Document ID: EPA-HQ-OPP-2015-0023-0013
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2015-11-13T05:00Z

Ecological Effects and Endangered Species Risk Assessment for Choline Chloride

Choline chloride a quaternary ammonium salt is miscible with water in all proportions and has a measured water solubility of 650 g/L. Due to the measured and calculated log Kow of  - 3.77 and  - 5.15, respectively, and the calculated log Koc of 0.37, bio- and geoaccumulation are not to be expected. Choline chloride was shown to be readily biodegradable according to OECD criteria in a MITI I-Test within 14 days. In the atmosphere, the substance will be rapidly indirectly photodegraded by reaction with OH-radicals (calculated t (1/2) = 6.9 h) based on a 12h-day. 

Terrestrial Species

The Agency has estimated potential acute toxicity end points for avian and mammalian species (LD50 = 3,129 mg/kg) and calculated potential risk using the Terrestrial Residue Exposure Model (T-REX) Version 1.4.1 for the orchard spray application of CP Bio, Choline Chloride 20% SP at the maximum rate of 0.282 lbs ai/A (Appendix B). The T-REX model using Kenega values produced low dose-based values and risk quotients (RQs) that were at least one to two orders of magnitude (0.00  -  0.06) below the EPA Levels of Concern (LOC) of 0.1 for avian and mammalian endangered species. The possible effect to honey bees is also very low with an LD50> 89 ug ai/bee (RQ < 0.09). The Agency also conducted a search (10/09/2015) of the Ecological Incident Information System version 2.1.1 (EIIS) and did not find any reports of detrimental exposure of choline chloride to terrestrial species. This low risk to non-target terrestrial species suggests that the potential for toxic exposure to endangered/ threatened species is also very low. The Agency calculated the chance of individual terrestrial exposure and risk by using the Individual Effects Chance Model (Version 1.1) which suggest that the chance of effects to a terrestrial species from choline chloride exposure is about 1 in 2,940,000 (predictor of chance of individual effect using Probit dose-response curve slope and median lethal estimate Appendix C) which may be considered as a highly unlikely event.  The low toxic risk of choline chloride to terrestrial organisms (RQ = 0.0  -  0.6), the short environmental half-life (7 days), the low maximum concentration of choline chloride to be applied per season (128.0 g/A), and an understanding of the mode of action of this compound (plant growth regulator) show that there is a very low potential for toxic risk to terrestrial species. Based on the proceeding information, choline chloride presents a No Effect (NE) to threatened or endangered terrestrial species, if used in accordance with approved labeling.

Aquatic Species
 
Choline chloride is very water soluble (690 g/L) but exposure to aquatic species is not expected to result in acute toxicity. The Agency conducted a worst case scenario using the aquatic model FIRST Ver 1.1.1 to assess the potential exposure of runoff and drift from the maximum application of choline chloride formulation to an aquatic area (Appendix A).  Using the EPA LOC values for aquatic listed species (0.05), the expected peak estimated environmental concentration of 0.060 ppm, and assuming that 0.282 lbs ai/A, RQ values were calculated at 0.00 showing no acute toxicity risk to aquatic species. The Agency conducted a search (10/09/2015) of the Ecological Incident Information System (EIIS, version 2.1), the `Aggregate Incident Reports' (v. 1.0) database, for ecological incidents involving choline chloride and no aquatic incidents were reported. The Agency also calculated the chance of individual fish and aquatic invertebrate exposure and risk by using the Individual Effects Chance Model (Version 1.1). These calculations suggest that the chance of effects to aquatic invertebrates (food source) or to fish from methyl choline chloride is about 1 in 418,000,000 (Appendix C), which may be considered as a highly unlikely event. Therefore, the Agency concludes a No Effect (NE) to aquatic endangered/ threatened species because of the lack of potential for direct or indirect toxic risk to aquatic ecological systems from exposure to choline chloride. 

Plants (Aquatic and Terrestrial)

Concentration levels of choline in plants can range from 28  -  589 ppm. The environmental residue levels of choline chloride after direct application to foliage were calculated from the T-Rex model and showed a range of 7.93  -  126.90 ppm. According to the assumptions of the EPA FIRST Ver. 1.1.1 aquatic model there is an expected 8% drift from orchard spraying that could result in 0.63  -  10.15 ppm residues onto adjacent vegetative sites. These expected environmental concentration to non-target plants are at or below the background levels found in plants. Choline chloride is non-toxic to plants and any indirect effects to non-target plants that could be considered habit for endangered/threatened species is expected to be No-Effect. 

Conclusion

The unique characteristics of this product, choline chloride, the non-toxic mode of action (plant growth regulator), biodegradability (7 day half-life), photo degradation (6.9 hours), no bioaccumulate (Log Koc = 0.37) and low potential for exposure (maximum application of 0.282 lbs ai/A 4 times /season) will result in no acute direct or indirect toxic risk to non-target organisms, including threatened and endangered species. Based on the proceeding information, choline chloride presents a No Effect (NE) to threatened or endangered terrestrial or aquatic species (plants or animals), if used in accordance with approved labeling.

