The demand for bottled drinking water in Bangladesh is becoming popular due to the lack of safe drinking water sources. The present study was carried out to assess the water quality and public health impacts of local brands of bottled drinking water and tube-well water, compared to the imported ones. Several state-of-the-art techniques were employed to determine the contents of pH, EC, salinity, chloride, nitrates, nitrites, fluoride, sulfates, phosphates, bicarbonate, turbidity, color, total hardness, and total dissolved solids in the studied water samples. The measured data show that the level of dissolved minerals in the local branded bottled water is very low (with an exception for sample codes D1 and D8), while imported brands, Zamzam water, and tube-well water contain satisfactory level of minerals and fulfill Dietary Reference Intake requirements. Total coliform, fecal coliform, and E. coli were found to be absent in local brands of bottled water and tube-well water. On the other hand, concentrations of some radionuclides ⁴⁰K, ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²¹⁰Po, ²²²Rn, ¹³⁷Cs, and ²³²Th in local bottled water and tube-well water were found to be less than the permissible level given by WHO (2011). The results reveal that local bottled drinking water manufacturing companies may not be following standard guidelines and quality control steps properly. Thus, improvement in their standard operating process is urgently needed to ensure strict compliance with guidelines set by Bangladesh standards and testing institutions.

Concentration, source, ecological and health risks of sixteen polycyclic aromatic hydrocarbons (PAHs) were estimated for water and sediment samples of two urban rivers namely Buriganga River (BR) and Dhaleswari River (DR). The mean concentration of ∑PAHs in BR water and sediment were 9619.2 ngL⁻¹ and 351.6 ngg⁻¹, respectively. Furthermore, the average PAH concentrations detected in DR water and sediment were 1979.1 ngL⁻¹ and 792.9 ngg⁻¹, respectively. The composition profile showed that 3-ring PAHs were dominant in the water matrix; however, 5-ring PAHs were prevalent in the sediment samples of both rivers. Sources apportion study of PAHs indicated that mixed combustion and petroleum sources are responsible for PAHs contamination in the rivers. Ecological risk study of water suggested that the aquatic lives of both rivers are threatened by Fla, BbF, BkF, DahA, and IcdP, as presented above the threshold level. Comparison with sediment quality guidelines (SQGs) indicated that adverse effects might cause occasionally in the sediment ecosystem in DR at certain sampling sites for Nap, Acy, Fl, Phe, Ant, Pyr, Chr, BaP, and DahA. On the other hand, the presence of Nap, Acy and DahA might occasionally cause adverse biological effects in the BR sediment ecosystem. Estimated hazard quotient (HI > 1) and carcinogenic risk (CR_total > 10⁻⁴) values indicated that local inhabitants living in the vicinity of the rivers are prone to high health risks.

An oil-degrading bacteria, Bacillus velezensis S2, was found to produce rhamnolipid-like biosurfactant which showed significant emulsification and foaming activity while reducing the surface tension remarkably. This offers more ecological sustainability than the toxic chemical surfactants.

As far as comorbidity is concerned, cardiovascular diseases (CVD) appear to be accounted for the highest prevalence, severity, and fatality among COVID 19 patients. A wide array of causal links connecting CVD and COVID-19 baffle the overall prognosis as well as the efficacy of the given therapeutic interventions. At the centre of this puzzle lies ACE2 that works as a receptor for the SARS-CoV-2, and functional expression of which is also needed to minimize vasoconstriction otherwise would lead to high blood pressure. Furthermore, SARS-CoV-2 infection seems to reduce the functional expression of ACE2. Given these circumstances, it might be advisable to consider a treatment plan for COVID-19 patients with CVD in an approach that would neither aggravate the vasodeleterious arm of the renin-angiotensinogen-aldosterone system (RAAS) nor compromise the vasoprotective arm of RAAS but is effective to minimize or if possible, inhibit the viral replication. Given the immune modulatory role of Zn in both CVD and COVID-19 pathogenesis, zinc supplement to the selective treatment plan for CVD and COVID-19 comorbid conditions, to be decided by the clinicians depending on the cardiovascular conditions of the patients, might greatly improve the therapeutic outcome. Notably, ACE2 is a zinc metalloenzyme and zinc is also known to inhibit viral replication.