title: Systematic and day-to-day effects of chemical-derived population estimates on wastewater-based drug epidemiology.
abstract: Population size is crucial when estimating population-normalized drug consumption (PNDC) from wastewater-based drug epidemiology (WBDE). Three conceptually different population estimates can be used: de jure (common census, residence), de facto (all persons within a sewer catchment), and chemical loads (contributors to the sampled wastewater). De facto and chemical loads will be the same where all households contribute to a central sewer system without wastewater loss. This study explored the feasibility of determining a de facto population and its effect on estimating PNDC in an urban community over an extended period. Drugs and other chemicals were analyzed in 311 daily composite wastewater samples. The daily estimated de facto population (using chemical loads) was on average 32% higher than the de jure population. Consequently, using the latter would systemically overestimate PNDC by 22%. However, the relative day-to-day pattern of drug consumption was similar regardless of the type of normalization as daily illicit drug loads appeared to vary substantially more than the population. Using chemical loads population, we objectively quantified the total methodological uncertainty of PNDC and reduced it by a factor of 2. Our study illustrated the potential benefits of using chemical loads population for obtaining more robust PNDC data in WBDE.
authors.forename: Foon Yin
authors.initials: FY
authors.lastname: Lai
authors.forename: Shalona
authors.initials: S
authors.lastname: Anuj
authors.forename: Raimondo
authors.initials: R
authors.lastname: Bruno
authors.forename: Steve
authors.initials: S
authors.lastname: Carter
authors.forename: Coral
authors.initials: C
authors.lastname: Gartner
authors.forename: Wayne
authors.initials: W
authors.lastname: Hall
authors.forename: K Paul
authors.initials: KP
authors.lastname: Kirkbride
authors.forename: Jochen F
authors.initials: JF
authors.lastname: Mueller
authors.forename: Jake W
authors.initials: JW
authors.lastname: O'Brien
authors.forename: Jeremy
authors.initials: J
authors.lastname: Prichard
authors.forename: Phong K
authors.initials: PK
authors.lastname: Thai
authors.forename: Christoph
authors.initials: C
authors.lastname: Ort
mesh_terms: D019352:Censuses; D006801:Humans; D013287:Illicit Drugs / Q000032:analysis*; D011156:Population Density; D011793:Queensland / Q000453:epidemiology; D012621:Seasons; D012722:Sewage / Q000737:chemistry; D015813:Substance Abuse Detection / Q000379:methods / Q000706:statistics & numerical data; D019966:Substance-Related Disorders / Q000453:epidemiology*; D035501:Uncertainty; D014505:Urban Population; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D013287:Illicit Drugs; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical