Niza Samsuddin

Pesticide Exposure and Cardiovascular Hemodynamic Parameters Among Male Workers Involved in Mosquito Control in East Coast of Malaysia

BACKGROUND Research findings have linked exposure to pesticides to an increased risk of cardiovascular (CVS) diseases. Therefore, this study aimed to assess the impact of chronic mix-pesticides exposure on CVS hemodynamic parameters. METHODS A total of 198 male Malay pesticide-exposed and 195 male Malay nonexposed workers were examined. Data were collected through exposure-matrix assessment, questionnaire, blood analyses, and CVS assessment. Explanatory variables comprised of lipid profiles, paraoxonase 1 (PON1), and oxidized low-density lipoprotein (ox-LDL). Outcome measures comprised of brachial and aortic diastolic blood pressure (DBP) and systolic BP (SBP), heart rate, and pulse wave velocity (PWV). Linear regressions identified the B coefficient showing how many units of CVS parameters are associated with each unit of covariates. RESULTS Diazoxonase was significantly lower and ox-LDL was higher among pesticide-exposed workers than the comparison group. The final multivariate linear regression model revealed that age, body mass index (BMI), smoking, and pesticide exposure were independent predictors of brachial and aortic DBP and SBP. Pesticide exposure was also associated with heart rate, but not with PWV. Lipid profiles, PON1 enzymes, and ox-LDL showed no association with any of the CVS parameters. CONCLUSIONS Chronic mix-pesticide exposure among workers involved in mosquito control has possible association with depression of diazoxonase and the increase in ox-LDL, brachial and aortic DBP and SBP, and heart rate. This study raises concerns that those using pesticides may be exposed to hitherto unrecognized CVS risks among others. If this is confirmed by further studies, greater efforts will be needed to protect these workers.

Ventilation Performance Assessment of an Educational Building in a Hot and Humid Climate

Air Handling Units in mechanical ventilation system possess a high degree of potential to circulate contaminants within occupied spaces of a building which often results in sick building syndrome (SBS), building related illness (BRI) and other indoor air quality (IAQ) related issues. This happens despite the expected role of ventilation systems to create a balance of thermal comfort and indoor air quality to the building occupants as well as the stored components. In the hot and humid climate mechanical ventilation systems play an important role of controlling the indoor hygrothermal conditions. Inadequate performance of the mechanical ventilation systems result in several issues ranging from human occupants discomfort, mechanical damages to archival materials and mould problem amongst others. This study presents the measurement and analysis of the mechanical ventilation systems’ performance and its effect on various indoor spaces in an academic building in Malaysia. Measurement of airflow, thermal and hygric conditions of the facility together with the aero-biological sampling were executed. The ventilation performance assessment revealed that the AHU fails in its cooling and dehumidification capacities as most of the occupied zones witnessed elevated humidity and low temperature and hence poor hygrothermal performance. On the other hand, results of bio-aerosol assessment indicates that the AHU performs well in its decontamination capacities by reducing the microbial level between the AHU and the occupied zones. The dominant species of mould in the assessed spaces are Penicillium sp., Yeast, Cladosporium sp., and Chaetomium sp. with 100 % occurrence in all the assessed space. On the other hand, Black Mold, Syntalidium sp., and zygomycetes are the least species in spaces with 25 % occurrence. The presence of black mould portends a great danger to the occupants’ health and therefore requires urgent attention.

