Bioplastic packaging in circular economy: A systems-based policy approach for multi-sectoral challenges.

Bioplastics have long been publicized as a sustainable plastic packaging alternative; however, their widespread industrialization is still embryonic due to complex challenges spanning multiple sectors. This review critically analyses the bioplastic lifecycle and provides a holistic evaluation of both the opportunities and potential trade-offs along their value chain. Their lifecycle is divided into three sectors: 1) resources, extraction, and manufacturing, 2) product consumption which discusses availability, consumer perception, and marketing strategies, and 3) end-of-life (EoL) management which includes segregation, recycling, and disposal. In the production phase, the primary challenges include selection of suitable raw feedstocks and addressing the techno-economic constraints of manufacturing processes. To tackle these challenges, it is recommended to source sustainable feedstocks from innovative, renewable, and waste materials, adopt green synthesis mechanisms, and optimize processes for improved efficiency. The consumption phase encompasses challenges related to market availability, cost competitiveness, and consumer perception of bioplastics. Localizing feedstock sourcing and production, leveraging the economics of scale, and promoting market demand for recycled bioplastics can positively influence the market dynamics. Additionally, dispelling misconceptions about degradability through proper labeling, and employing innovative marketing strategies to enhance consumer perception of the mechanical performance and quality of bioplastics is crucial. During the EoL management phase, major challenges include inadequate awareness, inefficient segregation protocols, and bioplastics with diverse properties that are incompatible with existing waste management infrastructure. Implementing a standardized labeling system with clear representation of suitable EoL techniques and integrating sensors and machine learning-based sorting technologies will improve segregation efficiency. Further, establishing interconnected recycling streams that clearly define the EoL pathways for different bioplastics is essential to ensure circular waste management systems. Finally, designing a comprehensive systems-based policy framework that incorporates technical, economic, environmental, and social drivers is recommended to promote bioplastics as a viable circular packaging solution.

Leaching of organic matter from cigarette butt filters as a potential disinfection by-products precursor.

The study aimed to evaluate cigarette butt filters (CBFs) as a potential source of dissolved organic carbon (DOC) in water leading to the formation of disinfection by-products. Two different forms of CBFs - intact (I) and disintegrated (D), as they occur in the environment, were selected for leaching in chlorinated (CI, CD), non-chlorinated (NI, ND), and highly chlorinated (HCD) water samples. The UV absorbance profiles of the leachate samples showed that intact CBFs exhibited higher DOC leaching compared to the disintegrated ones, which was further accentuated in chlorinated samples (CI > CD > NI > ND). The Fourier Transform Infrared spectra of the leachates revealed the presence of characteristic functional groups of cellulose acetate and its chlorinated derivatives, indicating the potential degradation of the polymer. Moreover, trihalomethane (THM) formation in chlorinated samples was relatively higher in CI samples (2 - 11.5 times) compared to CD, consistent with the DOC leaching trends. Further, the speciation characteristics of different THMs in both CI and CD samples were similar. Although spectral and morphological analyzes of CI and CD samples revealed negligible variation, HCD samples depicted significant surface roughness characterized by the formation of pits and holes, along with the evolution of crystallinity. This suggested accelerated degradation of CBFs and disruption of acetyl groups as a factor of elevated chlorine concentrations.

Phytotoxicity of trihalomethanes and trichloroacetic acid on Vigna radiata and Allium cepa plant models.

Disinfection by-products (DBPs) are a concern due to their presence in chlorinated wastewater, sewage treatment plant discharge, and surface water, and their potential for environmental toxicity. Despite some attention to their ecotoxicity, little is known about the phytotoxicity of DBPs. This study aimed to evaluate the individual and combined phytotoxicity of four trihalomethanes (THMs: trichloromethane (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and tribromomethane (TBM) and their mixture (THM4)), and trichloroacetic acid (TCAA) using genotoxic and cytotoxic assays. The analysis included seed germination tests using Vigna radiata and root growth tests, mitosis studies, oxidative stress response, chromosomal aberrations (CA), and DNA laddering using Allium cepa. The results showed a progressive increase in root growth inhibition for both plant species as the concentration of DBPs increased. High concentrations of mixtures of four THMs resulted in significant (p < 0.05) antagonistic interactions. The effective concentration (EC50) value for V. radiata was 5655, 3145, 2690, 1465, 3570, and 725 mg/L for TCM, BDCM, DBCM, TBM, THM4, and TCAA, respectively. For A. cepa, the EC50 for the same contaminants was 700, 400, 350, 250, 450, and 105 mg/L, respectively. DBP cytotoxicity was observed through CAs, including C-metaphase, unseparated anaphase, lagging chromosome, sticky metaphase, and bridging. Mitotic depression (MD) increased with dose, reaching up to 54.4% for TCAA (50-500 mg/L). The electrophoresis assay showed DNA fragmentation and shearing, suggesting genotoxicity for some DBPs. The order of phytotoxicity for the tested DBPs was TCAA > TBM > DBCM > BDCM > THM4 > TCM. These findings underscore the need for further research on the phytotoxicity of DBPs, especially given their common use in agricultural practices such as irrigation and the use of sludge as manure.

Trihalomethane Cancer Risk Assessment for Private and Shared Residences: Addressing the Differences in Inhalation Exposure.

