The risk assessment below is based on the final list of endpoints for 6-benzyladenine from the EFSA conclusion (ESFA Journal 2010; 8(9): 1716) . In addition, new studies for the assessment of MaxCel were submitted and evaluated by Ctgb. The tested formulation is referred to as VBC-30127. VBC 30127 has the same composition as MaxCel in the current application and contains 1.88 % w/w of 6- benzyladenine. These additional data are added in Italic.
List of Endpoints Ecotoxicology
Effects on terrestrial vertebrates (Annex IIA, point 8.1, Annex IIIA, points 10.1 and 10.3)
Species Test substance Time scale End point
(mg/kg bw/day)
End point (mg/kg feed) Birds ‡
Bobwhite quail. 6-benzyladenine Acute 1 599
Preparation Acute No data required
Metabolite Acute No metabolite
6-benzyladenine Short-term > 2875 > 5620
6-benzyladenine. Long-term 41.3 500
Mammals ‡
Rat. 6-benzyladenine Acute 1584
MAXCEL Acute > 5000 mg prep./kg bw
Metabolite Acute No metabolite
6-benzyladenine Long-term 30 400
Additional higher tier studies ‡ No data required
Toxicity data for aquatic species (most sensitive species of each group) (Annex IIA, point 8.2, Annex IIIA, point 10.2)
Test substance Time-scale (Test type)
End point Toxicity (mg/L)
Laboratory tests ‡ Fish
Brachydanio rerio
6-benzyladenine
96 hr (semi-static)
Mortality, LC50 32-56 (nom)
Oncorhynchus mykiss VBC-30127* 96 hr
(static)
Mortality, LC50 32 mg form/L (0.60 mg a.s./L)(A)
Test substance Time-scale (Test type)
End point Toxicity (mg/L)
Aquatic invertebrate
Daphnia magna
6-benzyladenine
48 h (semi-static)
Mortality, EC50 13.4-22.1 (mm)
Mortality, EC50 >129 mg form/L (>2.43 mg a.s./L)(A) Sediment dwelling organisms
Chironomus riparius.
6-benzyladenine
28 d (static)
NOEC, Emergence 4.52 (mm, water phase)
Algae
Pseudokirchneriella subcapitata (syn. Selenastrum capricornutum)
Navicula pelliculosa
6-benzyladenine Pseudokirchneriella subcapitata VBC-30127 72 h
(static)
Growth rate: ErC50
EyC50
NOErC
>100 mg form/L (>1.88 mg a.s./L)(A)
Navicula pelliculosa VBC-30127 72 h (static)
Yield based on dry weight, EC50
57.3 mg form/L (1.04 mg a.s./L)(A) Microcosm or mesocosm tests
Not required
1 *VBC 30127 contains 1.88 %ww of 6- benzyladenine)
Bioconcentration
Active substance
Metabolite1 Metabolite2 Metabolite3
logPO/W 2.16 No relevant metabolites
Bioconcentration factor (BCF)1 ‡ -
1 only required if log PO/W >3.
Effects on honeybees (Annex IIA, point 8.3.1, Annex IIIA, point 10.4)
Test substance Acute oral toxicity (LD50 µg a.s./bee) Acute contact toxicity (LD50 µg a.s./bee)
6-benzyladenine ‡ > 58.73 > 100
MaxCel >400 >400
Field or semi-field tests Not required
1 Formulation endpoints are expressed in terms of µg a.s./bee
Effects on other arthropod species (Annex IIA, point 8.3.2, Annex IIIA, point 10.5)
Laboratory tests
1 Formulation endpoints are expressed in terms of g a.s./ha
Extended laboratory studies, semi-field or field tests Not required
Effects on earthworms, other soil macro-organisms and soil micro-organisms (Annex IIA points 8.4 and 8.5.
