Micropollutants in European Rivers: A mode of action survey to support the development of effect-based tools for water monitoring

1. 2017.10.12 Lab Meeting 1
Literature review –
Micropollutants in European Rivers: A mode of action
survey to support the development of effect-based
tools for water monitoring
(ヨーロッパ河川中の微量汚染物質：
水質モニタリングにおけるeffect-based tools発展のための作用機序調査)
2017.10.12 (木)
Yamamoto-Nakajima Lab Meeting
Authors: Busch W., Schmidt S., Kuhne R., Schulze T., Krauss M., Altenburger A.
Year: 2016
Journal: Environ Toxicol Chem

2. 2017.10.12 Lab Meeting
Today's time schedule
2
Related research and my opinion (slide p. 13-15)
5 min
25 min
10 min
Research background (slide p.3-5)
Paper review and discussion (slide p.6-12 and the paper)
5 min Feedback

3. 2017.10.12 Lab Meeting
1. Background
Challenges in environmental risk assessments
3
Chemical pollution affects ecosystems as well as human health*.
High threat
Low threat
* Vörösmarty et al., 2010, Nature, 467: 555-561.

4. 2017.10.12 Lab Meeting
1. Background
Challenges in environmental risk assessments
4
 In water environments, hundreds to thousands of chemicals co-exist.
 Chemicals sometimes exhibit combined toxic effects (e.g., additive, synergistic).
⇒ Chemical analysis alone may underestimate (or overestimate) environmental risks.
Instrumental chemical analysis of target chemicals is
still the major approach in environmental monitoring of waters.
However....
Bioanalytical tools
can assess effects of a wide range of
chemicals and evaluate combined effects
⇒ have been recently introduced to water monitoring

5. 2017.10.12 Lab Meeting
2. Today’s purpose
What I want to do
5
Today I’d like to share information on
• the cutting-edge and future trends of water monitoring (in Europe)
• the potential of bioanalytical tools in water monitoring
• the challenges of bioanalytical tool application
I hope that you will
• understand overall concept
• give questions and comments

6. 2017.10.12 Lab Meeting
2. Today’s purpose
Paper
6
This paper is not directly related to my own research.
The reasons why I chose this paper are ...
• just interesting
• deal with a wide range of topics (because this is a kind of review paper)
• European monitoring systems are little different from USA (some members are familiar with USA’s style)

7. 2017.10.12 Lab Meeting
3. Paper review
Objective of the paper
7
To provide a better understanding of the capabilities and gaps of bioanalytical tools
Objective
What they did
I. Collect chemical monitoring data from different studies (Table 1, Fig.1, 2)
II. Estimate the potential risk of each detected chemical (Fig. 4, 5)
III. Search the modes of actions of all chemicals from databases (Fig. 8)
IV. Estimate the potential risk of each mode of action (Fig. 9)
⇒ Consider what kind of bioanalytical tools are needed in monitoring.
= effect-based tools

8. 2017.10.12 Lab Meeting
3. Paper review
II. Potential risk estimation
8
Basic knowledge
Biological response
(e.g., mortality)
Chemical concentrationEC50
50%
At ECx (Effective concentration x), x% of individuals in a test group are affected.
For example, half of individuals are affected at EC50.
ECs of many chemicals can be obtained from databases (e.g., ECOTOX)

9. 2017.10.12 Lab Meeting
3. Paper review
II. Potential risk estimation
9
What the authors did
• Collect EC5 of detected chemicals from ECOTOX databases
• If EC data is not available, the authors predicted EC based on the chemical property.
Van Leeuw et al., 1992, Environ Toxicol Chem 11: 267-282.
Lipophilic
親油性
Hydrophilic
親水性
QSAR (quantitative structure-activity relationship)
Predict (narcosis) toxicity of a chemical
based on the lipophilicity of the chemical
High toxicity
Low toxicity

