Luigi Lopardo

Measuring biomarkers in wastewater as a new source of epidemiological information: Current state and future perspectives

The information obtained from the chemical analysis of specific human excretion products (biomarkers) in urban wastewater can be used to estimate the exposure or consumption of the population under investigation to a defined substance. A proper biomarker can provide relevant information about lifestyle habits, health and wellbeing, but its selection is not an easy task as it should fulfil several specific requirements in order to be successfully employed. This paper aims to summarize the current knowledge related to the most relevant biomarkers used so far. In addition, some potential wastewater biomarkers that could be used for future applications were evaluated. For this purpose, representative chemical classes have been chosen and grouped in four main categories: (i) those that provide estimates of lifestyle factors and substance use, (ii) those used to estimate the exposure to toxicants present in the environment and food, (iii) those that have the potential to provide information about public health and illness and (iv) those used to estimate the population size. To facilitate the evaluation of the eligibility of a compound as a biomarker, information, when available, on stability in urine and wastewater and pharmacokinetic data (i.e. metabolism and urinary excretion profile) has been reviewed. Finally, several needs and recommendations for future research are proposed.

New Analytical Framework for Verification of Biomarkers of Exposure to Chemicals Combining Human Biomonitoring and Water Fingerprinting

Molecular epidemiology approaches in human biomonitoring are powerful tools that allow for verification of public exposure to chemical substances. Unfortunately, due to logistical difficulties and high cost, they tend to evaluate small study groups and as a result might not provide comprehensive large scale community-wide exposure data. Urban water fingerprinting provides a timely alternative to traditional approaches. It can revolutionize the human exposure studies as urban water represents collective community-wide exposure. Knowledge of characteristic biomarkers of exposure to specific chemicals is key to the successful application of water fingerprinting. This study aims to introduce a novel conceptual analytical framework for identification of biomarkers of public exposure to chemicals via combined human metabolism and urban water fingerprinting assay. This framework consists of the following steps: (1) in vitro HLM/S9 assay, (2) in vivo pooled urine assay, (3) in vivo wastewater fingerprinting assay, (4) analysis with HR-MSMS, (5) data processing, and (6) selection of biomarkers. The framework was applied and validated for PCMC (4-chloro-m-cresol), household derived antimicrobial agent with no known exposure and human metabolism data. Four new metabolites of PCMC (hydroxylated, sulfated/hydroxylated, sulfated PCMC, and glucuronidated PCMC) were identified using the in vitro HLM/S9 assay. But only one metabolite, sulfated PCMC, was confirmed in wastewater and in urine. Therefore, our study confirms that water fingerprinting is a promising tool for biomarker selection and that in vitro HLM/S9 studies alone, although informative, do not provide high accuracy results. Our work also confirms, for the first time, human internal exposure to PCMC.

Stereochemistry of ephedrine and its environmental significance: Exposure and effects directed approach

Analysis of drugs and pharmaceuticals in the environment is typically performed with non-chiral chromatographic techniques. The environmental risks posed by chiral compounds analysed in this way must therefore be assumed to be independent of chirality, meaning that each enantiomer is equally potent in toxicity and long-lived in stability. This manuscript examines the degradation of each of the four isomers of ephedrine in river simulating microcosms and links this to toxicity data obtained by exposing three different organisms (D. magna, P. subcapitata and T. thermophila) to each of the isomers individually. Microcosms showed that significant degradation only occurred in biotic conditions and that only two isomers (1R,2S-(-)-ephedrine, 1S,2S-(+)-pseudoephedrine) degraded significantly over a period of fourteen days. This is concerning because at least one of the non-degraded isomers (1S,2R-(+)-ephedrine) has been observed in wastewater effluent, which discharges directly into rivers, meaning these isomers could be persistent in the environment. We also observed formation of 1S,2R-(+)-ephedrine in single isomer 1R,2S-(-)-ephedrine river simulating microcosms. Human liver microsome assays and mass spectrometry based data mining revealed that 1S,2R-(+)-ephedrine is not human derived but it could be formed as a results of microbial metabolic processes. Across all three organisms tested the persistent isomers (1S,2R-(+)-ephedrine and 1R,2R-(-)-pseudoephedrine) were more toxic than those that undergo degradation; meaning that if these isomers are entering or formed in the environment they might represent a potentially hazardous contaminant.

Assessment of bisphenol-A in the urban water cycle.

The plasticizer bisphenol-A (BPA) is common to municipal wastewaters and can exert toxicity to exposed organisms in the environment. Here BPA concentration at 5 sewage treatment works (STW) and distribution throughout a river catchment in South West UK were investigated. Sampling sites included influent and effluent wastewater (n = 5), river water (n = 7) and digested sludge (n = 2) which were monitored for 7 consecutive days. Findings revealed average BPA loads in influent wastewater at two STWs were 10-37 times greater than the other wastewaters monitored. Concentrations up to ~100 μg L-1 were measured considerably higher than previously reported for municipal wastewaters. Temporal variability throughout the week (i.e., highest concentrations during weekdays) suggests these high concentrations are linked with industrial activity. Despite ≥90% removal during wastewater treatment, notable concentrations remained in tested effluent (62-892 ng L-1). However, minimal impact on BPA concentrations in river water was observed for any of the effluents. The maximum BPA concentration found in river water was 117 ng L-1 which is considerably lower than the current predicted no effect concentration of 1.6 μg L-1. Nevertheless, analysis of digested sludge from sites which received these elevated BPA levels revealed average concentrations of 4.6 ± 0.3 and 38.7 ± 5.4 μg g-1. These sludge BPA concentrations are considerably greater than previously reported and are attributed to the high BPA loading in influent wastewater. A typical sludge application regime to agricultural land would result in a predicted BPA concentration of 297 ng g-1 in soil. Further studies are needed on the toxicological thresholds of exposed terrestrial organisms in amended soils to better assess the environmental risk here.