Environmental risk assessment of diclofenac residues in surface waters and wastewater: a hidden global threat to aquatic ecosystem.

Pharmaceuticals are chemical compounds employed as medicinal drugs. They have severe physic-chemical properties which make them destructive for non-target species. Consequently, their continuous addition in the environment may pose hazardous effects. Among these, diclofenac (DCF), a non-steroidal anti-inflammatory drug (NSAID), is extensively used in Pakistan which may lead to its accumulation in both terrestrial and aquatic environment. Present study aims to assess the presence and concentration of pharmaceutically active drug (DCF) in surface water and wastewater of twin cities of Pakistan (Rawalpindi and Islamabad). For this purpose, a validated high-performance liquid chromatography (HPLC) method was adopted involving solid-phase extraction procedure. Wastewater samples were collected from various sites of Rawalpindi and Islamabad. Results of HPLC analysis revealed that DCF was extant with considerably high concentration, not only in wastewater but also in surface water samples. Concentrations as high as 216 µg L-1 was detected in Rawat industrial area and low as 8 µg L-1 was detected in dairy farm wastewater samples collected from Taramri. However, maximum DCF levels in residential wastewater and hospital wastewater were detected to be 105 µg L-1 and 34 µg L-1, respectively. Moreover, the highest detected level (116 µg L-1) was found in surface water of Sawan River. Further, results of ecological risk assessment revealed its possible toxic effects of DCF on various aquatic organisms.

Occurrence, influencing factors, toxicity, regulations, and abatement approaches for disinfection by-products in chlorinated drinking water: A comprehensive review.

Disinfection is considered as a vital step to ensure the supply of clean and safe drinking water. Various approaches are adopted for this purpose; however, chlorination is highly preferred all over the world. This method is opted owing to its several advantages. However, it leads to the formation of certain by-products. These chlorination disinfection by-products (DBPs) are genotoxic, carcinogenic and mutagenic. Still chlorination is being practiced worldwide. Present review gives insights into the occurrence, toxicity and factors affecting the formation of regulated (THMs, HAAs) and emerging DBPs (N-DBPs, HKs, HAs and aromatic DBPs) found in drinking water. Furthermore, remediation techniques used to control DBPs have also been summarized here. Key findings are: (i) concentration of regulated DBPs surpassed the permissible limit in most of the regions, (ii) high chlorine dose, high NOM, more reaction time (up to 3 h) and high temperature (up to 30 °C) enhance the formation of THMs and HAAs, (iii) high pH favors the formation of THMs while low pH is suitable of the formation of HAAs, (iv) high NOM, low temperature, low chlorine dose and moderate pH favors the formation of unstable DBPs (N-DBPs, HKs and HAs), (v) DBPs are toxic not only for humans but for aquatic fauna as well, (vi) membrane technologies, enhanced coagulation and AOPs remove NOM, (vii) adsorption, air stripping and other physical and chemical methods are post-formation approaches (viii) step-wise chlorination is assumed to be an efficient method to reduce DBPs formation without any treatment. Toxicity data revealed that N-DBPs are found to be more toxic than C-DBPs and aromatic DBPs than aliphatic DBPs. In majority of the studies, merely THMs and HAAs have been studied and USEPA has regulated just these two groups. Future studies should focus on emerging DBPs and provide information regarding their regulation.

Health risk assessment of radioactive footprints of the urban soils in the residents of Dera Ghazi Khan, Pakistan.

The aim of the study was to evaluate the radiation levels, radiological doses and excess lifetime cancer risk possessed by the urban soils that were collected from the vicinity of the exclusive mining and excavation centers of Dera Ghazi Khan. The high purity germanium detector was utilized for assessment of naturally occurring radionuclides (NORMs) in soil and results showed that the average activity concentrations of 226Ra, 232Th, and 40K (37 Bq/kg, 43.07 Bq/kg, 737 Bq/kg respectively) surpassed the world's average documented values (35 Bq/kg, 30 Bq/kg, and 400 Bq/kg respectively). Moreover, the average values of radiological hazards assessment like radium equivalent, internal and external hazard indices, absorbed dose rate, annual gonadal dose equivalent and excess lifetime cancer risk were 155.70 (Bq/kg), 0.4, 0.5, 73.96 (nGy/h) 90.73 (µSv/y), 476.24 (µSv/y) and 0.31(10-3) respectively. The data acquired was analyzed using descriptive statistics, cluster analysis and principal component analysis. ArcGIS (10.5) software was utilized for developing maps of radionuclide's concentration for the study area. Results of the study may serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.

Comparative efficacy of mitigation techniques for the detoxification of Prunus persica (L.) from selected pesticide residues.

Fruits are the valuable and important components of human diet. Among them, Prunus persica is a rich source of different minerals and dietary fibers. In Pakistan, the total annual production of P. persica is approximately 837,000 tons. In order to enhance agricultural yield and quality, the plant protection agents are employed during fruit production. Ultimately, this in turn leads to the incorporation of pesticide residues in fruits. In present study, an effort has been made for the determination of three selected pesticide residues, i.e., chlorpyrifos (CPF), difenoconazole (DFN), and carbendazim (CRB) in samples of P. persica collected from Swat territory. Samples were analyzed through high performance liquid chromatography (HPLC). Results revealed the occurrence of all three pesticides in studied samples; however, levels of CPF and DFN were found to be higher than MRLs. Moreover, the effects of different mitigation techniques revealed that highest reduction of CPF, DFN, and CRB (86%, 97%, 89%) residues was obtained by treatment with 10% CH3COOH followed by 10% NaCl (74%, 78%, 84%). The lowest reduction was obtained by treatment with 10% solution of NaOH (52%, 55%, 63%).

Dechlorane Plus as an emerging environmental pollutant in Asia: a review.

Dechlorane Plus (DP) is an unregulated, highly chlorinated flame retardant. It has been manufactured from past 40 years but its presence in the environment was initially reported in 2006. Later, it has been found in various biotic and abiotic environmental matrices. However, little attention has been paid to monitor its presence in Asia. Many studies have reported the occurrence of DP in the environment of Asia, yet the data are scarce, and studies are limited to few regions. The objective of present review is to summarize the occurrence, distribution, and toxicity of this ubiquitous pollutant in various environmental matrices (biotic and abiotic). DP has also been reported in the areas with no emission sources, which proves its long-range transport. Moreover, urbanization and industrialization also affect the distribution of DP, i.e., high levels of DP have been found in urban areas relative to the rural. Tidal movement also incorporates in transport of DP across the aquatic system. Further, bioaccumulation trend of DP in various tissues is kidney > liver > muscle tissues, whereas, blood brain barrier resists its accumulation in brain tissues. Additionally, gender-based accumulation trends revealed high DP levels in females in comparison to males due to strong metabolism of males. Furthermore, methodological aspects and instrumental analysis used in previous studies have also been summarized here. However, data on biomagnification in aquatic ecosystem and bioaccumulation of DP in terrestrial food web are still scarce. Toxicity behavior of syn-DP and anti-DP is still unknown which might gain the interest for future studies.