OFFICE OF 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

TO: 

FROM: 

Approved By: 

PC Code: 019401 

DP Barcode: D419150 

June 5, 2014 

EFED Preliminary Risk Assessment to Classify Registered 4-CPA Uses as De 

Minimus Risk to Listed/Non-Listed Species and "No Effects" Determination 

Molly Clayton, Chemical Review Manager 

Tracy Perry, Team Leader 

Risk Management and Implementation Branch 3 

Pesticide Re-Evaluation Division 

Office of Pesticide Programs (7508P) 

Edward 

Environmental 

Environmen

Odenkirchen, 

tal 

Risk 

Fate and 

Bran

Ph.D., 

Effects 

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Senio

Division 

r Science Advisor V ~ 

Office of Pesticide Programs (7507P) ~J 0-'"'-~~ (0 \ b \ ~ 

Sujatha Sankula, Ph.D., Branch Chief -=:...-

Environmental Risk Branch 1 

Environmental Fate and Effects Division 

Office of Pesticide Programs (7507P) 

The Environmental Fate and Effects Division (EFED) is issuing this memorandum as a followup to the presentation to the Science Policy Council/Risk Management Forum on April23, 2014, 

in which a case was made to classify the registered uses of 4-CP A as presenting de minimus risk 

to threatened and endangered species by virtue that the use was indoors and so did not constitute 

a potentially complete exposure pathway to non-target organisms. The Forum disagreed with 

EFED's recommendation that registered uses of 4-CPA present no environmental risks to listed 

and non-listed species based on the expectation that spent greenhouse mung bean soaking 

solution could go down wastewater drains, in accordance with the pesticide label. This document 

more fully explores this exposure pathway and is based on Science Policy Council/Risk 

Management Forum discussions and a subsequent May 22, 2014 memorandum on the subject 

(USEPA 2014). 

The Office of Pesticide Program's Science Policy Council/Risk Management Forum recently 

determined that some chemicals scheduled to undergo Registration Review may not require 

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detailed risk assessments if it can be demonstrated that they are likely to pose minimal or no 

risks to listed species. The questions (criteria) considered for de minimus classification include: 

1. Are exposure pathways reasonably expected to be incomplete between the use site and 

potential environmental receptors (i.e. federally listed species)? 

2. Is the pesticide of low toxicity such that it is reasonable to expect that appreciable 

environmental loading would be necessary to produce environmental effects? 

3. Is the use ofthe pesticide so low in quantity that it is unreasonable to expect significant 

environmental loading in a particular area? 

4. Is the distribution of the pesticide use site so diffuse that it is unreasonable to expect 

significant environmental loading of the pesticide? 

Not all criteria must be met for de minimus status to be granted; chemicals will be evaluated on a 

case-by-case basis and the criteria will be weighted accordingly. 

Background 

The pesticide 4-CP A is a plant growth regulator used exclusively as a soaking agent for mung 

bean sprouts in greenhouse operations to prevent root formation and thereby improve the sorting 

and handling of the mung bean sprouts for packaging. All of the use occurs indoors. 4-CP A is 

applied in a dilute solution of 2 to 3 mg/1 active ingredient to a water bath to soak batches of 

about 3500 pounds of beans. Once the beans have soaked for several hours, they are washed to 

remove the surface residues, and are then germinated indoors for several days. After sprouting, 

the hulls and roots are discarded, and the remaining portion is packaged and sold for human 

consumption. 

Criterion #1 -Complete Exposure Pathways 

Spent mung bean soaking solution can be disposed of down municipal wastewater drains, 

consequently, it is logical to assume that some amount of 4-CPA will eventually continue to 

receiving waters. Therefore, the consideration of a completely closed indoor system with no 

reasonable pathway to non-target organisms is not supportable. 

Criterion #2- Low Toxicity 

While there is little empirically determined toxicity information, the ECOSAR quantitative 

structure activity program provides predictions that are informative and suggest a low likelihood 

for significant toxicity to aquatic organisms, the taxa most likely to be exposed via a wastewater 

discharge scenario. In many cases the predicted toxicity would be well above the solubility limit 

of the compound. And in almost all cases the predicted toxicity is in the range of low toxicity to 

practically non-toxic. 

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ECOSAR Class Organism Duration End Pt 

Neutral Organics-acid :Fish 96-hr LCSO 

Neutral Organics-acid : Daphnid 48-hr LCSO 

Neutral Organics-acid :Green Algae 96-hr EC50 

Neutral Organics-acid :Fish ChV 

Neutral Organics-acid : Daphnid ChV 

Neutral Organics-acid : Green Algae ChV 

Neutral Organics-acid :Fish (SW) 96-hr LC50 

Neutral Organics-acid : Mysid 96-hr LC50 

Neutral Organics-acid :Fish (SW) ChV 

Neutral Organics-acid : Mysid (SW) ChV 

Note: * = asterisk designates: Chemical may not be soluble enough to 

measure this predicted effect. If the effect level exceeds the 

water solubility by 1 OX, typicaliy no effects at saturation (NES) 

are reported. 

--> Acid moeity found: Predicted values multiplied by 10 

Criterion #3 -Low Quantity Used 

mg/L Crmm} 

1621.886 * 

918.599 

677.173 

158.063 

88.957 

176.344 

2041.500 * 

1545.543 * 

217.926 

134.677 

The Science Policy Council and Risk Management Forum concluded that the total amount of 4-

CP A used annually is about 20 lb. 

Criterion #4- Highly Diffuse Use Site 

The Science Policy Council and Risk Management Forum reasoned that the 20 lb of 4-CPA used 

annually is spread throughout the year. For instance, if production were to occur 50 weeks a 

year, then only 0.4lb of 4-CPA would be used each week (dilute solutions of2 to 3 mg ai/L per 

3500 pounds of beans). During the soaking period, the mung beans would absorb 2 to 3 times 

their weight (and volume) of the solution. The Forum reasoned that less than half of the 4-CPA 

amount would be left unabsorbed and would likely be subject to significant dilution before 

possible release or disposal. Dilution rates were assumed to be extensive because food 

processing lines run more or Jess continuously and the few thousand gallons of spent soaking 

solution are reasonably expected to be diluted with the entire processing facility's wastewater 

discharge. 

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From the above reasoning, the Forum concluded that the 20 lb of 4-CPA used annually would be 

greatly dispersed over time and diluted. If any 4-CP A is disposed of through sanitary sewer 

systems, the concentration of the active ingredient arriving at a publically owned treatment 

works in an individual release would be minimal. 

It should be noted that even the starting solution concentration of 2 to 3 mg/L, without dilution 

from process water, is well below estimated toxicity thresholds. 

Conclusion 

Based on the type and extent of use, the low expected toxicity shown by QSAR, and the highly 

diffuse nature of the use site coupled with extremely low annual usage, EFED concludes that 

effects on the environment are not reasonably expected to occur via the registered uses of 4-

CP A. Therefore, EFED has reached a "no effects" determination for listed species for registered 

uses of 4-CP A. Given that the threshold for effects to listed species is lower than non-listed 

species, EFED determined that effects to non-target, non-listed species are unlikely as well. 

Sources Cited 

USEPA. 2014. MEMORANDUM from: Science Policy Council/Risk Management Forum De 

Minimis Subgroup to: Richard Keigwin, Jr. Division Director, PRO, Donald Brady, 

Division Director, EFED, Dana Vogel, Acting Division Director, HED, Yu-Ting 

Guilaran, Division Director, BEAD 

ECOSAR. vl.l l Class-specific Estimations SMILES : O=C(O)COc(ccc(cl)CL)cl. 

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