Scientific opinion on "Draft environmental quality standards for priority substances under the Water Framework Directive" : nickel and its compounds.
Date: 2023-08-29
Institutions: Directorate-General for Health and Food Safety
Subjects: directive (EU), environmental monitoring, environmental standard, nickel, quality standard, research method, scientific report, toxic substance, water pollutant, water pollution

Scientific Committee on Health, Environmental and Emerging Risks 
SCHEER 

Scientific Opinion on "Draft Environmental Quality 
Standards for Priority Substances under the Water 
Framework Directive" 

Nickel and its compounds 

The SCHEER adopted this document 
during the plenary meeting on 22 December 2022  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Draft Environmental Quality Standards for Priority Substances Under the Water Framework Directive - nickel and its compounds 

Final Opinion  
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ACKNOWLEDGMENTS 

Members  of  the  Working  Group  are  acknowledged  for  their  valuable  contribution  to  this 
opinion. The members of the Working Group are: 

The SCHEER members: 
Marian Scott (Chair), Marco Vighi (Rapporteur), Thomas Backhaus, Teresa Borges, Raquel 
Duarte Davidson, Peter Hoet, Pim de Voogt, Rodica Ion 

The external experts: 
Andrew Johnson, Jan Linders  

All Declarations of Working Group members are available at the following webpage: 
Register of Commission expert groups and other similar entities (europa.eu) 

This  Opinion  has  been  subject  to  a  commenting  period  of  four  weeks  after  its  initial 
publication (from 12 October to 11 November 2022). Comments received during this period 
were considered by the SCHEER. For this Opinion, sections 7.2 and 7.3 were amended. 

Keywords:  
Metals, nickel, Water Framework Directive, environmental quality standards 

Opinion to be cited as: 
SCHEER  (Scientific  Committee  on  Health,  Environmental  and  Emerging  Risks),  Final 
Opinion on Draft Environmental Quality Standards for Priority Substances under the Water 
Framework Directive - nickel and its compounds, 22 December 2022  

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About the Scientific Committees (2022-2026) 
Two  independent  non-food  Scientific  Committees  provide  the  Commission  with  the 
scientific advice it needs when preparing policy and proposals relating to consumer safety, 
public health and the environment. The Committees also draw the Commission's attention 
to the new or emerging problems which may pose an actual or potential threat. 
These  committees  are  the  Scientific  Committee  on  Consumer  Safety  (SCCS)  and  the 
Scientific  Committee  on  Health,  Environmental  and  Emerging  Risks  (SCHEER).  The 
Scientific  Committees  review  and  evaluate  relevant  scientific  data  and  assess  potential 
risks.  Each  Committee  has  top  independent  scientists  from  all  over  the  world  who  are 
committed to working in the public interest. 
In  addition,  the  Commission  relies  upon  the  work  of  other  Union  bodies,  such  as  the 
European  Food  Safety  Authority  (EFSA),  the  European  Medicines  Agency  (EMA),  the 
European Centre for Disease prevention and Control (ECDC) and the European Chemicals 
Agency (ECHA). 

SCHEER 
This  Committee,  on  request  of  Commission  services,  provides  Opinions  on  questions 
concerning  health,  environmental  and  emerging  risks.  The  Committees  addresses 
questions on: 
- health and environmental risks related to pollutants in the environmental media and other
biological and physical factors in relation to air quality, water, waste and soils.
- complex  or  multidisciplinary  issues  requiring  a  comprehensive  assessment  of  risks  to
consumer safety or public health, for example antimicrobial resistance, nanotechnologies,
medical devices and physical hazards such as noise and electromagnetic fields.

SCHEER members 
Thomas Backhaus, Roberto Bertollini, Teresa Borges, Wim de Jong, Pim de Voogt, Raquel 
Duarte-Davidson,  Peter  Hoet,  Rodica  Mariana  Ion,  Renate  Kraetke,  Demosthenes 
Panagiotakos, Ana Proykova, Theo Samaras, Marian Scott, Emanuela Testai, Marco Vighi, 
Sergey Zacharov 

Contact 
European Commission 
DG Health and Food Safety 
Directorate B: Public Health, Cancer and Health security 
Unit B3: Health monitoring and cooperation, Health networks 
L-2920 Luxembourg
SANTE-SCHEER@ec.europa.eu

©European Union, 2023 

PDF   ISSN 2467-4559    ISBN 978-92-68-06268-5    doi:10.2875/948747    EW-CA-23-005-EN-N

The Opinions of the Scientific Committees present the views of the independent scientists 
who  are  members  of  the  committees.  They  do  not  necessarily  reflect  the  views  of  the 
European Commission. The Opinions are published by the European Commission in their 
original language only. 
SCHEER - Opinions (europa.eu)  

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ABSTRACT 

The dossier on Environmental Quality Standards for “Nickel” is reviewed by the SCHEER 
according to the general mandate on EQS dossiers.  

