Occurrence and Control of Genotoxins in Drinking Water: A Monitoring Proposal

Endocrine disrupting chemicals in Italian drinking water systems: Insights from a three-year investigation combining chemical and effect-based tools

Drinking water quality can be compromised by endocrine-disrupting chemicals (EDCs). Three phenolic compounds [bisphenol A (BPA), nonylphenol (NP), and 4-octylphenol (OP)] and three hormones [17β-estradiol (E2), estrone (E1), and 17α-ethinylestradiol (EE2)] were analyzed as EDCs potentially occurring in source and drinking water from three full-scale drinking water treatment plants (DWTPs) in the Romagna area (Italy) by a combined approach of HPLC-MS/MS target analysis and effect-based tests for estrogenicity and genotoxicity. The EDC removal efficiency was evaluated at different steps along the treatment process in the most advanced DWTP. NP prevailed in all samples, followed by BPA. Sporadic contamination by OP and E1/E2 appeared only in the source waters; EE2 was never detected. No estrogenic or genotoxic activity was found, except for two samples showing estrogenicity well below the effect-based trigger value suggested for drinking water safety (0.9 ng/L EEQ). BPA and NP levels were largely below the threshold value; however, increases were observed after the intermediate steps of the treatment chain. The good quality of the water relied on the last step, i.e. the activated carbon filtration. DWTPs may represent an extra source of EDCs and monitoring chemical occurrence at all steps of the process is advisable to improve efficiency.

Using Pgst-4::GFP-transformed Caenorhabditis elegans for drinking water quality monitoring

Biological effect-based monitoring is essential for predicting or alerting to a possible deterioration in drinking water quality. In the present study, a reporter gene assay based on oxidative stress-mediated Pgst-4::GFP induction in the Caenorhabditis elegans strain VP596 (VP596 assay) was assessed for its applicability in evaluating drinking water safety and quality. This assay was used to measure the oxidative stress response in VP596 worms exposed to six ubiquitous components (As³⁺, Al³⁺, F^-, NO₃^--N, CHCl₃, and residual chlorine) in drinking water, eight mixtures of these six components designed through orthogonal design, ninety-six unconcentrated water samples from source to tap water in two supply systems, and organic extracts (OEs) of twenty-five selected water samples. Pgst-4::GFP fluorescence was not induced by Al³⁺, F^-, NO₃^--N, and CHCl₃, and was significantly enhanced by As³⁺ and residual chlorine only at concentrations higher than their respective drinking water guideline levels. Pgst-4::GFP induction was not detected in any of the six-component mixtures. Induction of Pgst-4::GFP was observed in 9.4% (3/32) of the source water samples but not in the drinking water samples. However, a notable induction effect was revealed in the three OEs of drinking water, with a relative enrichment factor of 200. These results suggest that the VP596 assay has limited utility for screening drinking water safety by testing unconcentrated water samples; however, it offers a supplemental in vivo tool for prioritizing water samples for an enhanced quality assessment, monitoring pollutant removal performance by drinking water treatment plants, and evaluating water quality in water supplies.

Assessment of genotoxic potential of the treated hospital wastewater using cytogenetic assays