Annex IIIA, points, 10.6 and 10.7)
Test organism Test substance Time scale End point
Earthworms
Eisenia fetida 6-benzyladenine ‡ Acute 14 days LC50corr1
> 500 mg a.s./kg d.w.soil 6-benzyladenine ‡ Chronic 8 weeks Not required
Preparation Acute or chronic Not required
Metabolite Acute or chronic No relevant soil metabolite Other soil macro-organisms
Not required (1 application p.a., DT90lab in soil: 3.3 - 4 days) Soil micro-organisms
Nitrogen mineralisation 6-benzyladenine ‡ 28 days 2.93% effect at day-28 at 0.2 mg a.s./kg dw soil
1.1% effect at day-28 at 1.0 mg a.s./kg dw soil
(both <25% Annex VI trigger) Metabolite No relevant soil metabolite
Carbon mineralisation 6-benzyladenine ‡ 28 days -2.4% effect at day-28 at 0.2 mg a.s./kg dw soil
-19.9% effect at day-28 at 1.0 mg a.s./kg dw soil
(both <25% Annex VI trigger) Metabolite No relevant soil metabolite
Field studies Not required
1 End point has been corrected due to log Pow >2.0.
Effects on non target plants (Annex IIA, point 8.6, Annex IIIA, point 10.8) Preliminary screening data
Not required for plant growth regulators as ER tests should be provided
Species Test
Substance
Type of test Endpoint Effect
(g a.s./ha) Typhlodromus pyri VBC 30127 Laboratory (glass) Mortality LR50 >300 Aphidius rhopalosiphi VBC 30127 Laboratory (glass) Mortality LR50 146.4
Laboratory dose/rate: response tests
Test type Test substance Most sensitive species ER50
Seedling emergence 6-benzyladenine Ryegrass 1.27 mg a.s./kg soil
(plant dry weight)
Vegetative vigour MaxCel Mung bean and tomato >450
1 Formulation endpoint is expressed in terms of g a.s./ha.
Additional studies (e.g. semi-field or field studies) No data required.
Effects on biological methods for sewage treatment (Annex IIA 8.7)
Test type/organism end point
Activated sludge test > 1000 mg a.s./L
Pseudomonas sp. No data required
Ecotoxicologically relevant compounds (consider parent and all relevant metabolites requiring further assessment from the fate section)
Compartment
Soil Parent (6-benzyladenine)
Water Parent (6-benzyladenine)
Sediment Parent (6-benzyladenine)
Groundwater Parent (6-benzyladenine)
Classification and proposed labelling with regard to ecotoxicological data (Annex IIA, point 10 and Annex IIIA, point 12.3)
RMS/peer review proposal
Active substance R 50
7.1 Effects on birds
Birds can be exposed to the active substance 6-benzyladenine via natural food (sprayed insects, seeds, leafs), drinking water and as a result of secondary poisoning.
The threshold value for birds is based on the trigger from the RGB. This means that Toxicity-Exposure Ratio’s (TERs) for acute and short-term exposure should be 10 and TER for chronic exposure should be 5.
Table E.1 presents an overview of toxicity data.
Table E.1 Overview of toxicity data for birds
Endpoint Value
Acute toxicity to birds: LD50 1599 mg a.s./kg bw Dietary toxicity to birds: LC50 > 2875 mg a.s./kg bw/d Reproductive toxicity to birds: NOEL 41.3 mg a.s./kg bw/d 7.1.1 Natural food and drinking water
Sprayed products
Procedures for risk assessment for birds comply with the recommendations in the Guidance Document on Risk Assessment for Birds and Mammals under Council Directive 91/414/EEC (EFSA, 2009).
For the current application, uses can be categorized as orchards. Depending on the crop category, different indicator species are chosen. Table E.2 shows which indicator species are relevant for which uses.
Table E.2 Indicator species per use
Use Crop Indicator species
Apple, pear orchards Small insectivorous bird
Table E.3 a-c show the TER values for birds. The estimated daily uptake values (ETE, Estimated Theoretical Exposure) for acute, short-term and long-term exposure are calculated using the Food Intake Rate of the indicator species (FIR) divided by the body weight of the indicator species (bw), the Residue per Unit Dose (RUD), a time-weighted-average factor (fTWA, only for long term) and the application rate. For uses with frequency > 1, a MAF (Multiple Application Factor) may be applicable.
The ETE is calculated as application rate * (FIR/bw) * RUD * MAF [* fTWA, only for long term]. The ETE is compared to the relevant toxicity figure. TER should be above the trigger for an acceptable risk.
