Wastewater Based Epidemiology

Question 1

LO

Answer 1

• Wastewater-based epidemiology
• Benefits and limitations
• Methodology
• Case study: illicit drugs
• Other applications

Question 2

What are the different pathways in which chemicals can get into the environment?

Answer 2

Question 3

What is the definition of Wastewater-based epidemiology?

Answer 3

**Definition: **A methodology to identify and monitor community consumption and exposure to chemicals and other agents by analysis of municipal wastewater

Question 4

What are some urban sources to the exposure to humans via drinking water/ food etc?

Answer 4

Raw sewage
Ecotoxicity
Treated sewage
Sludge

• Assumption of raw sewage is it’s a diluted pooled urine sample of the population
• PFAS- chemical of concern (in London, originating from river and ending up in drinking water)

Question 5

What are the stages to the wastewater treatment process?

Answer 5

Question 6

What are the benefits of Water based epidemiology?

Answer 6

• Wastewater resembles a **pooled-urine sample **
• Uses waste material as an **intelligence resource **
• Can determine population activity, consumption, or exposure in **near real time **
• Possible to do qualitative (early warning) and quantitative (monitoring) analysis at scale
• Allows trends to be plotted spatiotemporally
• It is objective- does not suffer from participant bias or symptoms
• Can be applied to several different types of study (e.g., illegal drugs, alcohol, pesticide exposure anti-terror, disease, SARS-CoV-2, etc)

Question 7

What are the limitations of WBE?

Answer 7

*** Back calculation uncertainty **
o Population movement
o Sorption/ stability across different WWTPs
o Exfiltration (leaky pipes) e.g., London= 20%
o Metabolism- not all the same and administration routes combined/ different- LC-MS gives most certain results
o Quantification uncertainty (analysis)

• Generalisation to bigger (national) populations difficult from a few sites
• Ethics of WBE
• Determining licit/ illicit use of a substance
• Does not tell purity (though cutting agents can be measured too)
• Cannot tell number of people taking/ exposed to a substance
• Does not estimate **price **

Question 8

Chemical metabolism: what happens when we ingest them?

Answer 8

Question 9

Whats the Wastewater-based epidemiology process?

Answer 9

1. Sample collection (24h composite samples)
2. Analysis (e.g., SPE ad LC-MS/MS)
   SPE: Concentrates analytes, out of range of most LC-MS/MS sensitivity so need SPE
3. Loading (amount of target entering WWTP in g/day)
4. Consumption back calculation (amount of compound consumed/ exposed g/day)
5. Normalisation (per capita consumption or exposure in g/day/1000 people)
6. Doses per day (per capital dose/day/1000 people)

Question 10

When calculating a back calculation, what two formulas does it rely on and what are these?

Answer 10

Question 11

Answer 11

Question 12

What are the different types of analytical methods which can be used for WBE?

Answer 12

Solid phase extraction (SPE): used for concentration of trace analyte residues and matrix clean up

• Sampling can be done via **water or passive sampling **
• Passive sample is a chemical sponge, accumulates substances on surface, useful to detect new drugs in the community, drawback is the quantitative information, more qualitative screening tool
• 100 mL –> 100 µl, which is the typical volume being sampled in LC-MS
• Targeted analysis and quantification
  o Triple quadrupole in targeted mode in MS as these are good for quantitative measurements and are more sensitive, drawback= have to know what looking for
  o Parent mass and product ion, look at transmissions?? (look up)
• Untargeted analysis Suspect screening + ML
  o don’t need to know target

Question 13

What are the different types of mixed-mode SPE sorbents for chemical extraction? What are they used for?

Answer 13

• used for concentration of trace analyte residues and matrix clean up
• clean and concentrate sample
• HLB is a hydrophilic and lipophilic compound to ‘catch a bit of everything’- can have multiple interactions with this substrate
  *** Most drugs are cations **
• Strong cation exchanger is MCX and a weaker one is WCX
• Strong anion exchanger is MAX and a weak one is WAX
• Wastewater uses MCX as looking at the drugs which are cations

Question 14

What are the modes of SPE?

