PBT classification under
EC 1107/2009: Practical
issues and a case example
of chlorpyrifos
POP
POP
PBT
Keith Solomon, John P. Giesy, Don
Mackay, Julie Anderson, Nick Poletika
May 14, 2014
SETAC EU
1
Criteria for POPs
Criteria for
Criteria for
Criteria for
persistence
bioaccumulation
toxicity (T)
(P)
(B)
Water: DT50 > BCF > 5,000 or Log No specific
60 d
KOW > 5
criteria other
Sediment:
Other, e.g., very
than
DT50 > 180 d toxic or
“significant
Soil: DT50 >
bioaccumulation in
adverse
180 d
nontarget species
effects”
2
Criteria for PBT (EC1107/2009)
Potential for
long-range
transport (LRT)
Air: DT50 > 2 d or
modeling or
monitoring data
which shows
long-range
transport
Persistence (P)
Marine water: t½ >60 d;
Fresh water t½ >40 d
Marine sediment: t½ >180 d
FW sediment: t½ >120 d
Soil: t½ >120 d
Bioaccumulation
(B)
BCF >2,000 in
aquatic species
Toxicity (T)
Chronic NOEC <
0.01 mg/L or is a
carcinogen,
mutagen, or toxic for
reproduction, or
other evidence of
toxicity
Off J Europ Commun 52:1-50.
The POPs Convention recommends that
decisions be made “after rigorous scientific
assessment”. Classification as a POP results
in global “ban”.
These criteria are more stringent than those for
POPs and, triggering two of these, results in being
placed on a list for substitution.
3
4
UNECE, 1996; UNEP, 2001, 2010
Application to a data-rich chemical
Cl
S
H 3C H 2C
O
H 3C H 2 C
O
P O
Cl
N
Cl
Chlorpyrifos has been proposed as a POP
(Watts, 2012).
Screening criteria under EC 1107/2009 do
not consider rich datasets available for
pesticides.
Many lines of evidence can be applied to
characterize pesticides as POPs and PBTs,
especially pesticides that have been on the
5
market for some time.
Plus 238 pages of SI
These papers were used as the basis for
physical and chemical properties as well6 as
toxicity, risk, and long-range transport.
1
Transformation, metabolism, and
degradation
Practical approach 1
Large amount of data, some old but also up-todate data.
We had access to unpublished data from Dow
AgroSciences, (any studies we needed).
Developed a scheme (similar to Klimisch et al
1997) to assess the strength of the studies on
persistence and bioaccumulation.
CPY, chlorpyrifos
Cl
S
H3C H2C O
P O
H3C H2C O
Cl
N
Cl
Cl
HO
H3C H2C O
Cl
S
P O
H3C H2C O
Cl
H3C H2C O
N
Cl
Desethyl chlorpyrifos
Cl
Cl
N
H3C O
Cl
Cl
Cl
CO2, N2,
TMP, trichloromethoxypyridine
Cl
N
Cl-
Used OECD guidelines as the ideal study, only
considered realistic concentrations, and realistic
environmental conditions. Excluded other studies.
Pyrolysis at 380°C
Cl
TCP, trichloropyridinol
N
P O
CPYO, chlorpyrifos-oxon Cl
HO
Cl
O
Cl
N
O
N
O
Cl
Used actual environmental conditions without
normalization as this is more realistic. Omitted
extreme conditions.
Cl
TCDD-Py
Low toxicity, de minimis risk
7
Effect of pH on rate of
hydrolysis
Practical approach 2
Studies in EU (1107/2009) were
separated from those in other regions.
Because of averaging in the environment,
mean or geometric mean values are
scientifically defensible, have been
recommended (SANCO draft guidance, 2012,
Solomon et al. 2013 Environ. Sci. Europ. 25), and
were used in the assessment.
Other lines of evidence were used as well.