Peat soils stabilization using Effective Microorganisms (EM)

Peat soil is known as geotechnical problematic soil since it is the softest soil having highly organic and moisture content which led to high compressibility, low shear strength and long-term settlement. The aim of this study was to obtain the stabilized peat soils using the Effective Microorganisms (EM). The volume of EM added and mixed with peat soils varied with 2%, 4%, 6%, 8% and 10% and then were cured for 7, 14 and 21 days. The experiment was done for uncontrolled and controlled moisture content. Prior conducting the main experiments, the physical properties such as moisture content, liquid limit, specific gravity, and plastic limit etc. were measure for raw peat samples. The Unconfined Compressive Strength (UCS) test was performed followed by regression analysis to check the effect of EM on the soil strength. Obtained results have shown that the mix design for controlled moisture contents showed the promising improvement in their compressive strength. The peat soil samples with 10% of EM shows the highest increment in UCS value and the percentage of increments are in the range of 44% to 65% after curing for 21 days. The regression analysis of the EM with the soil compressive strength showed that in controlled moisture conditions, EM significantly improved the soil stability as the value of R2 ranged between 0.97 – 0.78. The results have indicated that the addition of EM in peat soils provides significant improving in the strength of the soil as well as the other engineering properties.

Organic Arsenical Exposure Stimulates Atherosclerosis Through Oxidative Stress Increase and Adhesion Molecule Expression

Approximately 100 million people are exposed to arsenic worldwide, majorly through drinking water and anthropogenic activities. Monosodium methylarsonate (MSMA) is a potent organoarsenical content of herbicides used in many Asian countries. Epidemiological studies have linked inorganic arsenic exposure with atherosclerosis, whereas organoarsenicals toxicological studies are scanty. Paraoxonase 1 (PON1) enzyme suppresses systemic Ox-LDL generation, thereby preventing atherosclerosis. We investigated effects of MSMA oral exposure on PON1, lipid peroxidation and atherosclerosis development. Five groups (n=11) of Sprague- Dawley rats received daily intubation of MSMA at 0 (control), 42.1, 63.2, 126.4 and 210.7 mg/kg BW respectively for 16 weeks. Serum samples were analysed for PON1 activities, Ox-LDL and MDA levels. Histomorphometric evaluation (H&E and VVG) and immunohistochemistry (VCAM-1 and ICAM-1) were done on aorta. High mortality rate led to discontinuation of 126.4 and 210.7 mg/kg BW treatment groups. Groups treated with 42.1 and 63.2 mg/kg B.W. MSMA had a significantly higher MDA (p=0.004,CI: 2.73-0.82) and Ox-LDL (p<0.0001,CI: 2425.07-955.45) levels but lower PON1:Ox-LDLratio (p<0.0001,CI: 0.49-1.07) compared to control. Microscopically, treatment groups showed early atherosclerotic intima thickening and positive VCAM-1 and ICAM-1 expressions. In conclusion, chronic MSMA exposure reduced PON1 ability to hydrolyse Ox-LDL and also induced inflammation by elevating oxidative stress that supports early atherosclerosis development.

Influence of Indoor Microclimate Distribution on Mould Infestation in a University Library

Indoor mould contamination portends grave consequence to the stored components as well as inhabitants of infested dwellings. Such defilement, which is due to favourable growth environment for micro-organisms, is often associated with Sick Building Syndrome (SBS) and other Building Related Illness (BRI). As the economic development of Malaysia continues, increase numbers of air-tight, fully air conditioned buildings are evolving. Currently limited guidelines exists on Indoor Air Quality (IAQ) in Malaysia and its knowledge amongst the public is lacking. Hence, diagnosing the aggravating factors favouring indoor mould becomes beneficial as earlier detection is often difficult until growth has advanced. The study aimed at investigating mould infestation in a mechanically ventilated library building in Malaysia. Microclimate parameter and mould sampling were carried out. The microbial investigation results in 72 isolates whose distribution were 86 % mould, 13 % yeast and 1 % bacterial. It is found that Aspegillus sp. and Onychocola sp. were most common. The library internal microclimate distribution is characterised by uneven hygrothermal profile which results in high level of cellulolytic mould species that are highly detrimental to books and other archival materials. It is recommended that the HVAC system operations and set-points be critiqued to bring the ambient to the preservation requirements. In addition, load balancing for thermal and hygric distribution analysis should be executed to eliminate dead-spots in temperature and moisture distributions.