Table E.3a Acute risk for birds
Use FIR / bw RUD Small insectivorous bird
Orchards: apple and pear
0.86 54.1 0.225 n.a. 10.5 1599 151.9
Table E.3b Short-term risk for birds
Use FIR / bw RUD
Applica-tion rate (kg a.s./ha)
MAF Short-term ETE Small insectivorous bird
Orchards: apple and pear
0.86 21 0.225 n.a. 4.1 > 2875 > 702.1
Table E.3c Long-term risk for birds
Use FIR / bw RUD
Small insectivorous bird Orchards: apple and pear
0.86 21 0.225 n.a. 0.53 2.2 41.3 19.1
Taking the results in Table E.3a-c into account, it appears that all proposed uses meet the standards laid down in the RGB.
EFSA/2009/1438 proposes an assessment methodology for the risk to birds from active substances in drinking water using small granivorous birds as indicator species in tier 1. Two scenarios have been identified: the leaf scenario and the puddle scenario. The leaf scenario is relevant for leaf vegetables (forming heads) and other leaf vegetables whit a morphology that facilitates collection of
rain/irrigation water in reservoirs that are large enough and easily accessible to attract birds and sufficiently stable over some hours. The puddle scenario is relevant for all types of application that may cause contamination of soil.
Leaf scenario
The leafy vegetables forming heads, according to BBCH are cabbage, Chinese cabbage, lettuce, and endive. The type of crops are not included in the current request for authorization. Therefore the leaf scenario is not relevant.
Puddle scenario
Birds may be exposed to residues of the product by drinking water in puddles formed on the soil surface of a field when a (heavy) rainfall event follows the application of a plant protection product to a crop or bare soil within or close to the target area. This is relevant for all uses of product and should therefore be assessed. According to the EFSA Journal (2009), the concentration in puddles (PECpuddle) is calculated by the following equation:
s) Koc (ω 1000
AR/10 (mg/L)
PECpuddle
With:
AR = Application rate in g/ha; divisor of 10 to achieve rate in mg/m² ω = 0.02 (pore water term: volume)
s = 0.0015 (soil term: volume, density, organic carbon content) KOC = 896 L/kg
Since the product will be applied once per year a MAF (Multiple Application Factor) of 1 has to be considered in the calculations.
In cases of multiple applications a MAF (Multiple Application Factor) has to be applied based on the DT50 in soil to achieve the effective application rate AReff.
ki nki m
eff 1 e
e M AF 1
AR
AR
ARx
With:
AR = 225 g a.s/ha MAFm = 1
k = ln(2)/DT (rate constant) n = Number of applications i = Application interval
Based on the above, the AReff is 225 g a.s./ha.
Due to the characteristics of the exposure scenario in connection with the standard assumptions for water uptake by animals, no specific calculations of exposure and TER are necessary when the ratio of effective application rate (in g/ha) to acute and long-term endpoint (in mg/kg bw/d) does not exceed 50 (KOC ≤ 500 L/kg) or 3000 (KOC ≥ 500), as specified in EFSA GD, 2009. Considering the AReff of 225 g a.s./ha and the lowest endpoint of 41.3 mg/kg bw/ d, the ratio is 5.4. This value does not exceed 3000 and therefore the calculations for puddle scenario are not necessary.
7.1.2 Secondary poisoning
The risk as a result of secondary poisoning is assessed based on bioconcentration in fish and worms.
Since the log Kow of -benzyladenine < 3 (2.16), the potential for bioaccumulation is considered low and no further assessment is deemed necessary.
Conclusions birds
The product complies with the RGB.
7.2 Effects on aquatic organisms 7.2.1 Aquatic organisms
The risk for aquatic organisms is assessed by comparing toxicity values with surface water exposure concentrations from section 6.2. Risk assessment is based on toxicity-exposure ratios (TERs).
Toxicity data for aquatic organisms are presented in Table E.4. Because the application for
authorisation concerns a plant growth regulator, also the effects on macrophytes (aquatic plants) are evaluated.
