UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

OFFICE OF

PREVENTION, PESTICIDES AND TOXIC 

SUBSTANCES

06/02/04

MEMORANDUM

SUBJECT: New Chemical Screen for Copper Pyrithione (088001) (Copper Omadine) 

Antifoulant Use 

FROM: Doreen Aviado - D230656

James Breithaupt - D300658

Jonathan Chen - D300000

Kathryn Montague - D300774

Siroos Mostaghimi - D300772

Richard Petrie - D300773

Bob Quick - D301743

Najm Shamim - D300657

Deborah Smegal - D300002

OPPTS/OPP/AD/RASSB

TO: Norm Cook, Chief

OPPTS/OPP/AD/RASSB

Arch Chemicals Inc. has submitted additional information in response to a previous 

RASSB denial of their new chemical package for copper pyrithione antifoulant paint (also 

referred to as copper omadine). A number of data waivers were denied by RASSB in response to 

the registrant’s previous request that zinc omadine data be used as surrogate or bridging data for 

copper omadine registration. 

No new data were submitted with the second request; however, four new items were sent 

for our consideration:

1.) United Kingdom assessment reports and risk assessments for zinc omadine and copper 

omadine antifoulant paints,

2.) An 11/13/03 response regarding the RASSB environmental fate new chemical screen;

3.) An 11/13/03 response regarding the RASSB toxicology new chemical screen; and

4.) Arch Chem. meeting minutes of a 02/25/04 meeting with RASSB staff.
−2−

Having reviewed the above cited information, RASSB concludes that copper omadine 

still does not pass the new chemical screen in the areas of toxicology and environmental fate. 

Specifically:

SCIENCE AREAS WHICH FAIL SCREEN:

TOXICOLOGY - The submitted information was discussed in the Antimicrobials Division 

Toxicology Endpoint Selection Committee (ATDC) on May 26, 2004. The committee 

concluded that insufficient data are available for bridging between copper, sodium, and zinc 

omadine. For copper omadine a 90-day oral rat study, with neurological end-points evaluated, is 

required to determine if copper omadine can bridge to sodium or zinc omadine. The primary 

reasons are:

1. Different physical chemical properties of copper, sodium, and zinc omadine will affect 

the absorption/bioavailability of the chemical;

2. A similar metabolic profile between omadines does not necessarily relate to the mode of 

action for causing effects of concern;

3. Because emesis was observed in both sodium and zinc omadine in the subchronic 

monkey study, it is difficult to estimate the real exposed concentration; and 

4. Signs of neurotoxic effects (skeletal muscle wasting, hind leg paralysis) were noticed in 

the 90-day rat oral studies for both sodium omadine and zinc omadine. In the 28-day oral 

rat study copper omadine caused similar effects at similar doses.

The committee concluded that if the required 90-day oral rat study shows neurologic effects at 

lower levels, then copper omadine cannot bridge to zinc (or sodium) omadine, and copper 

omadine will again fail the new chemical screen. Additionally, the following studies are 

required for copper omadine if the Agency decides the toxicology database should not be 

bridged:

90-day oral in rodent (870.3100) (a),

90-day inhalation in rat (870.3465) (a),

28-day dermal rat (870.3250),

90-day neurotoxicity in rat (870.6200) (a),

Prenatal developmental in rat (870.3700),

Prenatal developmental in rabbit (870.3700),

Reproduction and fertility effects (870.3800),

Developmental neurotoxicity (870.6300),

Immunotoxicity (870.7800)

Note: All 90-day subchronic studies in the rodent can be designed to simultaneously fulfill the 

requirements of the 90-day neurotoxicity study by using separate groups of animals for testing. 
−3−

ENVIRONMENTAL FATE - To bridge fate data between copper and zinc omadine, a 

full Adsorption/Desorption Study (835.1230) (soil column leaching too??? 835.1240) 

which shows the Kds for copper omadine in different soils and sediments is required. 

The paint leaching studies submitted appear to pass the new chemical screen, but will not 

be entered into review until after submission of the European test protocol used for these 

tests, along with a comparison of the European protocol with the U.S. protocol point for 

point. These studies still require full DER review for acceptability.

All other environmental fate data for copper and zinc omadine can be used to assess the 

environmental fate of copper omadine. However, the submitted studies still require 

Agency review for acceptability.

SCIENCE AREAS WHICH PASS SCREEN

PRODUCT CHEMISTRY - Copper omadine technical passes the new chemical screen. 

Study OPPTS GLN 830.1550, Chemical Identity, still requires Agency review for 

acceptability.

HUMAN EXPOSURE - Copper omadine passes the new chemical screen. Sufficient 

data exist for zinc omadine to perform a surrogate copper omadine human exposure 

assessment.

ECOTOXICITY - Copper omadine passes the new chemical screen. The copper 

omadine studies submitted are sufficiently similar in ecotoxicity to zinc omadine to allow 

bridging to existing zinc omadine ecotoxicity studies (see Appendix 1 attached). 

However, the copper omadine ecotoxicity studies still require Agency review for 

acceptability.

Note: The copper omadine nontarget plant toxicity study (MRID 45774320 - Tier I 

seedling emergence, 850.4100) has no zinc omadine counterpart and therefore was not 

useful for bridging purposes. 

Please relay any questions or comments to Rick Petrie @ petrie.rick@epa.gov, or (703) 

305-7358.