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The establishment of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is one of the global initiatives to promote effective chemical hazard communication worldwide. ...

This investigation quantified spatial variability of heavy metals and followed methods of the U.S. Environmental Protection Agency (EPA) to estimate the hazard indices as well as cancer risks associated with consuming fish caught in the waters of the Langat river basin area, Malaysia. The calculation of metal pollution index (MPI) was carried out to classify the study area according to the level of contamination and the order of stations from highest to lowest MPI values was Langat river > Cempaka lake > Engineering pond > Pond B > Pond A > Jugra > Bandar. The level of exposure due to the consumption of each chemical in Tilapia fish tissue was estimated in an average daily dose equation. The calculated HI ranging from 0.24 to 1.88 indicated 71% stations were in the risk level. Potential carcinogenic risks associated with the ingestion of heavy metals in Tilapia fish were evaluated probabilistically by performing 10,000 trials for Monte Carlo simulation. Cancer risk calculations exceeding the U.S. EPA’s acceptable risk level of 1 in 1,000,000 (or 10-6) included Ni (7.3×10-4) and Cd (2.1×10-6). However, the average carcinogenic risk (2.4×10-4) exceeded the accepted risk level to a great extent. The recommended daily ingestion rate of Tilapia for Malaysian people inhabiting Langat river basin area was calculated considering 95th percentile TR value of 10-6 as an acceptable risk where it is revealed that consumption of Tilapia should be reduced about 67% from the current level to have an acceptable risk of cancer.

Awareness of both chemical safety and chemical security is important in order to avoid or reduce any adverse effects of chemical use; hence, both these topics should be incorporated into the educat...

An optical biosensor employing immobilized haloalkane dehalogenase (HLD), the halide degrading enzyme for the detection of halogenated organic in environmental water and drinking water samples was developed. The enzymatic biosensor was fabricated by incorporating H+ ion selective chromoionophore ETH5294 and HLD enzyme in a stacked chitosan films system on a glass slide. Hydrolytic dehalogenation of dichloroethane (DCA) by the carbon-halide degrading HLD enzyme resulting in the release of a halogen, a proton and a primary alcohol. The halocarbon concentration was optically transduced by the pH transducer layer as a result of protonation reaction of the chromoionophore pH indicator dye embedded in the underneath layer. The resulting colour change of the protonated chromoionophore was measured by fiber optic reflectance spectrophotometry method. Under optimized conditions the detection limit of the proposed reflectance-based enzymatic biosensor membrane was estimated to be 1 mg L−1 with a wide dynamic linear concentration range of 5–60 mg L−1 DCA (R2 = 0.9792) and satisfactory reproducibility within the relative standard deviation (RSD) range of 3.4–4.3%. Validation test demonstrated that the optical halocarbon biosensor could be a promising tool for rapid (6 min) in situ and direct evaluation of organohalide in river water, tap water and bottled water samples without any sample pre-treatment or extraction steps.

A reflectometric biosensor for enzymatic determination of halogenated organic pollutant in environmental water sample was developed. Polyacrylate microspheres modified with succinimide functional groups were employed as the substrate matrix for covalent immobilization of haloalkane dehalogenase (DhlA) enzyme, and ETH5294 Nile Blue chromoionophore (NBC) pH dye was physically immobilized on the acrylic micromatrix to function as an optical proton sensor. The hydrolytic dehalogenation of halocarbon catalyzed by the immobilized DhlA resulting in the release of a halogen and a proton, which protonated the immobilized NBC proton indicator, and a colour change of the biosensor from violet to blue was measured with a reflectance spectrophotometer for indirect quantification of the halogenated hydrocarbon concentration. The enzymatic halocarbon reflectance biosensor exhibited a dynamic linear response range of 1–30 mg L−1 1,2-dichloroethane (DCA) (R2 = 0.9762) with a detection limit of 0.3 mg L−1. The proposed enzymatic biosensor gave rapid response, within 2 min, towards the detection of 50 mg L−1 DCA at 662 nm, and demonstrated stable response up to 6 days of storage period at 4 °C and pH 8.0. Validation between the developed biosensor with standard gas chromatography–electron capture detector (GC-ECD) showed that both methods have a comparable accuracy in detecting halocarbon species.

