Metformin is the most widely used drug to treat type 2 diabetes. Monitoring spatial patterns of metformin use could provide new insights into treatment of type 2 diabetes and the distribution among populations. This study applied a wastewater-based epidemiological (WBE) approach to estimate metformin use in different populations across Australia and compared these estimates with traditional approaches of surveys and prescription data. Twenty-four-hour influent samples were collected from 75 wastewater treatment plants (WWTPs) across Australia in 2016 and analysed for metformin. Metformin was detected in all samples ranging in concentration from 8.2 to 191 µg/L (median 58 µg/L). Concentrations were converted to population-weighted average consumption at the national level, resulting in an average consumption of 28.6 g/day/1000 people across Australia, which was within 7% of estimates from national prescription statistics. In addition, results for five out of seven states had an estimated prevalence of type 2 diabetes within 20% compared to the traditional epidemiology surveys. Spatial patterns were also observed between urban and rural settings, with higher consumption rates of metformin found in Major Cities (22.5 ± 10.9 g/d/1000 people) and Inner Regional cities (25.4 ± 13.4 g/d/1000 people) than in Outer Regional (17.0 ± 8.1 g/d/1000 people) and Remote areas (15.1 ± 7.4 g/d/1000 people). Consumption estimates were also correlated against socioeconomic factors of the specific catchment areas. Greater metformin use was correlated with populations of lower education and income levels, while positive correlations were found between metformin consumption and consumption of allopurinol, caffeine and venlafaxine. Our study provides more evidence on the distribution of metformin use across Australia, which can be used to develop public health strategies to reduce the overall burden of type 2 diabetes in specific regions.

Allergies have become an important public health issue as their occurrence is reportedly on the rise around the world. Exposure to environmental factors is considered as trigger for allergic diseases. However, there was limited data on the importance of each factor, particularly in China. In this study, we aimed to investigate the association between occurrence of allergic diseases with exposure to multiple environmental factors via wastewater surveillance across 28 cities in China. The surveillance was conducted by measuring biomarkers of proxies of allergic diseases, i.e. antihistamines, asthma drug, and of smoking, i.e. cotinine in wastewater. Data of green space and air quality were also collected. We observed the level of antihistamine use were significantly associated with smoking, green space and pollen but not significant with air pollution. People in Northern China used more antihistamines than their compatriots in Southern China, an observation aligning with previous reporting of more allergy prevalence in the North than the South of China. Our study affirmed that in China smoking is responsible for a rise in allergy and asthma in the population. Meanwhile, selected sensitizing pollens (occurring during summer) could have stronger impact to trigger allergies than other pollens (occurring in winter).