The cytogenetic study using hospital effluent was carried out engaging three cytogenetic end points—chromosomal aberration (CA) assay, mitotic indices (MIs), and micronucleus (MN) Analysis. These bioassays were performed in hematopoietic bone marrow cells of Mus musculus. The experiment commenced with the collection of hospital effluent from the final outlet when wastewater gets collected after undergoing treatment by a multistep process. The pure treated sample water was collected at different times between March 2019 to January 2020 and was given ad libitum to mice at its low (90% dilution) and high (pure form), i.e. 100% concentration for 3 different durations i.e. 7, 15, and 30 days, respectively. The results indicated a significant (P < 0.01) decrease in the MI in all the groups but was more pronounced in the group which was given 100% concentrated sample water collected in the month of March 2019. Besides this, the major finding was presence of CAs like breaks, fragments, rings, and pulverization in bone marrow cells in different groups; however, the frequency of these aberrations varied from group to group. A significant (P < 0.01) increase in MN Induction and decreased ratio (P < 0.01) of polychromatic to normonochromatic erythrocytes were observed in samples collected in month of March both at 10% and 100% concentrations. However, decrease in the ratio was observed in the samples of September and January at low-concentration sample water. The results thus indicated that there was some lacuna in the treatment process earlier in the month of March, which was rectified to some extent in the subsequent months. Hence, the treated wastewater collected in the month of January next year was more suitable for its use than other samples. Summary: These findings thus draw attention toward ensuring efficiency of the treatment plant and quality of water by the hospital management before it being disposed off into the municipal supply; a step that can help society to live a healthy life. With these findings, it is conveyed that all the hospitals, diagnostic labs, and other health care establishments must pay utmost attention at liquid waste disposal mechanism to make environment pollution-free.

Contaminants of emerging concern in drinking water: Quality assessment by combining chemical and biological analysis

Drinking water quality is a priority issue of the environmental policy agenda, however regulation on Contaminants of Emerging Concern (CECs) is limited. A proposal to revise the Drinking Water Directive has recently been approved (EU Council 2020), which updates the quality standards and introduces the watch list mechanism, including for the first time endocrine disruptors and pharmaceuticals. The purpose of this study was to evaluate the occurrence of selected CECs in surface water at the entrance of drinking water treatment plants (DWTPs) and in treated water, ready for distribution in the network. Samples were collected at three different DWTPs (Italy) and CECs assessed by LC-MS/MS were the following: bisphenol A (BPA), nonylphenol (NP), octylphenol, perfluorooctanesulfonic and perfluorooctanoic acids (PFOS and PFOA), atenolol, caffeine (CFF), carbamazepine (CBZ), estrone, 17-β-estradiol, 17-α-ethinyl estradiol, diclofenac, and ibuprofen. In addition, biological analyses were performed to ascertain cumulative estrogenic and/or genotoxic potential of the samples. CFF, NP, PFOA, BPA, and CBZ were the most frequently detected contaminants, found in treated water in the following ranges: CFF 12.47-66.33 ng/L, NP 7.90-53.62 ng/L, PFOA <LOQ-12.66, ng/L, BPA <LOQ-6.27 ng/L, and CBZ <LOQ-1.20 ng/L. While treatments were generally efficacious in reducing BPA, CFF and CBZ, they were sometimes ineffective for NP and PFOA. According to the low concentrations and/or regulation limit for each single contaminant, the water analyzed met the criteria of good quality. No estrogenic or genotoxic activities were induced by the water assessed, with the exception of one sample. It has been suggested that drinking water may not represent a significant source of human exposure to CECs, however co-occurrence of different compounds may lead to additive/synergistic interactions causing unexpected effects on human health and the environment, and deserve implementation of strategies for detection and removal.

The release of contaminants from steel slags and natural aggregates: Evaluation of toxicity and genotoxicity

Steel slags (SS) are the major waste produced by iron and steel industry. Slags may be reused as recycled materials, instead of natural aggregates (NA), to reduce the final disposal in a landfill and the exploitation of raw materials. However, the reuse of SS may generate a potential release of toxic compounds for the environment and humans. The purpose of this study was to evaluate the toxicity and genotoxicity of SS, in comparison with NA, by using an integrated chemical-biological approach to enable their safe reuse in engineering applications. Leaching solutions from samples were obtained by using short-term leaching tests (CEN EN 12457-2, 2004) usually adopted for the evaluation of waste recovery and final disposal. Chemical analyses of leachates were performed according to the Italian legislation on waste recovery (Ministerial Decree 186/2006). The leaching solutions were assayed by using toxicity test on Daphnia magna. Moreover, mutagenicity/genotoxicity tests on Salmonella typhimurium, Allium cepa, and human leucocytes and fibroblasts were carried out. The releases of pollutants from all samples were within the limits of the Italian legislation for waste recovery. Despite the effects that SS and NA could have on different cells, in terms of toxicity and genotoxicity, globally, SS do not seem to be any more hazardous than NA. This ecotoxicological assessment, never studied before, is important for promoting further studies that may support the decision-making process regarding the use of such types of materials.