Exposure to aluminium (Al) is inevitable in the daily life because of its abundance in the environmental media through natural processes. Meanwhile, several studies have reported a positive association between Alzheimer’s disease and a higher level of Al ingestion through drinking water. The present study is the first of its kind in Malaysia which predicts the human health risk of Al ingestion via drinking water at the Langat River Basin, Malaysia. Water samples were collected during 2015–2016 from the four stages of drinking water supply chain at the basin to determine the concentrations of Al by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The determined mean concentration of Al in river 2.50E−01 ± 1.89E−01 mg/L crossed the Malaysian drinking water quality standard of 0.2 mg/L. The higher concentration of Al in the Langat River might be due to natural weathering of Al-bearing minerals. The mean Al concentrations in the treated water by the treatment plants, household’s tap and after filtration water, respectively, were found to be within the Malaysian drinking water quality standard. This study suggests that there is no potential human health risk of Al ingestion through drinking water (HQ = 3.81E−03 ± 1.82E−03) at 95% confidence level in the basin because the hazard quotient (HQ) value is less than 1. However, the authorities need to be careful of excessive ingestion of Al via drinking water because the water treatment plants in the basin follow the conventional method to treat raw water. The turbidity in the tropical Langat River changes very frequently; thus, the doses of Al2(SO4)3 for water disinfection are very crucial. Therefore, reverse osmosis technology can be introduced in the treatment plants because the United States Environmental Protection Agency has recommended that it can remove all types of metal > 90% from treated water.

Abundant of preparatory works have recognized that fluorescent sensors based on 8-aminoquinoline are popular tools to detect Zn2+ ions in environmental and biological applications. Along with these studies, researchers started to introduce a variety of carboxamido group into an 8-aminoquinoline molecule in forming 8-amidoquinoline derivatives. Therefore, this systematic review aims to introduce a general overview of the fluorophore 8-aminoquinoline as Zn2+ receptors and to provide comparisons of collected studies that related to 8-amidoquinoline derivatives as fluorophore probe of the sensor. According to PRISMA systematic searches strategy, 13 articles were analyzed for trends, research designs, results and discussion, subject samples, and remarks or conclusions. We found cross-sectional studies with four aspects in zinc sensing that have been targeted; binding studies via titration, detection's limit, interferences studies, and validation of the study. Hence, this paper also included assessments of those criteria and the trends of development of 8-amidoquinoline derivatives based-zinc fluorescent chemosensor. It also showed that most of the researches conducted in China. In conclusion, this study identified various research designs of fluorescent chemosensors based on 8-amidoquinoline prolong with the effectiveness and potential as a recognition probe to assist the detection of zinc. Hence, elucidation of those derivatives essential to be explored because more studies are needed to improve the sensing criteria of the zinc sensor

Prolonged persistence of toxic cadmium (Cd), chromium (Cr) and lead (Pb) in the aquatic environment are due to its nonbiodegradable characteristic. A few studies have reported higher concentrations of these metals in the transboundary Langat River, Malaysia. This study determined the spatial and temporal distributions of Cd, Cr and Pb concentrations (2005&ndash, 2015) in the Langat River along with assessing the status of these metals in the drinking water supply chain at the basin. Water samples were collected once in 2015 from the drinking water supply chain, i.e., from the river, treated water at plants, taps and filtration water at households. Determined mean concentrations of Cd, Cr and Pb by inductively coupled plasma mass spectrometry in the Langat River were within the drinking water quality standard of Malaysia and the WHO, except for the Pb (9.99 &plusmn, 1.40 &micro, g/L) concentration, which was at the maximum limit, 10 &micro, g/L. The spatial and temporal distribution of these metals&rsquo, concentrations indicate dilution of it downstream, along with the increasing trend in rainfall and water flow, especially during the northeast monsoon. Significant correlation and regression analysis of the Cd, Cr and Pb concentrations also indicate that the sources of this metal pollution are mainly the natural weathering of minerals along with anthropogenic activities in the basin. The determined overall water quality of the Langat River is categorized Class IIA (i.e., clean), which requires conventional treatment before drinking, however, the maximum removal efficiency of these metals by the plants at the basin was about 90.17%. Therefore, the proactive leadership roles of the local authorities will be appropriate to reduce the pollution of this river as well as introducing a two-layer water filtration system at the Langat River Basin to accelerate the achievement of a sustainable drinking water supply.

