Environmental fate of imazapyr and imazapic herbicides in paddy soil and water and its potential health risk via anabas testudineus consumption / Siti Norashikin Mohamad Shaifuddin

Mixtures of imazapyr and imazapic herbicides are used to control weedy rice problem in Malaysian rice cultivation area. These two herbicides share the same characteristics which are high mobility, phyto-toxicity and persistency in soil, thus could pose problems to the environment and human health. Since there is limited information regarding the concentration and behaviour of imazapyr and imazapic herbicides in Malaysian paddy soil and water, this study was conducted: (i) to develop and optimize the extraction and detection method of imazapyr and imazapic in water, soil and fish tissue samples using HPLC-UV; (ii) to determine the concentration and distribution pattern of these herbicides for 120 days in paddy soil and water, and estimate their leaching potential capacity using GUS index; (iii) to evaluate their adsorption and desorption capability in soils; (iv) to evaluate their abiotic degradation in water and soil; and (v) to examine their level in Anabas testudineus, and estimate their potential health risk amongst farmers. Several extraction techniques including SPE, SLE and LLE were tested to extract imazapyr and imazapic in spiked water, soil and fish tissue samples. The extracts were then quantified using the optimized HPLC-UV. Collections of samples were carried out at Sawah Sempadan, Tanjung Karang, Selangor. Surface water and soil were sampled for 120 days, whereas A. testudineus were sampled just after rice harvesting period together with public survey. Adsorption-desorption and abiotic degradation of imazapyr and imazapic were investigated under controlled laboratory conditions using the standard protocols by USEPA. Results showed that SPE technique was able to successfully extract imazapyr and imazapic from spiked water and fish tissue, whereas SLE technique was suitable for fortified soil samples with the recoveries ranging from 80% to 130%. These methods were then used to extract and determine the level of imazapyr and imazapic in the subsequent studies. Analysis of water samples showed that there were no traces of imazapyr and imazapic residues after 120 days from their single application. However, their leftovers were still detected at three different soil depths with half-lives between 24 to 186 days. The GUS index showed that imazapyr and imazapic are leacher herbicides (>2.8), with capability to be mobile and leach further into deep soil. Adsorption-desorption study proved that imazapyr and imazapic were strongly adsorbed into soil containing higher clay, CEC and organic content (p90%). For the potential health studies, hazard index (HI) and hazard quotient (HQ) was less than 1, indicating that ingestion of imidazolinone-contaminated A. testudineus in six months period poses a low potential health risk. In conclusion, sorption and photodegradation of imazapyr and imazapic were greatly affecting the behaviour of these herbicides in water and soil. Hence, the results from this study can provide a fundamental scientific evidence and information regarding the concentration and behaviour of imazapyr and imazapic herbicides in Malaysian paddy soil and water. The optimized extraction and detection methods obtained in this study can be used by other researchers and regulatory agencies for routine monitoring of these herbicides in the environment

Exploration of microplastics from personal care and cosmetic products and its estimated emissions to marine environment: An evidence from Malaysia

This study aims understand microplastics from personal care and cosmetic products in Malaysia via quantification and characterization of microplastics together with emission estimation to marine environment. A total of 214 respondents from all over Malaysia were surveyed with identification of top ten personal care and cosmetic products usage. Particles found in facial cleaner/scrub and toothpaste were colored and colorless with majority of granular shapes. Particles in toothpaste were found between 3 and 145 μm while particles in facial cleaner/scrub were found to be between 10 and 178 μm, stipulating the presence of microplastics. Plastic polymers (LDPE and polypropylene) were found in all facial cleaner/scrub samples while only plastic polymers (LDPE) were present in toothpaste sample G. A total of 0.199 trillion microplastics are expected to be released annually to marine environment in Malaysia. Personal care and cosmetic products are seen as one of the microplastics sources for Malaysia and worldwide

Pharmaceuticals residues in selected tropical surface water bodies from Selangor (Malaysia): occurrence and potential risk assessments

This study investigated the occurrence of nine pharmaceuticals (amoxicillin, caffeine, chloramphenicol, ciprofloxacin, dexamethasone, diclofenac, nitrofurazone, sulfamethoxazole, and triclosan) and to evaluate potential risks (human health and ecotoxicological) in Lui, Gombak and Selangor (Malaysia) rivers using commercial competitive Enzyme-Linked Immunosorbent Assay (ELISA) kit assays. Physicochemical properties of these rivers showed the surface samples belong to Class II of Malaysian National Water Quality Standards which requires conventional treatment before consumption. All the pharmaceuticals were detected in all three rivers except for triclosan, dexamethasone and diclofenac which were not detected in few of sampling locations in these three rivers. Highest pharmaceutical concentrations were detected in Gombak river in line of being as one of the most polluted rivers in Malaysia. Ciprofloxacin concentrations were detected in all the sampling locations with the highest at 299.88 ng/L. While triclosan, dexamethasone and diclofenac concentrations were not detected in a few of sampling locations in these three rivers. All these nine pharmaceuticals were within the levels reported previously in literature. Pharmaceutical production, wastewater treatment technologies and treated sewage effluent were found as the potential sources which can be related with pharmaceuticals occurrence in surface water samples. Potential human risk assessment showed low health risk except for ciprofloxacin and dexamethasone. Instead, ecotoxicological risk assessment indicated moderate risks were present for these rivers. Nevertheless, results confirmation using instrumental techniques is needed for higher degree of specificity. It is crucial to continuously monitor the surface water bodies for pharmaceuticals using a cost-effective prioritisation approach to assess sensitive sub-populations risk

Evaluating the growth and development of black soldier fly (BSF) (Hermetia illucens (L.) (DIPTERA: STRATIOMYIDAE) larvae reared on different agricultural waste materials

The black soldier fly (BSL), Hermetia illucens (L.), is a beneficial insect that helps manage high concentrations of animal manure and other biosolids in tropical and warm-temperate areas. Bioremediation with black soldier fly larvae (BSFL) can turn biosolids into high-value biomass (proteins, oils, lipids, and chitin). This study explored the effects of three agricultural wastes as feedstocks for the growth and development of BSFL. A total of 1000 7-day-old BSFLs were reared separately in containers containing either palm kernel extract (PKE), soybean waste (SW), or coconut milk waste (CMW). The effect of feeding substrate on larval growth and development was determined for ten days by daily measurements of the BSFL’s length and weight. BSFL reared on PKE substrate resulted in the highest mean length (22.67±2.31 mm) and weight growth (0.27±0.02 g), followed by BSFL reared on SW (length: 18.67±1.53 mm; weight: 0.20±0.02 g) and CMW (length: 18.33±0.58mm; weight: 0.15±0.01 g). Bioconversion rate of BSFL was also found to differ across treatments; BSFL reared on PKE grows and converts substrates twice as fast as those fed on SW or CMW. This work then examines the effects of several SW:PKE ratios (20:80; 80:20; 30:70; 70:30 and 50:50) on BSFL growth. The weight (0.28±0.04 g) and length (22.67±2.52 mm) of BSFL were highest when SW:PKE ratio of 80:20 is used. High content of SW resulted in a significant increase in BSFL length (6.76%-15.25%) and weight (23.54%-64.71%). Therefore, it can be concluded that substrate feed type has a substantial effect on BSFL’s growth and development