The proposed dossier is based on an EU RAR (2008) and a previous EQS dossier (2011) 
updated  by  inclusion  of  more  recent  data  and  according  with  the  2018  EQS  Technical 
Guidance.  

The probabilistic MAC-QSfw,eco= 8.2 μg L-1 is endorsed by the SCHEER. The same value 
is proposed for marine water. However, it is the opinion of the SCHEER that these values 
should be revised using BLMs for the bioavailability normalisation. 

The probabilistic AA-QSbioavailable, fw = 1.9 µg L-1 is endorsed by the SCHEER. 

The  probabilistic  AA-QS  sw,eco  =  3.1  µg  L-1  is  endorsed  by  the  SCHEER  in  absence  of 
suitable BLMs for the marine environment. 

The probabilistic QS fw, sed = 22 mg kgdw
proposed for marine water. 

-1 is endorsed by the SCHEER. The same value is 

For secondary poisoning, the QSbiota, secpois, fw = 8.9 mg kg-1
ww for fish and 2.6 mg kg-
1
ww  for  bivalves  are  endorsed  by  the  SCHEER.  However,  the  SCHEER  notes  several 
mistakes in the text of the dossier. 

The QSbiota, hh food =1.6 mg kgbiota
water is not performed due to uncertainties on the definition of BAF. 

-1 is endorsed by the SCHEER. The back calculation to 

The existing European drinking water standard of 20 µg L-1 is endorsed by the SCHEER. 

The most critical EQS has been identified as the AA-QSbioavailable, fw = 1.9 µg L-1. 

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TABLE OF CONTENTS 

ACKNOWLEDGMENTS ............................................................................................. 2 

ABSTRACT ............................................................................................................ 4 

1. 

2. 

3. 

BACKGROUND .............................................................................................. 6 

TERMS OF REFERENCE ................................................................................... 6 

OPINION ...................................................................................................... 7 

Section 7. Effects and quality standards ................................................................... 7 

Section 7.1. Acute aquatic ecotoxicity ...................................................................... 8 

Section 7.2. Chronic aquatic ecotoxicity ................................................................... 8 

Section 7.3.  Sediment ecotoxicology ....................................................................... 9 

Section 7.4. Secondary Poisoning ...........................................................................11 

Section 7.5. Human health ....................................................................................11 

4. 

5. 

6. 

7. 

CRITICAL EQS ............................................................................................. 12 

SCHEER RESPONSES TO ADDITIONAL QUESTIONS PUT BY THE COMMISSION ..... 12 

LIST OF ABBREVIATIONS .............................................................................. 14 

REFERENCES ............................................................................................... 14 

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1. BACKGROUND 

Article 16 of the Water Framework Directive (WFD, 2000/60/EC) requires the Commission 
to identify Priority Substances among those presenting significant risk to or via the aquatic 
environment, and to set EU Environmental Quality Standards (EQS) for those substances 
in water, sediment and/or biota. In 2001, a first list of 33 Priority Substances was adopted 
(Decision  2455/2001)  and  in  2008,  the  EQS  for  those  substances  were  established 
(Directive 2008/105/EC or EQS Directive, EQSD). WFD Article 16 requires the Commission 
to  periodically  review  the  list.  The  first  review  led  to  a  Commission  proposal  in  2011, 
resulting  in  the  adoption  of  a  revised  list  in  2013  containing  an  additional  12  Priority 
Substances. Technical work to support a second review has been underway for some time, 
and several substances have been identified as possible candidate Priority Substances. The 
Commission  will  be  drafting  a  legislative  proposal,  with  the  aim  of  presenting  it  to  the 
Council and the Parliament sometime around mid-2022. 

