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Baseline distribution and sources of linear alkyl benzenes (LABs) in surface sediments from Brunei Bay, Brunei

Alkhadher SAA, Zakaria MP, Yusoff FM, Kannan N, Suratman S, Keshavarzifard M, et al.

Mar Pollut Bull, 2015 Dec 15;101(1):397-403.
PMID: 26478457 DOI: 10.1016/j.marpolbul.2015.10.011

Sewage pollution is one of major concerns of coastal and shoreline settlements in Southeast Asia, especially Brunei. The distribution and sources of LABs as sewage molecular markers were evaluated in surface sediments collected from Brunei Bay. The samples were extracted, fractionated and analyzed using gas chromatography- mass spectrometry (GC-MS). LABs concentrations ranged from 7.1 to 41.3 ng g(-1) dry weight (dw) in surficial sediments from Brunei Bay. The study results showed LABs concentrations variably due to the LABs intensity and anthropogenic influence along Brunei Bay in recent years. The ratio of Internal to External isomers (I/E ratio) of LABs in sediment samples from Brunei Bay ranged from 0.56 to 2.17 along Brunei Bay stations, indicating that the study areas were receiving primary and secondary effluents. This is the first study carried out to assess the distribution and sources of LABs in surface sediments from Brunei Bay, Brunei.
Forensic investigation of aliphatic hydrocarbons in the sediments from selected mangrove ecosystems in the west coast of Peninsular Malaysia

Vaezzadeh V, Zakaria MP, Shau-Hwai AT, Ibrahim ZZ, Mustafa S, Abootalebi-Jahromi F, et al.

Mar Pollut Bull, 2015 Nov 15;100(1):311-320.
PMID: 26323864 DOI: 10.1016/j.marpolbul.2015.08.034

Peninsular Malaysia has gone through fast development during recent decades resulting in the release of large amounts of petroleum and its products into the environment. Aliphatic hydrocarbons are one of the major components of petroleum. Surface sediment samples were collected from five rivers along the west coast of Peninsular Malaysia and analyzed for aliphatic hydrocarbons. The total concentrations of C10 to C36 n-alkanes ranged from 27,945 to 254,463ng·g(-1)dry weight (dw). Evaluation of various n-alkane indices such as carbon preference index (CPI; 0.35 to 3.10) and average chain length (ACL; 26.74 to 29.23) of C25 to C33 n-alkanes indicated a predominance of petrogenic source n-alkanes in the lower parts of the Rivers, while biogenic origin n-alkanes from vascular plants are more predominant in the upper parts, especially in less polluted areas. Petrogenic sources of n-alkanes are predominantly heavy and degraded oil versus fresh oil inputs.
Linear alkylbenzenes in surface sediments of an estuarine and marine environment in peninsular Malaysia

Alkhadher SAA, Kadir AA, Zakaria MP, Al-Gheethi A, Keshavarzifard M, Masood N, et al.

Mar Pollut Bull, 2020 Apr;153:111013.
PMID: 32275559 DOI: 10.1016/j.marpolbul.2020.111013

Linear alkylbenzenes were determined in the surface sediments of Muar River and Pulau Merambong, Peninsular Malaysia. The concentrations ranged from 87.4 ng g-1 to 188.1 ng g-1 and from 67.4 ng g-1 to 98.2 ng g-1 of dry weight, respectively. The composition profiles of LABs were characterized, and sewage treatment levels were identified. The ratios of internal to external isomers (I/E ratios) of the linear alkylbenzenes in Muar River sediments ranged from 1.7 to 2.2, whereas those of Pulau Merambong sediments ranged from 1.6 to 1.7. The calculated LAB ratios indicated that the study areas received primary and secondary sewage effluents. The degradation of linear alkylbenzenes in Muar River ranged from 33% to 43%, and that in Pulau Merambong ranged from 33% to 34%. The higher degradation indices in Muar River are a sign of improvement in wastewater treatment.
Monitoring of linear alkyl benzenes (LABs) in riverine and estuarine sediments in Malaysia

Masood N, Alkhadher SAA, Magam SM, Halimoon N, Alsukaibi A, Zakaria MP, et al.

Environ Geochem Health, 2021 Oct 25.
PMID: 34697724 DOI: 10.1007/s10653-021-01088-6

The aim of this a pioneering research is to investigate linear alkylbenzenes (LABs) as biomarkers of sewage pollution in sediments collected from four rivers and estuaries of the south and east of Peninsular Malaysia. The sediment samples went through soxhlet extraction, two-step column chromatography purification, fractionation and gas chromatography-mass spectrometry (GC-MS) analysis. Principal component analysis (PCA) with multivariate linear regression (MLR) was used as well for source apportionment of LABs. The results of this study showed that total LAB concentration was 36-1196 ng g-1dw. The internal to external isomer ratios (I/E ratio) of LABs were from 0.56 to 3.12 indicated release of raw sewage and primary and secondary effluents into the environment of south and east of Peninsular Malaysia. Our research supported that continuous monitoring of sewage pollution to limit the environmental pollution in riverine and estuarine ecosystem.
Seasonal variations in the distribution of aliphatic hydrocarbons in surface sediments from the Selangor River, Peninsular Malaysia's West Coast

Magam SM, Masood N, Alkhadher SAA, Alanazi TYA, Zakaria MP, Sidek LM, et al.

