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BACKGROUND AND AIMS: Illicit drug consumption is associated with public health effects and criminal activities. This study aimed to estimate Illicit drug consumption and annual market in the Netherlands from wastewater analysis of drug residues. METHODS: Residues of cocaine, amphetamine and 3,4-methylene dioxymethamphetamine (MDMA) were measured between 2015 and 2022 in 30 Dutch wastewater treatment plants serving both rural and urban populations. These wastewater treatment plants covered 20% of the total Dutch population. The Dutch annual retail market was estimated by extrapolating consumption to the total Dutch population, back-calculating consumption volume, correcting for drug purity and street price collected in voluntary checking services, and accounting for the correlation of consumption and urbanity. RESULTS: The per capita MDMA and cocaine consumption correlated positively with the urbanity of the wastewater treatment plant catchments with r2 of 31% and 64%, respectively. Amphetamine did not show a significant correlation with urbanity. The three studied drugs were conservatively estimated to cover an average annual market value of 903 (95% prediction interval 829 to 987) million Euro for the studied period. Market estimations from prevalence figures and interceptions of international trade were similar. CONCLUSIONS: Illicit drug consumption in the Netherlands appears to correlate positively with urban (in contrast to rural) areas. Wastewater analysis can be used to estimate the volume and monetary value of illicit drug markets as a proof of concept.
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Recent research in island biogeography has highlighted the important role of late Quaternary sea-level fluctuations in shaping biogeographic patterns in insular systems but focused on oceanic systems. Through this study, we aim investigate how late Quaternary sea-level fluctuations shaped species richness patterns in continental-shelf island systems. Focusing on the Aegean archipelago, we first compiled maps of the area's geography using published data, under three sea-level stands: (a) current; (b) median sea-level over the last nine glacial-interglacial cycles (MSL); and (c) Last Glacial Maximum (LGM). We gathered taxon-island occurrences for multiple chorotypes of angiosperms, butterflies, centipedes, and reptiles. We investigated the impact of present-day and past geographic settings on chorological groups by analyzing island species-area relationships (ISARs) and using generalized linear mixed models (GLMMs) selection based on multiple metrics of goodness of fit. Our results confirm that the Aegean's geography has changed dramatically since the LGM, whereas the MSL only modestly differs from the present configuration. Apart for centipedes, paleogeographic changes affected both native and endemic species diversity through altering connections between land-bridge islands and the mainland. On land-bridge islands, we detected over-representation of native species and under-representation of endemics. Unlike oceanic islands, sea-level-driven increase of isolation and area contraction did not strongly shape patterns of species richness. Furthermore, the LGM configurations rather than the MSL configuration shaped patterns of endemic species richness. This suggests that even short episodes of increased connectivity with continental populations are sufficient to counteract the genetic differentiation of insular populations. On the other hand, the over-representation of native nonendemic species on land-bridge islands reflected MSL rather than LGM mainland connections. Our study shows that in terms of processes affecting species richness patterns, continental archipelagos differ fundamentally from oceanic systems because episodic connections with the mainland have profound effects on the biota of land-bridge islands.