The technical work has been supported by the Working Group (WG) Chemicals under the 
Common  Implementation  Strategy  for  the  WFD.  The  WG  is  chaired  by  DG  Environment 
and  consists  of  experts  from  Member  States,  EFTA  countries,  candidate  countries  and 
several European umbrella organisations representing a wide range of interests (industry, 
agriculture, water, environment, etc.).  

Experts nominated by WG Members (operating as individual substance Expert Groups and 
through the Sub-Group on Review of Priority Substances, SG-R) have been deriving EQS 
for the possible candidate substances and have produced draft EQS for most of them. In 
some cases, a consensus has been reached, but in others there is disagreement about one 
or  other  component  of  the  draft  dossier.  The  EQS  for  a  number  of  existing  priority 
substances are currently also being revised.  

The  EQS  derivation  has  been  carried  out  in  accordance  with  the  Technical  Guidance 
Document on Deriving EQS (TGD-EQS) reviewed by the SCHEER1. 

2. TERMS OF REFERENCE  

DG Environment now seeks the opinion of the SCHEER on the draft EQS for the proposed 
Priority Substances and the revised EQS for a number of existing Priority Substances. The 
SCHEER is asked to provide an Opinion for each substance. We ask that the SCHEER focus 
on: 

Generic questions to the SCHEER 

o  Have  the  EQS  been  correctly  and  appropriately  derived,  in  the  light  of  the 

available information and the TGD-EQS? 

o  Has  the  most  critical  EQS  (in  terms  of  impact  on  environment/health)  been 

correctly identified? 

Additional questions to the SCHEER 

Additional questions to  the SCHEER can be found in the file  “Environmental Quality 
Standards Dossier ‘Nickel’ for the Scientific Committee on Health, Environmental and 
Emerging Risks (SCHEER)”, otherwise they are listed below: 

1  https://circabc.europa.eu/ui/group/9ab5926d-bed4-4322-9aa7-9964bbe8312d/library/ba6810cd-e611-4f72-
9902-f0d8867a2a6b/details  

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o  Does SCHEER agree with the assessment factor selected of 5 for the proposed MAC-

QSeco using the probabilistic approach? 

o  Does  SCHEER  agree  with  the  assessment  factor  selected  of  2  for  the  proposed 

bioavailable-AA-QSfw,eco ? 

o  What  is  SCHEER  Committee’s  opinion  on  the  field  and  micro/mesocosm  studies 

available on Nickel draft dossier? 

o  Does  SCHEER  agree  with  the  assessment  factor  selected  of  3  for  the  proposed 

bioavailable-AA-QS freshwater, sediments? 

o  Does SCHEER agree with the proposed bioavailable-AA-QSmw,sed? 

o  What is SCHEER Committee’s opinion on the bioaccumulation factor used in the QS 

secondary poisoning derivation? 

The SCHEER responds to these questions at the end of the Opinion. 

3. OPINION 

It should be noted that in a separate synthesis Opinion, the SCHEER provides an analysis 
of weaknesses and unresolved issues common to all dossiers.  This includes a discussion 
of the risk assessment  method and  of SCHEER’s concern  regarding the completeness  of 
the data used for the estimation of the different QS values.   

In the final version of the dossier on Nickel (July 2022), the previous relevant documents, 
which represent the basis for the present document, are listed: 

•  The  European  Union  Risk  Assessment  Report  (EU  RAR)  approved  in  May  2008  (EC, 
2008);  the  RAR  was  evaluated  by  the  Scientific  Committee  on  Health  and 
Environmental Risks (SCHER 2009) that judged it as a  very high-quality report and 
endorsed almost all conclusions, with some suggestions for further improvement (e.g., 
improving the sections on the sediment compartment, and on risk for soil organisms). 
•  The EQS draft dossier of 2011, proposing AA-QSfw, bioavailability of 2 µg/L, AA-QSsw of 8.6 
µg/L and MAC-QS of 34 µg/L. The dossier was also reviewed by the SCHER (SCHER, 
2011) that endorsed the proposed QS, highlighting the need for update in function of 
new information (e.g., higher tier data). 

•  The  EQS  draft  dossier  of  2017,  considering  recent  information,  including  higher  tier 

data. 

The present version has been updated by including recent data (from 2017 to 2021) and 
according to the last version of the EQS Technical Guidance 2018 (EC, 2018). 

Specific comments on the different sections of the dossier are listed below. 