1000
Half-life (d)
100
10
Omitted from
regression because
of unrealistic pH
1
8
0.1
0.01
0.001
1
10
pH
9
80
70
50
30
20
GM = 11
Percent rank
90
10
5
2
98
Data from EU soils
Data from non EU soils
95
90
80
70
50
30
GM = 73
Data from EU locations
Data for non-EU locations
GM = 2.2
95
Temp and pH
major drivers
Geomean
values do not
trigger the
criteria for
POPs or
PBTs
99
GM = 21
99
98
P: Half-life in soils (laboratory)
pH and conc.
of Cu++ the
main drivers
Geomean
values do
not trigger
the criteria
for POPs or
PBTs
Percent rank
P: Half-life in water
10
20
10
5
2
1
1
1
10
100
1
10
100
1000
Half-life in soils studied under laboratory conditions (d)
Half-life in water (d)
11
12
2
P: Half-life in soils, field
70
50
30
20
GM = 20
Percent rank
80
10
5
2
95
GM = 19
GM = 13
90
Data from EU locations
Data for non-EU locations
98
90
80
70
50
30
20
GM = 40
Data from EU locations
Data from non EU locations
95
10
5
2
1
1
1
1
Geomean
values do
not trigger
the criteria
for POPs or
PBTs
99
Percent rank
Temp and
pH major
drivers
Geomean
values do
not trigger
the criteria
for POPs or
PBTs
99
98
P: Half-life in sediments
10
100
10
1000
100
1000
Half-life in sediment (d)
Half-life in soil in the field (d)
13
B: BCF
POPs and long-range transport
50
GM = 853
30
20
10
5
2
1
0.1
1
10
100
1000
10000
BCF
No trophic magnification in plant-caribou-wolf food chain
in Canadian arctic (Morris et al., 2014 Environ Toxicol Chem in press
– early view)
15
Is chlorpyrifos a PBT (EC
1107/2009)
16
SSDs, NOAECeco, and monitoring
1.0
0.9
Does not trigger P and B.
The most sensitive chronic NOEC reported for
aquatic organisms of 0.005 µg/L and triggers the
T criteria for PBTs.
– Since CPY is an insecticide, this is expected.
– The key question is the relevance of this to exposures
in the general environment and the lack of significant
adverse effects from the ERAs for birds, pollinators,
and aquatic organisms (Cutler et al 2014; Giddings et al
2014; Moore et al 2014 Rev Environ Contam Toxicol 231).
0.8
USGS – 95th
centiles from
measured
concentrations
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
10 -3
17
Cosm NOAECeco
70
USGS, 0.056 pre-2001
80
Chlorpyrifos not a POP or a PBT on the basis of P
and B.
Measured half-life of chlorpyrifos in the atmosphere
does not exceed the trigger value of 2 d for LRT
(Mackay et al. 2014 Rev Environ Contam Toxicol 231).
Chlorpyrifos has been found in semi- and remotelocations, but;
Concentrations in air, rain and snow, aquatic and
terrestrial media, and biota are small and less than
the threshold of toxicity for terrestrial and aquatic
organisms.
USGS, 0.007 post-2001
90
Percent rank
Geomean
values do not
trigger the
criteria for
POPs or
BPTs
GM = 204
Fish
Invertebrates and plants
Omitted from regression (fish)
95
Proportion of species
99
98
14
10 -2
10 -1
10 0
10 1
10 2
10 3
Concentration of chlorpyrifos (μg L-1 )
10 4
18
Giddings et al 2014; Rev Environ Contam Toxicol 231
3
What about the oxon?
Chlorpyrifos oxon as a POP/PBT
CPY, chlorpyrifos
Cl
S
H3C
H2 C
O
H3C
H2 C
O
P
O
Cl
N
Cl
Cl
O
Less toxic
degradates
H3C
H2C
O
H3C
H2C
O
P
O
Cl
N
CPYO, chlorpyrifos-oxon C l
Chlorpyrifos oxon (CPYO) highly reactive does not
trigger the criteria for persistence in water, soil, or
sediment.
No data available for BCF, studies with ring-labelled
CPY provide equivalency for CPYO – does not
trigger B.
Toxicity for CPYO subsumed in that of CPY and it
also does not trigger “significant adverse effects”.
Modelled half-life in air (13 d – USEPA 2011) >2 d –
triggers LRT
– But….
19
S
H3 C H2C O
P O
H3 C H2C O
VOCs,
UVB
S
H3C H2C O
P O
H3C H2C O
Cl
Cl
•OH
Cl
N
Cl
•OH
20
H3C H2C O
H3C H2C O
O
P O
Cl
N
Oxon formed in the
atmosphere but partitions
strongly to water, smaller
KOW and greater solubility
Cl
Thank you
Cl
Cl
N
Cl
Oxon has short half-life in water (t½=5 d),
dissipates rapidly, POV is the key – no
significant accumulation in nearby or remote
locations
Oxon not found in surface waters in measurable
amounts (Williams et al., 2014 Rev Environ Contam Toxicol
231). Not a POP or a PBT.
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22
4