No data on chronic toxicity of 6-benzyladenine to fish is available. During EU review (DAR) the following was stated: “The active substance, 6-benzyladenine, degrades rapidly in the
water/sediment system (DT50 of 2.4-4.1 days in the water and 8.6-17.1 days in the whole system).
Moreover, the Good Agricultural Practices recommend one application per year. Therefore, the continuous or repeated exposure to the formulated product and then to the active substance is unlikely. Therefore a chronic fish toxicity study was not necessary.”
Formally, a long-term or chronic toxicity study on fish is required for all substances where exposure of surface water is likely and the substance is deemed to be stable in water, i.e. there is less than 90% loss of the original substance over 24 hours via hydrolysis. However, since fish are not the most sensitive organisms, and a chronic test with Daphnia is available, the absence of a chronic test with fish is considered acceptable.
Table E.4 Overview toxicity endpoints for aquatic organisms
Substance Organism Lowest Toxicity value
L(E)C50
[mg/L]
NOEC [mg/L]
[g/L]
6-benzyladenine Acute
Algae 7.6 7600
Invertebrates 13.4 13400
Fish 32 32000
Macrophytes 0.31 310
Chronic
Invertebrates 4.0 4000
Fish no
VBC 30127 Acute
Algae 0.10 104
Invertebrates 2.43 2430
Fish 0.60 602
Macrophytes 1.04 1040
Chronic Invertebrates Fish
These toxicity values are compared to the surface water concentrations calculated in section 6.2.
Trigger values for acute exposure are 100 for invertebrates and fish (0.01 times the lowest L(E)C50 -value) and 10 for algae and macrophytes (0.1 times the lowest EC50-value). Trigger values for chronic exposure are 10 for invertebrates and fish (0.1 times the lowest NOEC-values).
For acute and chronic risk, the initial concentration is used (PIEC) for TER calculation.
In Table E.5a-b TER values for aquatic organisms are shown.
Table E.5a TER values: acute Use Substance PECsw
[g a.s./L]
TERst
(trigger 10)
TERst
(trigger 100)
TERst
(trigger 100)
TERst
(trigger 10)
Algae Invertebrates Fish Macrophytes Apples
6-benzyladenine
7.49 13.89 324.43 80.11 41.39
Pears
6-benzyladenine
6.66 15.62 364.87 90.09 46.55
Table E.5b TER values: chronic
Use Substance PECsw
[g a.s./L] TERlt
(trigger 10) Invertebrates
Apples 6-benzyladenine 7.49 534
Pears 6-benzyladenine 6.66 600
Taking the results in Table E.5a-b into account, the acute TERs for algae and Lemna are above the relevant Annex VI triggers of 10 and the acute TER for invertebrates is above the relevant Annex VI trigger of 100.
The chronic TER for invertebrates is above the relevant Annex VI trigger of 10.
The acute TER for fish is below the relevant Annex VI trigger of 100. A risk for aquatic organisms cannot be excluded. Drift reduction is needed. The following drift reduction measures are possible:
- Use of Standard orchard sprayer in combination with windbreak on the edge of the driving track and one-sided spraying of the last tree row
- Use of Tunnel sprayer
- Use of Wanner equipment with reflection shield
- Use of at least 50% drift reducing nozzle and one-sided spraying of the last tree row - Use of KWH k1500-3R2 VLOS 3-row sprayer with variable air support system.
[in Dutch]
- een windhaag op de rand van het rijpad in combinatie met éénzijdige bespuiting van de laatste bomenrij in de richting van het perceel met inachtneming van een teeltvrije zone van tenminste 3 meter;
- een tunnelspuit met inachtneming van een teeltvrije zone van tenminste 3 meter;
- een Wannerspuit met reflectieschermen en standaard spuitdoppen met inachtneming van een teeltvrije zone van tenminste 3 meter;
- minimaal 50 % driftreducerende spuitdoppen in combinatie met éénzijdige bespuiting van de laatste bomenrij in de richting van het perceel met inachtneming van een teeltvrije zone van tenminste 3 meter;
- een KWH k1500-3R2 VLOS 3-rijenspuit met variabele luchtondersteuning en standaard spuitdoppen in de eerste 20 meter grenzend aan het oppervlaktewater met inachtneming van een teeltvrije zone van tenminste 3 meter
7.2.2 Risk assessment for bioconcentration
Since logKow of 6-benzyladenine (1.86-2.16 in pH range 4-9) is < 3, experimental data are not required. A BCF-value of 14 L/kg can be calculated from logKow 2.16. Since this value is below 100 L/kg, the risk for bioconcentration is small. Therefore the active substance 6-benzyladenine meets the standards for bioconcentration as laid down in the RGB.