Section 7. Effects and quality standards 

The SCHEER agrees with the procedures for the collection and selection of data. 

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Section 7.1. Acute aquatic ecotoxicity 

Extensive  datasets  are  provided  for  freshwater  (102  species)  and  marine  (35  species) 
acute  toxicity  data.  There  was  no  statistically  significant  difference  between  the  acute 
sensitivities of freshwater and marine organisms. Therefore, in accordance with the EQS 
TGD (EC, 2018), the two datasets were combined. The SCHEER agrees with the procedure.  

Although biotic ligand models (BLMs) for Ni exist and were used in previous reports (e.g., 
EU RAR, 2008), the dossier states that “User-friendly acute NiBLM models for freshwater 
and saltwater are not available”. Therefore, the MAC-QSs have been derived on the basis 
of the dissolved metal, not normalised on the bioavailable fraction.  

It is the opinion of the SCHEER that the  proposed QS should be considered preliminary, 
limited to dissolved Ni. Existing BLMs should be considered, to produce bioavailable QS, 
whenever  possible.  This  is  also  strongly  recommended  by  the  EQS  Technical  Guidance 
2018 (EC, 2018). 

A deterministic MAC-QSfw,eco is based on the lowest acute effect value available, the 96h-
EC50=14  µg  L-1  for  larval  development  of  the  echinoderm  Evechinus  chloroticus. 
Considering the large dataset available, an AF of 10 is applied leading to a MAC-QSfw,eco 
= 1.4 μg L-1. The SCHEER agrees with the proposed deterministic QS. 

The  large  dataset  is  suitable  for  the  application  of  the  probabilistic  approach.  The  SSD 
curve provides an HC5= 41 µg L-1. By applying an AF of 10, according to the TGD, a MAC-
QSfw,eco  =  4.1  μg  L-1  is  obtained.  However,  considering  the  large  dataset  (135  species 
covering 12 major taxonomic groups), an AF of 5 is suggested, leading to a MAC-QSfw,eco 
= 8.2 μg L-1. The SCHEER agrees with the proposed probabilistic QS. 

For the marine environment, considering that the standard deviation of the log transformed 
L(E)C50  values  is  >  0.5,  an  AF  of  100  is  applied  to  the  96h-EC50=  14  µg  L-1  on  the 
echinoderm Evechinus chloroticus, according to the TGD, leading to a MAC-QSsw,eco= 0. 14 
μg L-1. However, according to the TGD, an AF of 10 may be applied if representative species 
for the most sensitive taxonomic group are included in the data set. Considering that the 
dataset includes 12 taxonomic groups, it is the opinion of the SCHEER that an AF of 10 is 
more appropriate. Therefore, the SCHEER proposes a deterministic MAC-QSsw,eco =1.4 μg 
L-1, same as for freshwater. The SCHEER also noted that a value of 0.14 μg L-1 is close to 
the natural background concentrations. 

For  the  probabilistic  approach,  the  same  procedure  applied  for  freshwater  is  proposed, 
leading to a MAC-QSsw,eco =8.2 μg L-1. The SCHEER agrees with the proposed probabilistic 
QS. 

Since  the  probabilistic  procedure  should  be  preferred  to  the  deterministic  one  if  it  is 
sufficiently reliable and statistically sound, it is the opinion of the SCHEER that the final 
MAC-QS =8.2 μg L-1 should be proposed for both fresh and marine waters. 

Section 7.2. Chronic aquatic ecotoxicity 

Freshwater  and  marine  water  chronic  ecotoxicity  datasets  have  been  kept  separate 
because, according to the TGD (EC, 2018), pooling of freshwater and saltwater data should 
be avoided when availability corrections have been applied. The SCHEER agrees with this 
procedure, considering that, for freshwater chronic data, BLM has been applied. 

For freshwater, the dataset from the EU RAR (EC, 2008) (214 endpoints, 31 species and 9 
major  taxonomic  groups)  was  implemented  with  data  from  the  2011  dossier  and 
additionally  with  more  recent  data.  All  data  were  normalised  using  suitable  BLMs.  The 
SCHEER  is  aware  that  the  BLM  approach  may  be  updated  and  improved,  covering  the 
variability  of  European  water  chemistry  conditions.  Therefore,  the  SCHEER  recommends 

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that, for further revisions of the metal dossiers, the most recent updates of the BLM would 
be applied.  