A DNA micro-optode for dengue virus detection was developed based on the sandwich hybridization strategy of DNAs on succinimide-functionalized poly(n-butyl acrylate) (poly(nBA-NAS)) microspheres. Gold nanoparticles (AuNPs) with an average diameter of ~20 nm were synthesized using a centrifugation-based method and adsorbed on the submicrometer-sized polyelectrolyte-coated poly(styrene-co-acrylic acid) (PSA) latex particles via an electrostatic method. The AuNP&ndash, latex spheres were attached to the thiolated reporter probe (rDNA) by Au&ndash, thiol binding to functionalize as an optical gold&ndash, latex&ndash, rDNA label. The one-step sandwich hybridization recognition involved a pair of a DNA probe, i.e., capture probe (pDNA), and AuNP&ndash, PSA reporter label that flanked the target DNA (complementary DNA (cDNA)). The concentration of dengue virus cDNA was optically transduced by immobilized AuNP&ndash, PSA&ndash, rDNA conjugates as the DNA micro-optode exhibited a violet hue upon the DNA sandwich hybridization reaction, which could be monitored by a fiber-optic reflectance spectrophotometer at 637 nm. The optical genosensor showed a linear reflectance response over a wide cDNA concentration range from 1.0 &times, 10&minus, 21 M to 1.0 &times, 12 M cDNA (R2 = 0.9807) with a limit of detection (LOD) of 1 &times, 29 M. The DNA biosensor was reusable for three consecutive applications after regeneration with mild sodium hydroxide. The sandwich-type optical biosensor was well validated with a molecular reverse transcription polymerase chain reaction (RT-PCR) technique for screening of dengue virus in clinical samples, e.g., serum, urine, and saliva from dengue virus-infected patients under informed consent.

Biosensor optik berasaskan hemoglobin (Hb) terpegun pada mikrosfera poli(n-butil akrilat-co-N-akriloksisuksinimida) [poli(nBA-NAS)] telah dibangunkan bagi mengesan kepekatan ion nitrit (NO2-). Kompleks HEM ferum dalam Hb memangkinkan tindak balas penurunan ion NO2- kepada nitrik oksida (NO) lalu bergabung dengan deoksihemoglobin (HbFe2+) membentuk kompleks ferum-nitrosil-hemoglobin (HbFe2+-NO) yang berwarna hijau kekuningan. Spektrofotometer pantulan gentian optik digunakan untuk memantau kepekatan ion NO2- secara kuantitatif berdasarkan perubahan warna Hb terpegun pada mikrosfera poliakrilat daripada perang kemerahan ke hijau kekuningan pada panjang gelombang pantulan maksimum 668 nm. Pencirian terhadap biosensor nitrit reflektometrik melibatkan ujian kesan pH, kesan kepekatan Hb, julat rangsangan linear, kebolehasilan, jangka hayat dan kesan gangguan ion telah dijalankan. Biosensor ion NO2- optik terbangun memaparkan julat linear dinamik daripada 5 hingga 50 mg mL-1 (R2=0.9894) pada pH7.0 dengan had pengesanan (LOD) sebanyak 3.3 mg mL-1 dan nilai sisihan piawai relatif (RSD) kebolehasilan biosensor sebanyak 5.8%. Jangka hayat biosensor optik nitrit tersebut adalah selama 36 hari dan majoriti ion asing yang sering wujud bersama ion NO2- dalam sampel air semula jadi tidak menunjukkan kesan gangguan yang bererti terhadap penentuan ion NO2- menggunakan biosensor optik terbangun kecuali ion Hg2+, Ag+, Br- dan S2-.

Benzene, toluene, ethylbenzene and xylenes (BTEX) are well known hazardous volatile organic compounds (VOCs) due to their human health risks and photochemical effects. The main objective of this study was to estimate BTEX levels and evaluate interspecies ratios and ozone formation potentials (OFP) in the ambient air of urban Kuala Lumpur (KL) based on a passive sampling method with a Tenax® GR adsorbent tube. Analysis of BTEX was performed using a thermal desorption (TD)-gas chromatography mass spectrometer (GCMS). OFP was calculated based on the Maximum Incremental Reactivity (MIR). Results from this study showed that the average total BTEX during the sampling period was 66.06 ± 2.39 μg/m3. Toluene (27.70 ± 0.97 μg/m3) was the highest, followed by m,p-xylene (13.87 ± 0.36 μg/m3), o-xylene (11.49 ± 0.39 μg/m3), ethylbenzene (8.46 ± 0.34 μg/m3) and benzene (3.86 ± 0.31 μg/m3). The ratio of toluene to benzene (T:B) is > 7, suggesting that VOCs in the Kuala Lumpur urban environment are influenced by vehicle emissions and other anthropogenic sources. The average of ozone formation potential (OFP) value from BTEX was 278.42 ± 74.64 μg/m3 with toluene and xylenes being the major contributors to OFP. This study also indicated that the average of benzene concentration in KL was slightly lower than the European Union (EU)-recommended health limit value for benzene of 5 μg/m3 annual exposure.