7.2.3 Risk assessment for sediment organisms
The NOEC value for Chironomus is 4520 µg/L. When this value is examined against the PIEC in water, the TER value is 603.47 and the trigger value of 10 is met. Therefore, the active substance
6-benzyladenine meets the standards for sediment organisms as laid down in the RGB.
Conclusions aquatic organisms
The product complies with the RGB, provided that drift reduction measures are applied.
7.3 Effects on terrestrial vertebrates other than birds
Mammals can be exposed to the active substance 6-benzyladenine via natural food (sprayed insects, seeds, leafs), drinking water and as a result of secondary poisoning.
The threshold value for mammals is based on the trigger from the RGB. This means that the Toxicity-Exposure Ratio (TER) for acute exposure should be 10 and TER for chronic exposure should be 5.
Dietary toxicity is not taken into account for mammals.
Table E.6 Overview of toxicity data for mammals
Endpoint Value
Acute toxicity to mammals: LD50 1584 mg a.s./kg bw/d Reproductive toxicity to mammals: NOEL 30 mg a.s./kg bw/d 7.3.1 Natural food and drinking water
Sprayed products
Procedures for risk assessment for mammals comply with the recommendations in the Guidance Document on Risk Assessment for Birds and Mammals under Council Directive 91/414/EEC (EFSA, 2009).
For the current application, uses can be categorized as orchard. Depending on the crop category different indicator species are chosen. Table E.7 shows which indicator species are relevant for which uses.
Table E.7 Indicator species per use
Use Crop Indicator species
Apple, pear orchards Small herbivorous mammal
Table E.8 a-b show the estimated daily uptake values (ETE, Estimated Theoretical Exposure) for acute and long-term exposure, using the Food Intake Rate of the indicator species (FIR) divided by the body weight of the indicator species (bw), the Residue per Unit Dose (RUD), a time-weighted-average factor (fTWA, only for long term) and the application rate. For uses with frequency of > 1, a MAF (Multiple Application Factor) may be applicable. The ETE is calculated as application rate * (FIR/bw) * RUD * MAF [* fTWA, only for long term]. The ETE is compared to the relevant toxicity figure. TER should be above the trigger for an acceptable risk.
Table E.8a Acute risk for mammals
Use FIR / bw RUD small herbivorous mammal
Orchards: apple and pear
1.33 102.3 0.225 n.a. 30.6 1584 51.7
Table E.8b Long-term risk for mammals
Use FIR / bw RUD
small herbivorous mammal Orchards: apple and
pear
1.33 54.2 0.225 n.a. 0.53 8.6 30 3.5
Taking the results in Table E.8a-b into account, it appears that all proposed uses have a low acute risk for mammals, but that a long-term risk cannot be excluded. Therefore a Tier 1 long-term risk
assessment is performed for all relevant scenarios in line with the intended use (BBCH > 40, see Table E.0).
The tier 1 risk assessment for relevant long-term risk for birds is shown in Table E.9.
Table E.9 Long-term risk for birds, tier 1 risk assessment Scenario Indicator species Mean
RUD
directed BBCH ≥ 40
Small herbivorous mammal "vole"
54.2 2.572 11.7
Fruit stage BBCH 71-79 currants directed BBCH ≥ 40 directed BBCH ≥ 40
Small omnivorous mammal "mouse"
29.2 0.273 110.1
Taking the results in Table E.9 into account, it appears that all proposed uses meet the standards laid down in the RGB.
drinking water
EFSA/2009/1438 proposes an assessment methodology for the risk to mammals from active substances in drinking water using small granivorous mammal as indicator species in tier 1. Two scenarios have been identified: the leaf scenario and the puddle scenario. The leaf scenario is relevant for leaf vegetables (forming heads) and other leaf vegetables whit a morphology that facilitates collection of rain/irrigation water in reservoirs that are large enough and easily accessible to attract mammals and sufficiently stable over some hours. The puddle scenario is relevant for all types of application that may cause contamination of soil.