Environ Geochem Health, 2024 Jan 16;46(2):38.
PMID: 38227164 DOI: 10.1007/s10653-023-01828-w

The seasonal variation of petroleum pollution including n-alkanes in surface sediments of the Selangor River in Malaysia during all four climatic seasons was investigated using GC-MS. The concentrations of n-alkanes in the sediment samples did not significantly correlate with TOC (r = 0.34, p > 0.05). The concentrations of the 29 n-alkanes in the Selangor River ranged from 967 to 3711 µg g-1 dw, with higher concentrations detected during the dry season. The overall mean per cent of grain-sized particles in the Selangor River was 85.9 ± 2.85% sand, 13.5 ± 2.8% clay, and 0.59 ± 0.34% gravel, respectively. n-alkanes are derived from a variety of sources, including fresh oil, terrestrial plants, and heavy/degraded oil in estuaries. The results of this study highlight concerns and serve as a warning that hydrocarbon contamination is affecting human health. As a result, constant monitoring and assessment of aliphatic hydrocarbons in coastal and riverine environments are needed.
Anthropogenic waste indicators (AWIs), particularly PAHs and LABs, in Malaysian sediments: Application of aquatic environment for identifying anthropogenic pollution

Masood N, Zakaria MP, Halimoon N, Aris AZ, Magam SM, Kannan N, et al.

Mar Pollut Bull, 2016 Jan 15;102(1):160-75.
PMID: 26616745 DOI: 10.1016/j.marpolbul.2015.11.032

Polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes (LABs) were used as anthropogenic markers of organic chemical pollution of sediments in the Selangor River, Peninsular Malaysia. This study was conducted on sediment samples from the beginning of the estuary to the upstream river during dry and rainy seasons. The concentrations of ƩPAHs and ƩLABs ranged from 203 to 964 and from 23 to 113 ng g(-1) dry weight (dw), respectively. In particular, the Selangor River was found to have higher sedimentary levels of PAHs and LABs during the wet season than in the dry season, which was primarily associated with the intensity of domestic wastewater discharge and high amounts of urban runoff washing the pollutants from the surrounding area. The concentrations of the toxic contaminants were determined according to the Sediment Quality Guidelines (SQGs). The PAH levels in the Selangor River did not exceed the SQGs, for example, the effects range low (ERL) value, indicating that they cannot exert adverse biological effects.
Baseline distributions and sources of Polycyclic Aromatic Hydrocarbons (PAHs) in the surface sediments from the Prai and Malacca Rivers, Peninsular Malaysia

Keshavarzifard M, Zakaria MP, Hwai TS, Yusuff FF, Mustafa S, Vaezzadeh V, et al.

Mar Pollut Bull, 2014 Nov 15;88(1-2):366-72.
PMID: 25173594 DOI: 10.1016/j.marpolbul.2014.08.014

In this study, the surface sediments of the Malacca and Prai Rivers were analyzed to identify the distributions, and sources of Polycyclic Aromatic Hydrocarbons (PAHs). The total PAH concentrations varied from 716 to 1210 and 1102 to 7938 ng g(-1)dw in the sediments of the Malacca and Prai Rivers, respectively. The PAH concentrations can be classified as moderate and high level of pollution in the sediments of the Malacca and Prai Rivers, respectively. The comparison of PAHs with the Sediment Quality Guidelines (SQGs) indicates that the PAHs in the sediments of the Malacca and Prai Rivers may have the potential to cause adverse toxicity effects on the sampled ecosystems. The diagnostic ratios of individual PAHs indicate both petrogenic- and pyrogenic-origin PAHs with dominance of pyrogenic source in both rivers. These findings demonstrate that the environmental regulations in Malaysia have effectively reduced the input of petrogenic petroleum hydrocarbons into rivers.
Seasonal variability of anthropogenic indices of PAHs in sediment from the Kuala Selangor River, west coast Peninsular Malaysia

Masood N, Halimoon N, Aris AZ, Zakaria MP, Vaezzadeh V, Magam SM, et al.

