Q. What is the Consumption estimate [mg/1000 people/day]?
Estimated consumption is measured in milligrams per 1,000 people per day. We calculate consumption by normalizing wastewater concentration (determined by mass spectrometry) to flow and population indicated in sample logs. Non-detects or values below the batch-specific instrument detection limit are set to NA.
Q. What is wastewater concentration [ng/L]?
Concentration of a given analyte in nanograms per liter, as determined by mass spectrometry.
Q. How do we know if any changes we see in our data are due to true increases in consumption?
We recommend looking across a minimum of 3-4 weekly samples in order to determine whether changes in consumption over time constitute a consistent trend. This is especially critical in smaller (<10,000 people) catchment areas, which tend to have much higher sampling variability than larger catchments. Large, single-sample spikes, however, can be attributed to three potential sources of variation.
- True spikes in consumption. Drastic increases in wastewater estimates of both parent drugs and their associated metabolites are typically indicative of increases in substance use. These spikes may be caused by concerts, festivals, or other events associated with increased substance use and/or the influx of travelers into a wastewater catchment area. Additionally, consumption estimates for certain drug types may vary drastically depending on the days of the week on which samples are taken. For example, numerous wastewater studies have shown that cocaine consumption increases substantially over the weekend before declining to lower levels during the middle of the week.
- Dumping events. Sharp increases in wastewater estimates of parent drugs, but not the associated metabolites, may highlight mass dumping events, such as people flushing contaminated or otherwise unwanted supplies of drugs down toilets . These spikes typically represent environmental contamination rather than human consumption.
- Analytic variability. While variability associated with Biobot’s laboratory methods is expected to be very low, it is possible that sample-to-sample changes may be attributable to error in the solid phase extraction or LC/MS processes. The lab team has and will continue to run quality assurance experiments to ensure that analytic variability stays within established ranges of acceptable variation, and all data undergo rigorous quality control processes prior to their release to ensure their validity. We therefore believe the contribution of analytic error to any large sample-to-sample changes to be minimal.
Q. Why is there no fentanyl detection in my community despite an opioid crisis?
Although fentanyl is responsible for tens of thousands of deaths across the country each year, fentanyl use remains rare among the general population. Additionally, fentanyl is a highly potent synthetic opioid and is used in extremely small amounts, often weighing less than 1 milligram. If use is very low in your community, fentanyl and its metabolite, norfentanyl, may not be detectable in all of your wastewater samples.
Q. At what point do the data/numbers indicate concerns? What is the threshold of concern?
The risks posed by high risk substance use can vary widely between communities and can be dependent upon naloxone availability, substance use disorder treatment availability, and general access to healthcare. Biobot therefore recommends that communities integrate wastewater data on high risk substances into their broader substance use data sources, including overdose data, to better understand how estimates of community substance use related to outcomes of interest.