Leaf scenario
The leafy vegetables forming heads, according to BBCH are cabbage, Chinese cabbage, lettuce, and endive. The type of crops are not included in the current request for authorization. Therefore the leaf scenario is not relevant.
Puddle scenario
Mammals may be exposed to residues of the product by drinking water in puddles formed on the soil surface of a field when a (heavy) rainfall event follows the application of a plant protection product to a crop or bare soil within or close to the target area. This is relevant for all uses of product and should therefore be assessed. According to the EFSA Journal (2009), the concentration in puddles (PECpuddle) is calculated by the following equation:
s) Koc (ω 1000
AR/10 (mg/L)
PECpuddle
With:
AR = Application rate in g/ha; divisor of 10 to achieve rate in mg/m² ω = 0.02 (pore water term: volume)
s = 0.0015 (soil term: volume, density, organic carbon content) KOC = 896 L/kg
Since the product will be applied once per year a MAF (Multiple Application Factor) of 1 has to be considered in the calculations.
In cases of multiple applications a MAF (Multiple Application Factor) has to be applied based on the DT50 in soil to achieve the effective application rate AReff.
ki nki m
eff 1 e
e M AF 1
AR
AR
ARx
With:
AR = 225 g a.s/ha MAFm = 1
k = ln(2)/DT (rate constant) n = Number of applications i = Application interval
Based on the above, the AReff is 225 g a.s./ha.
Due to the characteristics of the exposure scenario in connection with the standard assumptions for water uptake by animals, no specific calculations of exposure and TER are necessary when the ratio of effective application rate (in g/ha) to acute and long-term endpoint (in mg/kg bw/d) does not exceed 50 (KOC ≤ 500 L/kg) or 3000 (KOC ≥ 500), as specified in EFSA GD, 2009. Considering the AReff of 225 g a.s./ha and the lowest endpoint of 30 mg/kg bw/ d, the ratio is 7.5. This value does not exceed 3000 and therefore the calculations for puddle scenario are not necessary.
7.3.2 Secondary poisoning
The risk as a result of secondary poisoning is assessed based on bioconcentration in fish and worms.
Since the log Kow of -benzyladenine < 3 (2.16), the potential for bioaccumulation is considered low and no further assessment is deemed necessary.
Conclusions mammals
The product complies with the RGB.
7.4 Effects on bees
The risk assessment for bees is based on the Hazard Quotient (HQ), the ratio between the highest single application rate and toxicity endpoint (LD50 value). An overview of the risk at the proposed uses is given in Table E.10.
Table E.10 In-field risk for bees
Use Substance Application rate LD50 HQ
(Rate/LD50)
Trigger value [g a.s./ha] [µg/bee]
all
6-benzyladenine
225 7.3 30.82 50
Since the HQ is below 50, the risk for bees is considered to be low. Hence, all proposed uses meet the standards for bees as laid down in the RGB.
Conclusions bees
The product complies with the RGB.
7.5 Effects on any other organisms (see annex IIIA 10.5-10.8)
7.5.1 Effects on non-target arthropods
The risk for non-target arthopods is assessed by calculating Hazard Quotients. For this, Lethal Rate values (LR50) are needed. Based on LR50-values from studies with the two standard species Aphidius rhopalosiphi and Typhlodromus pyri an in-field and an off-field Hazard Quotient (HQ) can be calculated according to the assessment method established in the SETAC/ESCORT 2 workshop and
The risk for non-target arthopods is assessed by calculating Hazard Quotients. For this, Lethal Rate values (LR50) are needed. Based on LR50-values from studies with the two standard species Aphidius rhopalosiphi and Typhlodromus pyri an in-field and an off-field Hazard Quotient (HQ) can be calculated according to the assessment method established in the SETAC/ESCORT 2 workshop and