Microcosm and field studies are also available and were taken into account in the discussion 
of the selection of the AF. 

By applying a probabilistic approach to the bulk of data, an HC5 of 3.7 μg L-1 is calculated. 
In the dossier the value is rounded, but the SCHEER is of the opinion that this is not correct. 

According to the TGD, an AF from 1 to 5 may be applied to the HC5. Considering the large 
dataset  available  together  with  some  residual  uncertainties,  an  AF  of  2  is  proposed, 
resulting  in  a  probabilistic  AA-QSbioavailable,  fw  =  2  µg  L-1.  The  SCHEER  agrees  with  the 
procedure; however, it suggests a not-rounded value of 1.9 µg L-1. Therefore, the value of 
1.9 µg L-1 for the AA-QSbioavailable, fw is endorsed by the SCHEER.  

A deterministic AA-QS is not proposed in the dossier for freshwater. It is the opinion of the 
SCHEER that the reason for that should be justified. 

For the marine water too, a large dataset is available by combining the EU RAR dataset 
with more recent data (30 species and 8 major taxonomic groups). Due to the lack of a 
reliable  BLM  for  marine  water,  data  are  not  normalised  for  bioavailability.  The  SCHEER 
agrees with the approach. 

The deterministic approach is applied to the lowest chronic value (80h-EC10 of 5.5 μg L-1 
for the crustacean Acartia sinjiensis). An AF of 10 is applied, resulting in a deterministic 
AA-QS sw = 0.55 µg L-1. The deterministic QS is endorsed by the SCHEER. 

By applying a probabilistic approach to the bulk of data, an HC5 of 9.2 μg L-1 is obtained.  

According to the TGD, an AF from 1 to 5 may be applied to the HC5. Considering the large 
dataset  available  together  with  some  residual  uncertainties,  an  AF  of  3  is  proposed, 
resulting in a probabilistic AA-QS sw,eco = 3.06 µg L-1 (rounded to 3.1 µg L-1). The SCHEER 
agrees with the procedure and endorses the AA-QS sw,eco.  

Since  the  probabilistic  procedure  should  be  preferred  to  the  deterministic  one  if  it  is 
sufficiently reliable and statistically sound, it is the opinion of the SCHEER that the final 
AA-QS sw,eco = 3.1 µg L-1 should be proposed for marine waters. 

Section 7.3.  Sediment ecotoxicology  

Sediment toxicity of metals is strongly affected by the availability patterns of metals in this 
compartment. Due to the lack of information on these patterns, sediment toxicity was not 
adequately addressed in the 2008 EU RAR.  

There is evidence in the literature that sediment acid volatile sulphide (AVS) concentration 
is a key parameter affecting metal availability (Di Toro et al. 1990, 1992; Schlekat et al. 
2016).  

In  the  dossier,  normalisation  of  available  data  is  performed  using  the  equation  below 
(Vangheluwe et al. 2013): 

𝐸𝐶20𝑅𝑊𝐶 =   𝐸𝐶20𝑡𝑒𝑠𝑡  [

𝐴𝐹𝑅𝑊𝐶
𝐴𝐹𝑡𝑒𝑠𝑡

] ^𝑠𝑙𝑜𝑝𝑒 

Where  RWC  is  a  reasonable  worst-case  scenario  for  sediment  characteristics,  AF  is  the 
abiotic factor (e.g., AVS) affecting availability, and the slope is those of the concentration-
toxicity curve.   

It is the opinion of the SCHEER that the normalisation procedure is suitable.  

The normalisation was applied to sediment toxicity data for which sediment data suitable 

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for the application of the equation were available. This led to a dataset of 8 species and 4 
major taxonomic groups. 

The  deterministic  approach  is  applied  to  the  lowest  normalised  value  (EC10  of  75.9  mg 
 -1 for biomass to Hyalella azteca). An AF of 10 is applied, resulting in a deterministic 
kgdw
QS fw, sed = 7.6 mg kgdw

-1. The deterministic QS is endorsed by the SCHEER. 

The probabilistic approach, based the available data set, gives a bioavailability-based HC5 
-1. An AF is not proposed in the dossier, considering some uncertainties 
of 108.17 mg kgdw
and disagreements in the discussion among stakeholders and experts of different MS, also 
considering  that  no  clear  indications  are  reported  in  the  TGD  about  the  AF  selection  for 
SSDs based on sediment toxicity data. Therefore, a specific question on that issue is asked 
to the SCHEER. 

