other industries due to their nature and complexities. These risks can lead to performance reductions, increased costs, scheduling delays, and even project failure. It is noted that the success of the project depends on identifying the most common risk factors and mitigate them effectively. Numerous studies have discussed the significance of investigating the critical risks in the construction projects but the complex causal relationships among the risk factors and their relative significance with respect to each other remain unexplored. The purpose of this paper is to identify the critical risk factors and investigate the interrelationship among the risk factors in the construction projects. Detailed literature review has been conducted and ten risk factors were identified. Decision Making Trial and Evaluation Laboratory (DEMATEL) is employed in the study to prioritize the risks and then analyse the causal relationship among the factors. Based on the interview data from thirteen experts, the results show design risks are the critical risk factors. The findings in this study can provide structural visualization of complex causal relationships among risk factors and also allow construction experts to prioritize the resource allocation to achieve project objectives. Keywords: Construction Industry; Critical Risks; Decision Making Trial & Evaluation Laboratory (DEMATEL)

Dietary Intake Contributed the Most to Chlorinated Paraffin Body Burden in a Norwegian Cohort

Determining the major human exposure pathways is a prerequisite for the development of effective management strategies for environmental pollutants such as chlorinated paraffins (CPs). As a first step, the internal and external exposure to CPs were quantified for a well-defined human cohort. CPs in participants' plasma and diet samples were analyzed in the present study, and previous results on paired air, dust, and hand wipe samples were used for the total exposure assessment. Both one compartment pharmacokinetic modeling and forensic fingerprinting indicate that dietary intake contributed the most to body burden of CPs in this cohort, contributing a median of 60-88% of the total daily intakes. The contribution from dust ingestion and dermal exposure was greater for the intake of long-chain CPs (LCCPs) than short-chain CPs (SCCPs), while the contribution from inhalation was greater for the intake of SCCPs than medium-chain CPs (MCCPs) and LCCPs. Significantly higher concentrations of SCCPs and MCCPs were observed in diets containing butter and eggs, respectively (p < 0.05). Additionally, other exposure sources were correlated to plasma levels of CPs, including residence construction parameters such as the construction year (p < 0.05). This human exposure to CPs is not a local case. From a global perspective, there are major knowledge gaps in biomonitoring and exposure data for CPs from regions other than China and European countries

Analysis of illicit drugs in municipal wastewater using LCMS/MS: A method validation study

An analytical method based on solid-phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of five illicit drugs, namely amphetamine (AM), methamphetamine (MA), 3,4- methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and morphine (MOR) in municipal wastewater has been optimized and validated. Sample preparation was performed using Oasis MCX SPE cartridges. LC separation was performed using a Zorbax Eclipse Plus C18 RRHD column. The linearity of the calibration curve was between 5 ng/mL and 250 ng/mL, with determination coefficient (R2 ) greater than 0.99, except for morphine. The mean recoveries of target analytes ranged from 91.6 to 112%, and the method demonstrated good inter-day repeatability (coefficient of variation, CV ranged from 2 to 19%). The limit of detection (LOD) for AM, MA, MDMA, MDA, and MOR was 0.29, 0.37, 0.86, 1.09 and 7.56 ng/mL, respectively. The method was applied to municipal wastewater samples collected from sewage treatment plants in Kuantan, Pahang, in which AM, MA and MDA were detected in all 3 samples

THE DIMINISHING RELEVANCE OF DEPARTMENT STORES IN SINGAPORE: CAN DEPARTMENT STORES STILL SERVE AS A CROWD PULLER TO THE MALL?

Bachelor'sBACHELOR OF SCIENCE (REAL ESTATE

What contributes to human body burdens of halogenated flame retardants? : An experimental approach

Flame retardants (FRs) are chemicals added to a broad range of consumer products such as textiles, electrical and electronic equipment, furniture and building material to meet flammability requirements. Most of these chemicals are additives that can continuously leach out from the applied products during usage. FRs are studied because of their abundance in indoor environments and concerns about their impact on human health. The restrictions on many brominated FRs have resulted in a need for their replacement with a variety of emerging halogenated FRs (EHFRs). Humans are exposed to these chemicals mainly through dust and diet ingestion, but there is still insufficient data about the relative importance of other exposure pathways. In this thesis, a Norwegian cohort of 61 adults (age 20-66, 16 males and 45 females) was studied for their exposure to legacy and emerging HFRs. Duplicate diet, stationary air, personal air, settled dust, hand wipe and serum samples were collected from the participants and analyzed for polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs) and EHFRs. External exposures via dietary intake, air inhalation, dust ingestion and dermal exposure (in pg/kg body weight/day) were estimated from the measured concentrations. The intake values were then compared to elucidate which of these exposure pathways were most important for the Norwegian cohorts’ exposure to specific HFRs. Dietary intake was the predominant exposure route for most of the PBDE congeners and EHFRs, whereas dust ingestion contributed significantly to the exposure of some less volatile HFRs. Inhalation exposure was negligible for most of the target HFRs except for those with higher volatility, such as tetrabromoethylcyclohexane (DBE-DBCH), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE) and 1,2,3,4,5-pentabromobenzene (PBBz). Dermal exposure seems to be a significant exposure pathway for HBCDDs and tetrabromobisphenol A (TBBPA) but the relevance of hand wipes to represent total dermal exposure remains uncertain. Overall, the median and 95th percentile total intakes for all target HFRs did not exceed the regulatory reference doses (RfD). Estimated serum concentrations were calculated from total intakes from all exposure pathways using a one compartment pharmacokinetic model and these were compared to measured concentrations. The estimated median serum BDE-47 and BDE-153 concentrations were slightly over-estimated by a factor of 5.5 and 4.3, respectively whereas BDE-197 and -209 were under-estimated by 1 to 2 orders of magnitude compared to the measured concentrations. Statistical analysis suggested that age, number of electronic equipment at home, certain dietary habits, hand washing and house cleaning frequency were possible contributors to HFR exposure.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p