Environ Geochem Health, 2018 Dec;40(6):2551-2572.
PMID: 29802607 DOI: 10.1007/s10653-018-0122-z

Rapid increase in industrialization and urbanization in the west coast of Peninsular Malaysia has led to the intense release of petroleum and products of petroleum into the environment. Surface sediment samples were collected from the Selangor River in the west coast of Peninsular Malaysia during four climatic seasons and analyzed for PAHs and biomarkers (hopanes). Sediments were soxhlet extracted and further purified and fractionated through first and second step column chromatography. A gas chromatography-mass spectrometry (GC-MS) was used for analysis of PAHs and hopanes fractions. The average concentrations of total PAHs ranged from 219.7 to 672.3 ng g-1 dw. The highest concentrations of PAHs were detected at 964.7 ng g-1 dw in station S5 in the mouth of the Selangor River during the wet inter-monsoonal season. Both pyrogenic and petrogenic PAHs were detected in the sediments with a predominance of the former. The composition of hopanes was homogeneous showing that petroleum hydrocarbons share an identical source in the study area. Diagnostic ratios of hopanes indicated that some of the sediment samples carry the crankcase oil signature.
Evaluation of distribution and sources of sewage molecular marker (LABs) in selected rivers and estuaries of Peninsular Malaysia

Magam SM, Zakaria MP, Halimoon N, Aris AZ, Kannan N, Masood N, et al.

Environ Sci Pollut Res Int, 2016 Mar;23(6):5693-704.
PMID: 26581689 DOI: 10.1007/s11356-015-5804-9

This is the first extensive report on linear alkylbenzenes (LABs) as sewage molecular markers in surface sediments collected from the Perlis, Kedah, Merbok, Prai, and Perak Rivers and Estuaries in the west of Peninsular Malaysia. Sediment samples were extracted, fractionated, and analyzed using gas chromatography mass spectrometry (GC-MS). The concentrations of total LABs ranged from 68 to 154 (Perlis River), 103 to 314 (Kedah River), 242 to 1062 (Merbok River), 1985 to 2910 (Prai River), and 217 to 329 ng g(-1) (Perak River) dry weight (dw). The highest levels of LABs were found at PI3 (Prai Estuary) due to the rapid industrialization and population growth in this region, while the lowest concentrations of LABs were found at PS1 (upstream of Perlis River). The LABs ratio of internal to external isomers (I/E) in this study ranged from 0.56 at KH1 (upstream of Kedah River) to 1.35 at MK3 (Merbok Estuary) indicating that the rivers receive raw sewage and primary treatment effluents in the study area. In general, the results of this paper highlighted the necessity of continuation of water treatment system improvement in Malaysia.
Fulltext Efficacy, Tolerability, and Biomarker Analyses of Once-Every-2-Weeks Cetuximab Plus First-Line FOLFOX or FOLFIRI in Patients With KRAS or All RAS Wild-Type Metastatic Colorectal Cancer: The Phase 2 APEC Study

Cheng AL, Cornelio G, Shen L, Price T, Yang TS, Chung IJ, et al.

Clin Colorectal Cancer, 2017 06;16(2):e73-e88.
PMID: 27780749 DOI: 10.1016/j.clcc.2016.08.005

BACKGROUND: In patients with KRAS wild-type (wt) metastatic colorectal cancer (mCRC), outcomes with first-line chemotherapies are improved by adding weekly cetuximab. The APEC study investigated first-line once-every-2-weeks cetuximab plus chemotherapy for patients with KRAS wt mCRC; additional biomarker subgroups were also analyzed.
PATIENTS AND METHODS: APEC was a nonrandomized phase 2 trial conducted in the Asia-Pacific region. Patients (n = 289) received once-every-2-weeks cetuximab with investigator's choice of chemotherapy (FOLFOX or FOLFIRI). The primary end point was best confirmed overall response rate (BORR); progression-free survival (PFS) and overall survival (OS) were secondary end points. Early tumor shrinkage (ETS) and depth of response (DpR) were also evaluated.
RESULTS: In the KRAS wt population, BORR was 58.8%, median PFS 11.1 months, and median OS 26.8 months. Expanded RAS mutational analysis revealed that patients with RAS wt mCRC had better outcomes (BORR = 64.7%; median PFS = 13.0 months; median OS = 28.4 months). The data suggest that ETS and DpR may be associated with survival outcomes in the RAS wt population. Although this study was not designed to formally assess differences in outcome between treatment subgroups, efficacy results appeared similar for patients treated with FOLFOX and FOLFIRI. There were no new safety findings; in particular, grade 3/4 skin reactions were within clinical expectations.
CONCLUSION: The observed activity and safety profile is similar to that reported in prior first-line pivotal studies involving weekly cetuximab, suggesting once-every-2-weeks cetuximab is effective and tolerable as first-line therapy and may represent an alternative to weekly administration.