It must be noted that the general requirements for SSD indicated in the TGD (at least 10 
NOECs/EC10s values, from different species covering at least 8 taxonomic groups) are not 
met. However, for sediments, these requirements are difficult to meet, due to the absence 
of several important taxonomic groups. Therefore, an SSD developed on 8 species and 4 
taxonomic groups may be assumed as acceptable for sediments. The SCHEER agrees with 
this approach. 

By applying an AF of 5, a QS sed = 22 mg kgdw

-1 is obtained.  

In the dossier it is mentioned that some MS experts observed that, by applying an AF of 5 
the  resulting  QS  sed  would  be  higher  than  many  ambient  concentrations  in  Europe  (see 
section 6 of the dossier). Therefore, an AF of 3 or 1 is proposed, leading to QS sed of 36 or 
108 mg kgdw

-1 respectively. 

The SCHEER notes that, although the SSD for sediment may be considered as acceptable, 
the database used has substantial uncertainty. In any case, even applying an AF of 5, the 
resulting  QS  is  about  three  times  higher  than  those  obtained  using  the  deterministic 
procedure.  

Moreover,  looking  at  the  minimum-maximum  range  of  Ni  concentrations  in  European 
-1  is  lower  than  the 
sediments  (table  at  page  11  of  the  dossier),  the  QS  of  22  mg  kgdw
maximum values reported but is about one order of magnitude higher than the minimum 
values  reported.  On  the  other  hand,  even  the  AA-QSfw  is  lower  than  some  measured 
concentrations in Europe. 

The SCHEER is aware that the behaviour of metals in the environment, and in particular in 
chemically  complex  matrix  like  sediments,  is  a  difficult  issue  requiring  an  in-depth 
knowledge of sediment characteristics which is rarely available. This led, in many cases, 
to the need for precautionary approaches. 

Therefore, it is the opinion of the SCHEER that an AF of 5 is suitable, leading to a QS fw, sed 
= 22 mg kgdw

-1. 

Since  the  probabilistic  procedure  should  be  preferred  to  the  deterministic  one  if  it  is 
sufficiently reliable and statistically sound, it is the opinion of the SCHEER that the final QS 
fw, sed = 22 mg kgdw

-1 should be proposed. 

For  marine  sediment  data,  normalisation  for  availability  is  not  possible,  therefore,  data 
cannot be merged with freshwater data. 

The deterministic approach is used by applying an AF of 10 to the 15d NOEC on Amphiascus 
-1. It is the opinion of the 
-1, leading to a QSsw, sed =6.8 mg kgdw
teniuremis of 68 mg kgdw
SCHEER that the deterministic approach is properly applied. Hence, the QSfw,sed  should be 
used  for  both  the  marine  and  freshwater  compartments.  The  SCHEER  agrees  with  this 
observation. Therefore, a QS sw, sed = 22 mg kgdw

-1 is proposed.  

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Section 7.4. Secondary Poisoning 

The procedure used in the 2011 dossier is firstly reported but not used for deriving QS. 
The  reason  for  reporting  this  procedure  is  unclear.  Then,  the  QSbiota,  secpois  derivation  in 
2022 is described. 

Two different toxicity values are considered and compared in the dossier: 

•  a NOAEL of 1.1 mg.kg-1

bw.d-1 for a 2-generation reproductive study on rat 

(exposed through gavage); 

•  a NOEC of 200 mg kgww

-1 in food for a 90-d test on mallard (Anas platyrhynchos). 

The NOEC on mallard is a concentration in food and is erroneously reported as mg.kg-1
and as mg.kg-1

bw.d-1 in the tables on pages 42 and 47 respectively. 

bw 

The NOAEL of 1.1 mg.kg-1
bw.d-1 has water as vehicle. The dossier assumes that the mass 
fraction of Ni dose absorbed from the gastrointestinal tract is 27% for drinking water and 
bw.d-
0.7% for food.  Therefore, the absorbed Ni dose in the rat experiment is 0.297 mg.kg-1
bw.d-
1. To absorb the same dose through food the total dietary dose would be 42.4 mg.kg-1
1.  

