Models for Calculating Predicted Environmental Concentrations (PEC) of Pesticides in Surface Waters: Review, Selection Criteria, and Recommendations for Regulatory Applications

	FOCUS Step 1–2 v.3.2	FOCUS Step 3	EXPRESS v.3.2	GERDA v.3.2	PWC v. 2.001	EUSES v. 2.2.0	SWCC v. 1.106	EXPOSIT v. 3.02	EVA v. 3 (rev 2h)	MUST v. 1.0	EPIC v. 5.0	PEC CKB	Simple PEC
Molar mass	yes	yes	yes	yes	yes	yes	yes	no	no	yes	yes	no	no
Water solubility	yes	yes	yes	yes	yes	yes	yes	yes	yes	no	no	no	no
Vapour pressure	no	yes	yes	yes	yes	yes	yes	no	yes	no	no	no	no
DT50soil	yes	yes	yes	yes	yes	yes	yes	yes	no	yes, but not possible to edit	no	no	no
Koc/Kom	yes	yes	yes	yes	yes	yes	yes	yes	no	yes, but not possible to edit	no	yes	no
DT50sediment/water	yes	yes	yes	yes	yes	yes	yes	no	yes	yes, but not possible to edit	no	no	no
Freundlich exponent 1/n	no	yes	no	yes	no	no	no	no	no	no	no	no	no
Plant uptake factor	no	yes	no	yes	no	no	no	no	no	no	no	no	no
Crop type	yes	yes	yes	yes	yes	no	yes	no	yes	no	yes	no	yes
Dose	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	no	yes	yes
Application dates	season - Mar–May, Jun–Sept, Oct–Feb	yes	yes	yes	yes	no	yes	yes	no	no	no	no	no
Interval	yes	yes	yes	yes	yes	no	yes	yes	yes	no	no	no	no
Application method	yes	yes	yes	yes	yes	no	yes	no	no	no	yes	no	no

Table 2.

Comparison of parameters needed in FOCUS Step 1 and Step 2

Parameter	Step 1	Step 2
Applied rate	●	●
Number of application	●	●
Crop type	●	●
Region and season of application		●
Crop interception		●
Koc/Kom	●	●
DT50 whole system	●
DT50 water		●
DT50 sediment		●
DT50 soil		●

Model operation scheme for FOCUS Step 1. All entries occur on the same day

Model operation scheme for FOCUS Step 2. Loadings based on sequential application patterns

Table 3.

Basic drift values in the authorisation procedure for plant protection products [Candolfi et al. 2001]

Distance [m]	Field crops	Fruit crops		Grapevine		Hops	Vegetables/Ornamentals/Small fruit
Distance [m]	Field crops	early	late	early	late	Hops	<50 cm	≥50 cm
Basic drift values for one application Ground sediment in % of the application rate (90th percentiles)
1	2,77					19,33	2,77
3	0,95	29,20	15,73	2,70	8,02	19,33	0,95	8,02
5	0,57	19,89	8,41	1,18	3,62	11,77	0,57	3,62
10	0,29	11,81	3,60	0,39	1,23	5,77	0,29	1,23
15	0,20	5,55	1,81	0,20	0,65	3,84	0,20	0,65
20	0,15	2,77	1,07	0,13	0,42	2,49	0,15	0,42
30	0,10	1,04	0,54	0,07	0,22	0,56	0,10	0,22
40	0,07	0,52	0,32	0,04	0,14	0,25	0,07	0,14
50	0,06	0,36	0,24	0,03	0,09	0,15	0,06	0,09
75	0,04	0,20	0,11	0,015	0,05	0,04	0,04	0,05
100	0,03	0,30	0,06	0,007	0,033	0,02	0,03	0,033
125	0,025	0,03	0,04	0,007	0,024	0,01	0,025	0,024
150	0,021	0,021	0,03	0,005	0,018	0,004	0,021	0,018
175	0,018	0,018	0,024	0,004	0,013	0,004	0,018	0,013
200	0,016	0,016	0,019	0,003	0,011	0,003	0,016	0,011
225	0,014	0,008	0,016	0,003	0,008	0,002	0,014	0,008
250	0,012	0,006	0,013	0,002	0,008	0,001	0,012	0,008
Basic drift values for two applications Ground sediment in % of the application rate (82nd percentiles)
1	2,38					17,73	2,38
3	0,79	25,53	12,13	2,53	7,23	17,73	0,79	7,23
5	0,47	16,87	6,81	1,09	3,22	9,60	0,47	3,22
10	0,24	9,61	3,11	0,35	1,07	4,18	0,24	1,07
15	0,16	5,61	1,58	0,18	0,56	2,57	0,16	0,56
20	0,12	2,59	0,90	0,11	0,31	1,21	0,12	0,31
30	0,08	0,87	0,40	0,06	0,19	0,38	0,08	0,19
40	0,06	0,40	0,23	0,03	0,12	0,19	0,06	0,12
50	0,05	0,22	0,15	0,02	0,08	0,09	0,05	0,08
75	0,03	0,07	0,07	0,01	0,04	0,03	0,03	0,04
100	0,023	0,04	0,04	0,008	0,03	0,02	0,023	0,03
125	0,019	0,02	0,024	0,005	0,02	0,007	0,019	0,02
150	0,015	0,01	0,018	0,004	0,015	0,005	0,015	0,015
175	0,013	0,01	0,013	0,003	0,011	0,004	0,013	0,011
200	0,012	0,005	0,011	0,003	0,009	0,003	0,012	0,009
225	0,010	0,004	0,008	0,002	0,007	0,002	0,010	0,007
250	0,009	0,003	0,006	0,002	0,007	0,001	0,009	0,007