Genotoxicity of source, treated and distributed water from four drinking water treatment plants supplied by surface water in Sardinia, Italy

High levels of disinfection by-products (DBPs) are constantly found in drinking water distributed in Sardinia, an Italian island with a tourist vocation and critical issues related to the drinking water supply. To reduce the concentration of trihalomethanes the disinfectant in use was changed - chlorine dioxide was adopted instead of hypochlorite. However, this caused the appearance of other DBPs (e.g., chlorites) in water distributed to the population. Thus, the use of monochloramine as a secondary disinfectant (associated with chlorine dioxide as the primary disinfectant) was evaluated in four drinking water treatment plants supplied by artificial basins located in the central-northern part of Sardinia. Raw, disinfected and distributed waters were studied for genotoxicity using a battery of in vitro tests on different cells (bacteria, plant and mammalian cells) to detect different genetic endpoints (i.e., point and chromosome mutations and DNA damage). Moreover, a chemical and microbiological characterisation of water samples was performed. All samples of water distributed to the people showed mutagenic or genotoxic effects in different cells/organisms. In particular, chromosome aberrations in plant cells and DNA damage in human cells were observed. In this study, the use of chloramines associated with other disinfectants did not eliminate the mutagenicity present in the raw water and when the raw water was not mutagenic it introduced mutagenic/genotoxic substances. A careful management of drinking water is needed to reduce health hazards associated with the mutagenicity of drinking water.

Environmental exposure and health effects in a highly polluted area of Northern Italy: a narrative review

Human health and well-being are strongly linked to the state of the environment. The high industrial pressure present in the Province of Brescia, located in Northern Italy, produced strong environmental and health concerns. This narrative review of the literature aims at identifying the studies focused on the association between exposure to environmental pollutants and health effects in the population living in this area. Thirteen papers fitted the inclusion criteria: five were focused on the connection among pollutants present in air matrix and health effects, seven on both air and soil, and one on soil. No study investigated the relationship with water pollution. The great variability in the analyzed end-points made it difficult to draw precise conclusions, but the fact that, in almost all the studies, the investigated health effects have a positive association with the exposure to different kinds of pollutants, allows us to hypothesize that the considered population is living in an area where the "environmental pressure" could produce significant health effects in the future.

Toxicological aspects of trihalomethanes: a systematic review

Chlorine is considered the most used chemical agent for water disinfection worldwide. However, water chlorination can lead to by-product generation which can be toxic to humans. The present study aimed to perform a systematic review on the toxicity of trihalomethanes (THMs) through bioindicators of cytotoxicity, genotoxicity, and mutagenicity. The results showed that studies on the effects of THMs on DNA are a current research concern for evaluating the toxicity of the pure compounds and real samples involving several types including water for recreational use, reused water, and drinking water. THMs deleterious effects have been assessed using several biosystems, where the Ames test along with experimental animal models were the most cited. A wide range of THM concentrations have been tested. Nevertheless, DNA damage was demonstrated, highlighting the potential human health risk. Among the studied THMs, chloroform presented a different action mechanism when compared with brominated THMs, with the former being cytotoxic while brominated THMs (bromodichloromethane, bromoform, and dibromochloromethane) were cytotoxic, genotoxic, and mutagenic. The described evidence in this research highlights the relevance of this topic as a human health issue. Nevertheless, research aimed to represent THMs current exposure conditions in a more accurate way would be needed to understand the real impact on human health.