Heavy metals are widely used in various industries and became a great concern all over the world due to environmental contamination. This study provides an assessment of seasonal variability and risks to human health associated with the exposure to heavy metals concentrated in Langat river water of Malaysia. The Department of Environment (DOE) Malaysia kindly provided the heavy metal concentration data in water for this study. Several multivariate estimation such as an independent t test, box-and-whisker plot and Principal component analysis were carried out to evaluate the seasonal variation of metals concentration in water. The average value of ten analyzed metals was 250.81 µg/l and followed in order of abundance by August > Jun > February > October > April > December > March > May > September > January > July > November. The calculated HPI was 123.42, which is far above the critical index value of 100, indicating pollution with respect to heavy metals. Estimates of health risks associated with river water were summarized according to non-carcinogenic and carcinogenic health effects. No potential threat was detected for noncarcinogenic risk as the HI values calculated were

Science education emphasises on obtaining knowledge, in which includes hands-on knowledge involving experiments conducted in laboratories. However, since experiments require interactions between students, substances, and equipment, laboratories that can pose great risks to users. In this regards, the Ministry of Education Malaysia has taken proactive approach to enhance laboratory safety via School Science Laboratory Management and Safety guidebook, textbooks, and science based practical workbooks that are used throughout secondary schools in Malaysia. It is challenging to ascertain students’ awareness on laboratory safety throughout Malaysia, hence this study selected 8 secondary schools located in Pahang as case study to determine students’ awareness on laboratory safety. A questionnaire was developed by focusing on five components, namely work procedure, safety equipment, handling experiments, chemical waste management, and emergency response plan, and then the questionnaire was completed by 558 science stream students from schools located at urban and rural areas. The results of this study indicate that the overall level of students’ awareness on laboratory safety is at medium-high level, and this has shown that the existing measures in secondary school to enhance awareness of laboratory safety is adequate. Nevertheless, there are still room for improvement to further enhance students’ awareness on laboratory safety in Malaysia. Keywords: Laboratory safety, awareness, secondary school, Malaysia Pendidikan sains memberi kepentingan kepada pemerolehan ilmu dan memberi penekanan khusus kepada kerja amali yang dijalankan di dalam makmal sains. Memandangkan kerja amali memerlukan interaksi antara pelajar dengan pelbagai bahan dan peralatan, ia menjadikan makmal sains berisiko kepada penggunanya. Sehubungan dengan itu, Kementerian Pendidikan Malaysia telah memperkukuhkan keselamatan makmal melalui garis panduan Pengurusan dan Keselamatan Makmal Sains, buku teks dan buku amali yang digunapakai di sekolah menengah. Ia adalah mencabar untuk menentukan tahap kesedaran keselamatan makmal di seluruh Malaysia, maka kajian ini telah memilih 8 sekolah menengah yang terletak di Pahang sebagai kajian kes. Soal selidik telah dibangunkan dengan memberi fokus kepada lima komponen utama keselamatan makmal sains, iaitu prosedur kerja, peralatan keselamatan, pengendalian eksperimen, pembuangan sisa bahan kimia dan pelan tindakan kecemasan, dan kemudian soal selidik ini telah dijawab oleh 558 pelajar sains dari sekolah bandar dan luar bandar. Hasil kajian menunjukkan bahawa tahap kesedaran keseluruhan untuk keselamatan makmal adalah pada tahap sederhanda-tinggi, dan ini telah menunjukkan kaedah sedia ada di sekolah menengah adalah memadai. Walaubagaimanapun, ia masih terdapat peluang untuk penambahbaikan serta memperkukuhkan tahap kesedaran pelajar terhadap keselamatan makmal di Malaysia. Kata kunci: Keselamatan makmal, kesedaran, sekolah menengah, Malaysia