Area (land+rivers) of regional system	0.1	[km²]	S
Area fraction of freshwater, region (excl. sea)	1E-03	[−]	S
Area fraction of natural soil, region (excl. sea)	0.01	[−]	S
Area fraction of agricultural soil, region (excl. sea)	0.979	[−]	S
Area fraction of industrial/urban soil, region (excl. sea)	0.01	[−]	S
Length of regional seawater	1E-06	[km]	S
Width of regional seawater	1E-06	[km]	S
Area of regional seawater	1E-06	[km²]	S
Area (land+rivers+sea) of regional system	0.1	[km²]	S
Area fraction of freshwater, region (total)	1E-03	[−]	O
Area fraction of seawater, region (total)	1E-05	[−]	O
Area fraction of natural soil, region (total)	0.01	[−]	O
Area fraction of agricultural soil, region (total)	0.979	[−]	O
Area fraction of industrial/urban soil, region (total)	0.01	[−]	O

Area (land+rivers) of regional system	0.1	[km²]	S
Area fraction of freshwater, region (excl. sea)	9E-03	[−]	S
Area fraction of natural soil, region (excl. sea)	0.01	[−]	S
Area fraction of agricultural soil, region (excl. sea)	0.971	[−]	S
Area fraction of industrial/urban soil, region (excl. sea)	0.01	[−]	S
Length of regional seawater	1E-06	[km]	S
Width of regional seawater	1E-06	[km]	S
Area of regional seawater	1E-06	[km²]	S
Area (land+rivers+sea) of regional system	0.1	[km²]	S
Area fraction of freshwater, region (total)	1E-03	[−]	O
Area fraction of seawater, region (total)	1E-05	[−]	O
Area fraction of natural soil, region (total)	0.01	[−]	O
Area fraction of agricultural soil, region (total)	0.979	[−]	O
Area fraction of industrial/urban soil, region (total)	0.01	[−]	O

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DOI: https://doi.org/10.2478/oszn-2025-0020 | Journal eISSN: 2353-8589 | Journal ISSN: 1230-7831

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Language: English

Page range: 1 - 17

Published on: Mar 17, 2026

Published by: National Research Institute, Institute of Environmental Protection

In partnership with: Paradigm Publishing Services

Keywords:

PEC,

FOCUS,

PWC,

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© 2026 Marta Gabryszewska, Barbara Gworek, Beata Kubiak, Radosław Kalinowski, Marta Kijeńska-Markuszewska, Adriana Solecka, Magdalena Graniewska, Izabela Samson-Bręk, published by National Research Institute, Institute of Environmental Protection
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 36 (2025): Issue 4 (December 2025)

Models for Calculating Predicted Environmental Concentrations (PEC) of Pesticides in Surface Waters: Review, Selection Criteria, and Recommendations for Regulatory Applications

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