References
MOE Japan (1999). Ministry of Environment. Acute toxicity study of choline chloride on the
freshwater alga Pseudokirchneriella subcapitata unpublished study. No. 1998-13.
BASF AG (2003). Department of Product Safety. Laboratory of Ecology. Hemmung der
Algenzellvermehrung nach DIN 38412 L9: "78% choline chloride dissolved in water". Unpublished data. Reprint of report No. 09908 (06 Nov 1989). 16 Sept. 2003.

Appendix A.0 Calculate Water Concentrations for Choline Chloride using FIRST Ver 1.1.1  MAR 26, 2008

Table A.1 Water Concentration for Choline Chloride after Application to Stone Fruits at 0.282 lbs/A     
   -------------------------------------------------------------------------------------------------------------------
    RATE (#/AC)       No. APPS &   SOIL   SOLUBIL   APPL TYPE    %CROPPED   INCORP
     ONE (MULT)      INTERVAL    Koc       (PPM)    (%DRIFT)            AREA           (IN)
   -------------------------------------------------------------------------------------------------------------------
  0.282 (0.722)           4          7       0.4      *******      ABLAST (6.3)    87.0                0.0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)
   --------------------------------------------------------------------
   METABOLIC   DAYS UNTIL     HYDROLYSIS   PHOTOLYSIS   METABOLIC   COMBINED
    (FIELD)            RAIN/RUNOFF   (RESERVOIR)   (RES.-EFF)       (RESER.)            (RESER.)
   -----------------------------------------------------------------------------------------------------------------------
      14.00                               0                   14                  0.29-   35.96        14.00                 10.08

   UNTREATED WATER CONCENTRATION (PPB)) 
   --------------------------------------------------------------------
        PEAK DAY (ACUTE)                 ANNUAL AVERAGE (CHRONIC)
   ------------------------------------------------------------------------------------------------------------
                    60.101                                       1.792

   

Appendix B.0 T-REX Output for Choline Chloride Exposure to Avian and Mammalian Species after 
Table B.1 Terrestrial Residue Exposure Model (T-REX) Version 1.4.1 Application to Stone Fruit 

The application of CP Bio, Choline Chloride 20% SP at the maximum rate of 0.282 lbs ai/A does not pose an acute risk to nontarget or threatened avian or mammalian species. Risk quotients (RQs) were generated using the acute mammalian LC50 = 3,129 mg/kg. The T-REX model using Kenega values produced low dose-based values and RQs that were at least one to two orders of magnitude (0.00  -  0.06) below the EPA Levels of Concern (LOC) of 0.1 for avian and mammalian endangered species.

Appendix C.0 Individual Effects Chance Model for Terrestrial and Aquatic Species
Table C.1.  Individual Effects Chance Model Version 1.1 for Predicting the Chance of Individual Effects of Choline Chloride to Terrestrial Endangered Species
IEC V1.1 - Individual Effect Chance Model Version 1.1
 
Predictor of chance of individual effect using Probit dose-response curve slope and median lethal estimate 
 
Enter LC50 or LD50
                                                                           3129
 
 
Enter desired threshold 
                                                                            0.1
 
 
Enter slope of dose-response
                                                                            4.5
                                                                               
 
z score result
                                                                           -4.5

 
Probability associated with z
                                                                       3.40E-06

Chance of individual effect,                  ~1 in .  .  .
                                                                       2.94E+05

 

Table C.2.  Individual Effects Chance Model Version 1.1 for Predicting the Chance of Individual Effects of Choline Chloride to Aquatic Endangered Species

IEC V1.1 - Individual Effect Chance Model Version 1.1
 
Predictor of chance of individual effect using Probit dose-response curve slope and median lethal estimate 
 
Enter LC50 or LD50
                                                                            100
 
 
Enter desired threshold 
                                                                           0.05
 
 
Enter slope of dose-response
                                                                            4.5
                                                                               
 
z score result
                                                                    -5.85463498

 
Probability associated with z
                                                                       2.39E-09

Chance of individual effect,                  ~1 in .  .  .
                                                                       4.18E+08

 

Appendix D.0 Calculated RQ Values

Table D.1 Summary of Specific Ecological Assessment Endpoints and Calculated RQ Values for Terrestrial and Aquatic Species Exposed to Choline Chloride after Application to Stone fruits
                                     TAXA
                                       
                               MEASURE OF EFFECT
                                       
                                    Species
                                   Toxicity
                                       
                                      RQ
Freshwater Fish
Acute

Rice fish (Oryzias latipes)
96 hr LC50 > 100 mg/L

0.00
Freshwater Invertebrates
Acute

Daphnia magna
EC50 =349 mg/L
0.00
Avian
Acute

Mallard duck 
(Anas platyrhynchos)[a]
LD 50 = 3,129 mg ai/kg 

0.00  -  0.6
Mammals
Acute

Rat
(Rattus norvegicus)
LD50 = 3,129 mg/kg
0.00  -  0.2
Insect 
Acute

Honey bee 
(Apis mellifera)

 LD50 > 89 ug ai/bee 

< 0.09

[a] The mammalian acute toxicity data is used as a surrogate for avian oral dose