10. 2017.10.12 Lab Meeting
3. Paper review
II. Potential risk estimation
10
What the authors did
• Based on EC5 values, the authors estimated HQ (hazard quotient) of each chemical.
HQ = MEC95* / EC5 (or predicted EC)
*MEC: measured environmental concentration
Higher HQs indicate higher potential risks.
95% of data 5% of data
MEC95
How to estimate MEC95

11. 2017.10.12 Lab Meeting
3. Paper review
IV. Risk of each mode of action (MoA)
11
HQs were summed up
per mode of action.
Example: MoA of adenosine receptor
・Clopidogrel
・Caffeine
EC5 for
fish
(mg/L)
MEC95
study#1
(mg/L)
MEC95
study#2
(mg/L)
…
HQ
study#1
HQ
study#2
…
Clopid
ogrel
0.071
(predicted)
Not
available
0.00004 …
Not
available
5.19×10-4 …
Caffein
e
720 0.00338
Not
available
… 4.70×10-6 Not
available
…
4.70×10-6 5.19×10-4Sum of HQ

12. 2017.10.12 Lab Meeting
3. Paper review
How do we utilize these results?
12
Based on the HQ of each mode of action,
we can determine the bioanalytical tools
suitable for water monitoring.
In this case,
Risks of angiotensin receptor blocker are high.
⇒ the corresponding in vitro assays* can be used.
*in vitro assay: Biological experiments in a test-tube.
ELISA Kit for Angiotensin Receptor
Once the bioanalytical tool is determined...

13. 2017.10.12 Lab Meeting
4. Related papers
Toxic contribution of detected chemicals
13
Once the bioanalytical tool is determined, the toxic contribution of each chemical can be evaluated.
Environmental sample
(e.g., wastewater)
Chemical A
EC50 100
µg/L
Measured concentration
Chemical A: 100 µg/L
Chemical B: 1 µg/L
・・・
500
µg/L
(EC50)
The toxic contribution (Toxic Unit) of chemical A to water sample:
𝑇𝑜𝑥𝑖𝑐 𝑈𝑛𝑖𝑡 =
100 [µ𝑔/𝐿] (𝑑𝑒𝑡𝑒𝑐𝑡𝑒𝑑 𝑐𝑜𝑛𝑐. )
500 [µ𝑔/𝐿] (𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑐𝑜𝑛𝑐. )
= 0.2
50%
If Toxic Unit of chemical A is 1, only chemical A can explain the toxicity of water sample.

14. 2017.10.12 Lab Meeting
4. Related papers
Actual example of chemical contribution estimation
14
Relatively good!
Biological effects were relatively explained by
measured chemicals.
Not good...
Biological effects were hardly explained by
measured chemicals.
Neale et al., 2017, Sci Total Environ 576: 785-795.

15. 2017.10.12 Lab Meeting
4. Related papers and my opinion
Summary and future perspective
15
 The authors ranked modes of actions in terms of hazardous quotients. Most of
modes of action had the same levels of hazardous quotients (Fig. 9).
→ Not only in vitro tests but also in vivo tests is still required? In vivo tests allows
us to expose whole organisms to contaminated samples, and responds to a
wide range of modes of action.
 It is still difficult to identify chemicals causing adverse effects (slide p.14).
→ 1. Need to improve mixture toxicity modelling
→ 2. Comprehensive chemical analysis
→ 3. Development of identification methods (e.g., EDA, TIE)

16. 2017.10.12 Lab Meeting
3. Paper review
Identification of causative agents by Effect-Directed Analysis (EDA)
16
Brack et al., 2003, Environ Sci Technol 37
Extract, F2~F4
F2.5.1~F2.5.10
F2.5.10
F2.5.8
15% of max
induction by
2,3,7,7-TCDD
F2
Extract
Once the bioanalytical tool is determined, chemicals causing adverse effects can be identified by EDA.
*EROD assay: ethoxyresorufin-O-deethylase assay. This can measure catalytic activity of cytochrome p4501A1.