The multi-pathway cancer risk (CR) assessment of trihalomethanes (THM) involves considering exposure via ingestion, dermal contact, and inhalation. Inhalation occurs during showering due to the volatilization of THMs from chlorinated water to the air. When assessing inhalation risks, exposure models commonly assume that the initial THM concentration in the shower room is zero. However, this assumption is only valid in private shower rooms where single or infrequent showering events take place. It fails to account for continuous or successive showering events in shared showering facilities. To address this issue, we incorporated the accumulation of THM in the shower room air. We studied a community (population ≈ 20,000) comprising two types of residences with the same water supply: population A with private shower rooms, and population B with communal shower stalls. The total THM concentration in the water was 30.22 ± 14.45 µg L-1. For population A, the total CR was 58.5 × 10-6, including an inhalation risk of 1.11 × 10-6. However, for population B, the accumulation of THM in the shower stall air resulted in increased inhalation risk. By the tenth showering event, the inhalation risk was 2.2 × 10-6, and the equivalent total CR was 59.64 × 10-6. We found that the CR significantly increased with increasing shower duration. Nevertheless, introducing a ventilation rate of 5 L s-1 in the shower stall reduced the inhalation CR from 1.2 × 10-6 to 7.9 × 10-7.

Drinking hot beverages from paper cups: Lifetime intake of microplastics.

Microplastics (MPs) have been found in many packaged food products such as salt, tea bags, milk, and fish. In a previous study by this group, MPs were found to leach into hot water from the plastic lining of disposable paper cups. No studies were found in the literature quantifying health risks or lifetime intake of MPs. At present, it is not possible to quantify health risks due to MPs because dose-response and toxicity assessments are not available. Therefore, the objective of the current study was to assess the intake of MPs and associated contaminants like fluoride that are released into these hot beverages. MPs in the previous study were quantified in terms of particle counts only and a simple method was adopted in the present study to convert the microplastics count into its respective mass. Chronic daily intake (CDI) and lifetime intake (LTI) of MPs through the ingestion pathway were calculated. CDI and Hazard Quotient (HQ) due to fluoride ingestion were also estimated following USEPA guidelines. Monte Carlo (MC) simulations were used to account for the variability in input variables such as concentration of MPs, body weight, averaging time, exposure duration, exposure frequency and ingestion rate to evaluate the impact on CDI and LTI values. The CDI was used to estimate the LTI of MPs and HQ for fluoride ingestion. MC simulations with 100,000 iterations resulted in an average CDI of 0.03 ± 0.025 mg of microplastic per kg of body weight per day and 7.04 ± 8.8 µg fluoride per kg body weight per day. This study takes us one step closer to estimating the human health risk due to the ingestion of microplastics and other contaminants through food items.

Probabilistic approach for health hazard assessment of trihalomethanes through successive showering events.

Trihalomethanes (THMs) are common disinfection by-products in chlorinated tap waters. They can cause various cancers and non-cancer health hazards. Ingestion, dermal contact, and inhalation are the three exposure routes considered in the THM hazard or risk assessments. Among these, inhalation hazard is generally calculated by assuming the initial concentration as zero. This assumption fails to address the case of continuous or successive showers that can happen in shared showering facilities such as student hostels or gymnasiums. In the present study, the leftover THM concentration from the previous bath was considered to assess the chronic daily intakes (CDI) and hazard index (HI) for successive showers. For this, tap water of a university campus was analyzed to understand the extent of THM exposure at consumer points and the result obtained was used for the hazard assessment. Total THM concentrations varied from 0.51 to 68.9 µg L-1. To address the variability of the model input parameters, 50,000 iterations of Monte Carlo simulation were carried out. Maximum HI values of 7.94E - 02 ± 3.63E - 02, and 6.69E - 02 ± 3.08E-02 were observed for the 1st shower for females and males, respectively. This value increased exponentially up to the 5th shower and thereafter, the value was constant. The methodology followed in the present study successfully determines the risk and hazard of THMs through successive showers.

Environmental impacts of the widespread use of chlorine-based disinfectants during the COVID-19 pandemic.

Chlorinated disinfectants are widely used in hospitals, COVID-19 quarantine facilities, households, institutes, and public areas to combat the spread of the novel coronavirus as they are effective against viruses on various surfaces. Medical facilities have enhanced their routine disinfection of indoors, premises, and in-house sewage. Besides questioning the efficiency of these compounds in combating coronavirus, the impacts of these excessive disinfection efforts have not been discussed anywhere. The impacts of chlorine-based disinfectants on both environment and human health are reviewed in this paper. Chlorine in molecular and in compound forms is known to pose many health hazards. Hypochlorite addition to soil can increase chlorine/chloride concentration, which can be fatal to plant species if exposed. When chlorine compounds reach the sewer/drainage system and are exposed to aqueous media such as wastewater, many disinfection by-products (DBPs) can be formed depending on the concentrations of natural organic matter, inorganics, and anthropogenic pollutants present. Chlorination of hospital wastewater can also produce toxic drug-derived disinfection by-products. Many DBPs are carcinogenic to humans, and some of them are cytotoxic, genotoxic, and mutagenic. DBPs can be harmful to the flora and fauna of the receiving water body and may have adverse effects on microorganisms and plankton present in these ecosystems.