Answer 14

Matrix removal
Selective analyte extraction

Question 15

Tell me about matrix removal

Answer 15

Question 16

Tell me about selective analyte extraction

Answer 16

Question 17

Whats LC?

Answer 17

o Separation technique for liquid mixtures
o Sample injected onto a column and packed with sorbent particles (stationary phase)
o A flow of mobile phase flows over the stationary phase causing differential sorption and movement of analytes through the packed bed
o Overall, leads to separation of mixtures based on their affinity for both the stationary phase and mobile phase

Question 18

Whats MS?

Answer 18

o Detection technique that exploits the mass to charge ratio of a compound
o Can fragment ions in the MS to yield diagnostic ions for high assurance identification and quantification- this is called tandem MS
o Highly sensitive and deals with complex samples very well
o Can suffer from matrix effects which are compensated for using stable isotope internal standards
o Can be operated at standard or high resolution (140,000 fwhm and <5 ppm mass accuracy) for suspect screening
o Output is a “chromatogram” with separated compounds represented as “peaks” and can be represented in different formats
1. Total ion chromatogram
2. Extracted ion chromatogram
3. Reaction monitoring

Question 19

Why is method validation so important?

Answer 19

• An essential component to the WBE process- determines methods fitness for purpose
  * Follow a set of consensus guidelines e.g., FDA, ICH, Eurachem, OECD, etc
  * Matrix-matches standards used throughout
  * Component experiments: linearity, range, precision, accuracy, sensitivity (limits of detection/ quantification)

Question 20

What are some challenges of method validation?

Answer 20

*** Challenges **
o Very expensive and difficult to pass for 100+ compounds
o Several orders of magnitude needed from pg/L to µg/L
o Matrix effects and changing matrix
o Recovery
o Samples always positive- background correction needed
o Sample preparation and precision

Question 21

Whats are some current major challenges for environmental analysis?

Answer 21

Question 22

Over the years there have been instrumental method developments which has led to fast separations, tell me some of these methods developed and used?

Answer 22

Question 23

Geographical difference in illicit drug use exist

Answer 23

o Cocaine use highest in western and southern European cities, particularly in Belgium, the Netherland, Spain, and the UK. Wastewater analysis indicates that cocaine use is very low to negligible In the majority of eastern European cities
o Amphetamine varied considerable across study locations, with the highest levels reported in cities in the North and East of Europe. Amphetamine was found at much lower levels in cities in the south of Europe
o Methamphetamine (e.g., crystal meth) use, generally low and historically concentrated in the Czech Republic and Slovakia, now appears to be present also in Cyprus, the East of Germany and northern Europe. The observed methamphetamine loads in the other locations were very low to negligible. Both amphetamine and methamphetamine usage are stable
o For MDMA (e.g., ecstasy), the highest was Belgium, Germany, and the Netherlands. In general, it rose 2011-2016 and stable in 2017.
o Cocaine and MDMA loads were higher in large cities compared to smaller ones. No such differences could be detected for amphetamine and methamphetamine
o For London, the average estimated consumption is roughly 20-30 kg cocaine per day

Question 24

Temporal differences in illicit drug use also exist

Answer 24

o Recreational usage- weekend increases in concentration observed across EU for cocaine and MDMA in wastewater during the weekend (Friday to Monday)
o Amphetamine use was found to be distributed more evenly over the whole week

Question 25

What else can we find in wastewater? Population health

Answer 25

Question 26

Alcohol: A 20-city study

Answer 26

Question 27

Suspect screening: WBE to identify security threats?

Answer 27

Question 28

WBE and SARS-COV-2 dynamics

Answer 28

Picking up viruses in wastewater

Question 29

**Conclusions and future work **

Answer 29

• Wastewater based epidemiology is suitable for monitoring **near real-time trends **in chemical exposure and/or consumption behaviour
• Possible now to detect several chemicals at the ng/L in under 5 min, which enables** high spatiotemporal analysis** to be performed
• Analytical technologies now able to detect 1000s of chemicals qualitatively for early warning mechanisms (e.g., security threats to public safety)
• Linkage to health effects and outcomes needs much more detailed study (epidemiology) as well as better understanding of uncertainty
• Represent a new tangible and useful resource for a waste material