Mass-spectrometry-based and X-ray fluorescence-based techniques have allowed the study of the distribution of Zn2+ ions at extracellular and intracellular levels over the past few years. However, there are some issues during purification steps, sample preparation, suitability for quantification, and the instruments’ availability. Therefore, work on fluorescent sensors based on 8-aminoquinoline as tools to detect Zn2+ ions in environmental and biological applications has been popular. Introducing various carboxamide groups into an 8-aminoquinoline molecule to create 8-amidoquinoline derivatives to improve water solubility and cell membrane permeability is also a recent trend. This review aims to present a general overview of the fluorophore 8-aminoquinoline and its derivatives as Zn2+ receptors for zinc sensor probes. Various fluorescent chemosensor designs based on 8-amidoquinoline and their effectiveness and potential as a recognition probe for zinc analysis were discussed. Based on this review, it can be concluded that derivatives of 8-amidoquinoline have vast potential as functional receptors for zinc ions primarily because of their fast reactivity, good selectivity, and bio-compatibility, especially for biological applications. To better understand the Zn2+ ion fluorophores’ function, diversity of the coordination complex and geometries need further studies. This review provides information in elucidating, designing, and exploring new 8-amidoquinoline derivatives for future studies for the improvement of chemosensors that are selective and sensitive to Zn2+.

An optical aptasensor-based sensing platform for rapid insulin detection was fabricated. Aminated porous silica microparticles (PSiMPs) were synthesized via a facile mini-emulsion method to provide large surface area for covalent immobilization of insulin-binding DNA aptamer (IGA3) by glutaraldehyde cross-linking protocol. A Nickel-salphen type complex with piperidine side chain [Ni(II)-SP] was synthesized with a simple one-pot reaction, and functionalized as an optical label due to strong π-π interaction between aromatic carbons of G-quadruplex DNA aptamer and planar aromatic groups of Ni(II)-SP to form the immobilized IGA3-Ni(II)-SP complex, i.e. the dye-labeled aptamer, thereby bringing yellow colouration to the immobilized G-quartet plane. Optical characterization of aptasensor towards insulin binding was carried out with a fiber optic reflectance spectrophotometer. The maximum reflectance intensity of the immobilized IGA3-Ni(II)-SP complex at 656 nm decreased upon binding with insulin as aptasensor changed to brownish orange colouration in the background. This allows optical detection of insulin as the colour change of aptasensor is dependent on the insulin concentration. The linear detection range of the aptasensor is obtained from 10 to 50 μIU mL−1 (R2 = 0.9757), which conformed to the normal fasting insulin levels in human with a limit of detection (LOD) at 3.71 μIU mL−1. The aptasensor showed fast response time of 40 min and long shelf life stability of >3 weeks. Insulin detection using healthy human serums with informed consent provided by participants suggests the DNA aptamer biosensor was in good agreement with ELISA standard method using BIOMATIK Human INS (Insulin) ELISA Kit.

Lack of treated water system in Sabah has increase human dependency to groundwater sources. The presence of contaminants such as nitrate in groundwater can pose severe health implications to human, such as methemoglobinemia and cancerous diseases. The objectives of this paper were to quantify the nitrate concentration in groundwater, to calculate potential human health risk exposure of nitrate in groundwater and to compare the potential human health risk exposure of nitrate between rural and agriculture areas. Six tube wells were selected at Inanam and Kota Belud district and involved one-hundred eighty respondents aged from 7 to 12 years old. The groundwater samples were analyzed using Cadmium Reduction method of HACH DR2800 Spectrophotometer and human health risk exposure were assessed using Chronic Daily Intake (CDI) and Hazard Index (HI) after set of information of respondents were obtained by questionnaires. Result obtained were showing mean ± S.D of nitrate levels in groundwater well and filtered water of agriculture (0.79 ± 0.33 mg/L; 0.33 ± 0.29 mg/L) and rural (0.50 ± 0.12mg/L; 0.53 ± 0.10 mg/L) areas were within the acceptable value limit set by National Drinking Water Quality Standard of Malaysia (10 mg/L). The statistical analysis of Kruskal-Wallis and one-way ANOVA test implied there were no significant differences of nitrate levels between two areas (p>0.05). Moreover, the mean ± S.D of CDI for agriculture and rural areas were 0.0064 ± 0.0056 mg/kg/day 0.0140 ± 0.0096 mg/kg/day respectively and HI were less than 1. The insignificant differences of potential human health risk were noted in terms of gender and age of respondents between two areas. This specified that the human health risk of respondents involved in this study was in acceptable range and not exposed to severe health risks.