According  to  the  EQS  Technical  Guidance  (EC,  2018),  the  method  of  energy-normalised 
-1d-1  is 
diet  concentrations  is  applied.  The  calculation,  using  a  NOAEL  of  42.2  mg  kgbw
reported in detail and is properly performed, leading to a Cenergy normalised of 32.30 µg kJ-1.  

-1.and using 
Another calculation is made starting from the NOEC for mallard of 200 mg kgww
the “method B” of the technical guidance, to be applied to concentrations in the diet. In 
this case, the calculation (not reported in detail) leads to a Cenergy normalised of 16.13 µg kJ -1. 
It is the opinion of the  SCHEER that the value  is correct. Being lower  than the previous 
one, this value was used for further calculations. 

Then, the Cfood item is calculated, according to the Technical Guidance, using the following 
equation: 

Cfood  item  [mg/kgww]  =  Cenergy  normalised  [mg/kJ]  *  energy  contentfood  item,  dw  *  (1-moisture 
fractionfood item) = Cenergy normalised [mg/kJ] * energy contentfood item, fw     

The energy contents and the moisture fractions used were 21 kJ/gdw and 73.7% for fish, 
and 19.3 kJ/gdw and 91.7% for bivalves, respectively. The energy contents in the dossier 
are erroneously indicated as kJ/gfw.  

The obtained Cfood item were 89.09 mg/kgww for fish and 25.83 mg/kgww for bivalves. It is 
the opinion of the SCHEER that the calculation is correct. However, many errors in the text 
make the dossier confused and difficult to follow. 

An AF of 10 was applied to the Cfood item, obtaining a QSbiota, secpois, fw = 8.9 mg kg-1
fish and 2.6 mg kg-1
the SCHEER notes several mistakes in the text of the dossier. 

ww for 
ww for bivalves. The QSs are endorsed by the SCHEER. However,  

Considering that nickel does not biomagnify, the QSbiota, secpois assessment for marine waters 
has been omitted. The SCHEER agrees with this decision. 

Considering several uncertainties associated with BAF values, no back-calculation to water 
is proposed in the dossier. The SCHEER agrees with this decision. 

Section 7.5. Human health 

For  the  protection  of  human  health  risk  via  consumption  of  fishery  products,  after 
describing the procedures used in the 2008 EU RAR and in the 2011 dossier, the QSbiota, 
secpois is derived according to the procedure described in the EQS Technical Guidance (EC, 
2018), based on the following equation: 
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Where: 

QSbiota hh food = 0.2 TLhh / 0.00163 

•  QSbiota hh,food = Quality standard for human health via consumption of fishery 

products (mg kg-1

biota) 

•  0.2 = default fraction of TLhh allocated to fishery products consumption  
•  TLhh = threshold limit from mammalian studies (ADI or TDI) (mg kg-1
•  0.00163 (kgfish kgbw

-1d-1) = estimated daily fishery products consumption (default 

bw d-1) 

0.115 kg d-1) per kg body weight (default 70 kg). 

Using a TDI of 13 µgkgbw
(rounded to QSbiota, hh food =1.6 mg kgbiota

-1) is obtained. 

-1 proposed by EFSA (2020), a QSbiota, hh food =1595.09 µg kgbiota

-1 

The QS is endorsed by the SCHEER. 

Due to uncertainties about the definition of BAF for Ni, the back calculation to water is not 
proposed in the dossier. The SCHEER agrees with this decision. 

For  the  protection  of  human  health  risk  via  consumption  of  drinking  water,  the  existing 
European drinking water standard of 20 µg L-1 is proposed. The SCHEER agrees with 
this decision. 

4. CRITICAL EQS 

In light of the data provided in the dossier, the most critical EQS (in terms of impact on 
environment/health) has been identified as the AA-QSbioavailable, fw = 1.9 µg L-1. It must 
be considered that this value is expressed as bioavailable concentration in water.  

5. SCHEER RESPONSES TO ADDITIONAL QUESTIONS PUT BY THE COMMISSION 

Does  SCHEER  agree  with  the  assessment  factor  selected  of  5  for  the  proposed 
MAC-QSeco using the probabilistic approach? 

As already clarified in the text of the Opinion, the SCHEER agrees with the selected AF of 
5. 

Does  SCHEER  agree  with  the  assessment  factor  selected  of  2  for  the  proposed 
bioavailable-AA-QSfw,eco ? 

