UNITED ST A TES ENVIRONMENT AL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

MEMORANDUM 

DATE: September 19, 2015 

SUBJECT: d-Limonene: PRD Response to Comments on Registration Review 

Preliminary Risk Assessment 

Caitlin N ewcamp, Chemical Review Man ~r 

Thomas Moriarty, Team Leader t---

FROM: 

Risk Management and Implementation Branch 1 

Pesticide Re-evaluation Division (7508P) /J n 

THROUGH: Neil Anderson, Branch Chief /~ 1~'-----__, Risk Management and Implementation Branch 1 

Pesticide Re-evaluation Division (7508P) 

TO: d-limonene Registration Review Docket 

Docket Number: EPA-HQ-OPP-2010-0673 

www.regulations.gov 

SUMMARY OF COMMENTS AND AGENCY RESPONSES 

During the 60-day public comment period on the d-limonene Preliminary Risk Assessment, 

which opened on 12/24114 and closed on 2/23/15, the Agency received five public comments. 

Comments were submitted by the Center for Biodiversity (CBD) and at least one member of the 

general public. Of the comments submitted by the general public, one (EPA-HQ-OPP-2010-

0673-0022) was with regard to the use of d-limonene as an active ingredient in pet care products. 

B. Hughes (EP A-HQ-OPP-2010-0673-0022) 

The commenter provided information on incidents related to domestic animals, and commented 

that d-limonene should not be in products intended for pets. 

EPA Response: In response to the comment from B. Hughes, the Agency conducted a review of 

its database (the Incident Database System) for adverse incidents related to domestic animals and 

limonene/d-limonene, see Limonene and d-Limonene: Review of Domestic Animal Incidents 

(S.Recore; Sep, 2015) in the docket EPA-HQ-OPP-2010-0673 accessible at 

www.regulations.gov. 

The Agency's review captured incidents from January 1, 2010 to July 9, 2015, during which time 

a total of 231 incidents involving domestic animals and either limonene or d-limonene were 

identified. Domestic pet incident information is submitted to the Agency as aggregate exposure 

counts, so information beyond exposure severity and year of the incident is not provided. The 

231 incidents were categorized as follows: 6% fatal, 4% major, 18% moderate, 71 % minor and 

1 % unspecified. Minor incidents are designated by the animal exhibiting symptoms that were 

minimally bothersome and resolved rapidly. The 231 incidents were associated with 10 different 

d-limonene products (i.e. not just pet care products but, insect sprays, agricultural products, etc.). 

Only one of the products associated with the 231 incidents is labelled for direct application to a 

pet (2724-759, Holiday Flea and Tick Shampoo, containing 5% d-limonene active ingredient). In 

the Agency's analysis, this one product accounted for the majority of overall pet incidents (82%) 

as well as the majority of fatal or major incidents (20 out of 24). 

To better understand the character of the incidents associated with the d-limonene pet shampoo 

product, the Agency contacted the registrant of product 2 724-7 5 9, W ellmark International. 

Narrative information (i.e. , more detailed information such as species, age, route of exposure, 

etc.) regarding incidents with this product was provided by Wellmark International. This 

information indicated that many of the incidents (43%, n=l 18) involving product 2724-759 were 

associated with unintended exposure (e.g., ocular or oral exposure) or use of the product in a 

manner inconsistent with the label (use on animal below permitted age, product left on animal 

for extended time period, etc.). Wellmark also provided the Agency with sales data for the 

subject product. When the sales data is compared with incident data, a low incident rate is 

suggested: 0.02% or 2 per 10,000 units sold. By acknowledging that each unit would likely be 

used multiple times, the incident rate would decrease even further. 

Based on the available information, i.e., the Agency's analysis and incident information from the 

registrant, the Agency notes that not all incidents involving d-limonene and domestic pets are 

attributed to the intended use of the pet shampoo containing d-limonene as the active ingredient. 
In addition, when considering the number of incidents that may be associated with the use of the 

d-limonene pet shampoo product, and the volume of product sold, the Agency does not believe 

there is a significant concern of risk to domestic pets from product 2724-759 at this time. 

However, given the inherent potential risk from the direct application of an insecticidal pet 

product, the Agency reviewed the product label to identify measures to strengthen or clarify the 

product label in an attempt to reduce risk of future incidents. As a result, W ellmark International 

indicated that it would include additional information that specifies the appropriate age and 

weight of a cat or dog on which the subject product can be used.