The extension of the dataset could suggest a lower AF. However, considering some residual 
uncertainties, the SCHEER agrees with the selected AF of 2. 

What is SCHEER Committee’s opinion on the field and micro/mesocosm studies 
available on Nickel draft dossier? 

Micro/mesocosm  and  field  studies  are  always  characterised  by  high  variability  and 
uncertainty. Therefore,  they must be  evaluated with care.  However, they are  extremely 
useful for evaluating if QS, derived from laboratory studies, may be really protective for 
complex biological communities. In the case of higher tier studies available on nickel,  in 
spite  of some uncertainties, they support the hypothesis that an AF of 1  on the  chronic 
HC5 is not protective enough and an AF of 2 is necessary. 

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Does  SCHEER  agree  with  the  assessment  factor  selected  of  3  for  the  proposed 
bioavailable-AA-QS freshwater, sediments? 

It  is  the  opinion  of  the  SCHEER  that,  considering  the  uncertainties  deriving  from  the 
reduced dataset used for the SSD curve on sediments, an AF of 5 is more adequate. More 
details supporting this preference are reported in the text of the Opinion. 

Does SCHEER agree with the proposed bioavailable-AA-QSsw,sed? 

The SCHEER agrees that no evidence exists to suggest different sensitivity between marine 
and freshwater sediment organisms. Moreover, for freshwater, a  QS  calculated  with the 
probabilistic procedure is accepte, that is substantially higher from those calculated with 
the deterministic one.  

Therefore, the SCHEER agrees with the proposal of the stakeholder experts  of using the 
same QS for fresh and marine water.  However, it must be those calculated with an AF of 
-1), and not those proposed by the stakeholder experts calculated with 
5 (i.e., 22 mg kgdw
an AF of 1 (i.e., 109 mg kgdw

-1). 

What is SCHEER Committee’s opinion on the bioaccumulation factor used in the 
QS secondary poisoning derivation? 

Considering  several  uncertainties  associated  with  BAF  values  of  nickel,  and  particularly 
considering  that,  in  the  case  of  metals,  bioaccumulation  and  bioconcentration  may  be 
variable  with  concentration,  in  the  dossier  BAF  is  not  used  for  back  calculation  for 
secondary poisoning, as well as for human health. The SCHEER agrees with this decision. 

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6. LIST OF ABBREVIATIONS

AA-QS 
ADI 
AF 
AMR 
BAF 
BCF 
BMF 
EC50 
EQS 
HC5 
MAC-QS 
MIC 
NOAEL 
SSD 

Annual Average Quality Standard 
Acceptable Daily Intake 
Application Factor  
Anti-Microbial Resistance 
Bioaccumulation Factor 
Bioconcentration Factor 
Biomagnification Factor 
Effective Concentration 50% 
Environmental Quality Standards  
Hazardous Concentration 5% 
Maximum Acceptable Concentration Quality Standard 
Minimum Inhibitory Concentration 
No Observed Adverse Effect Level 
Species Sensitivity Distribution 

7. REFERENCES

EUROPEAN COMMISSION (EC). 2008. European Union  risk assessment report  on nickel, 
nickel  sulphate, nickel  carbonate, nickel chloride, nickel  dinitrate, Denmark, Final report 
May  2008.  Prepared  by  Denmark,  Danish  Environmental  Protection  Agency  on  behalf  of 
the European Union. 

EUROPEAN  COMMISSION  (EC).  2018.  Technical  Guidance  for  Deriving  Environmental 
Quality Standards. Guidance Document No. 27, Updated version 2018. Document endorsed 
by EU Water Directors at their meeting in Sofia on 11-12 June 2018. 

SCHER. 2008. Scientific opinion on the risk assessment report on nickel, nickel carbonate, 
nickel chloride, nickel dinitrate, nickel sulphate; indirect exposures part, CAS 7440-02-0; 
3333-67-3; 7718-54-9; 13138-45-9; 7786-81-4, 15 July 2008. 

SCHER. 2011. Scientific Committee on Health and Environmental Risks (SCHER) Opinion 
on  “Chemicals  and  the  Water  Framework  Directive:  Draft  Environmental  Quality 
Standards”  Nickel.  Health  &  Consumer  Protection,  Directorate-  General,  European 
Commission. 25 May 2011 

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