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Regulatory Issues Associated with the
Development and Use of Biocide-(DCOIT)-
Containing Rubber
Thomas S. Ramotowski
NUWC Division Newport, Newport, RI, 02841, USA
19th International Congress on Marine Corrosion and Fouling
June 26, 2018 Melbourne, Florida, USA
UNCLASSIFIED – Distribution Statement A – Approved for Public Release; Distribution is Unlimited
Topics
• Background
> DCOIT Biocide in Rubber
• FIFRA
> Legal Definitions and Requirements
• The Regulatory Approval Process
> Modify Existing Label or Register a “Treated
Article”
> DCOIT “Blooming” from the Rubber
> ASTM D-6903
• Final Approval from US-EPA
• Summary and Acknowledgements
Protecting Elastomers from Marine
Biofouling: Problems & Opportunities
The options: paint/coat or include a biocide
Paints/coatings
typically do not work
well on rubbery
substrates.
Differences in modulus
lead to cracking and
peeling.
There are adhesion
and abrasion issues.
Biocide-based paints
and coatings only work
for short periods of
time due to limited
biocide storage
capacity (thickness
based reservoir effect).
4
Starting in 2013, NUWC Newport had been working to determine whether
DCOIT, a heavy metal free, isothiazolinone-based biocide that breaks down
rapidly once released into the marine environment, could be used to protect
critical elastomer-based parts from marine biofouling.
Rohm & Haas (now part of Dow Chemical) was awarded a
Green Chemistry Prize by the US-EPA in 1996 for the development of DCOIT.
4,5-dichloro-2-n-octyl-4-isothiazolin-3-one,
a.k.a. Vinyzene-Max, Kathon-287T and
DCOIT, a heavy-metal free marine biocide
made by the Dow Chemical Company
DCOIT: An Environmentally Friendly Marine Biocide
Half-life in seawater/sediment:
DCOIT = one hour/one day
TBTO = nine days/six-nine months
Bioaccumulation factors:
DCOIT = essentially none
TBTO = 10,000x
Max. Allowable Env. Conc.
DCOIT = 0.63 ppb
TBTO = 0.002 ppb
1% 6% 3% 0%
Neoprene test panels after 14 months exposure, FIT, Melbourne, Florida
EPDM Rubber test panels after 24 months exposure, FIT, Melbourne, Florida
EPDM Rubber test panel after
44 months of exposure
Narragansett Bay, Rhode Island
6%
Static Testing of Rubber Panels Containing DCOIT
12 months, TMSI, Singapore
0% 3% 6%
14 months, FIT, Melbourne, Florida, USA
0% 3% 6%
12 months, Pearl Harbor, Hawaii, USA
0% 3% 6%
Conathane EN-7 Polyurethane Test Panels
Containing DCOIT
7
VM Release Rate versus Time Plot
Red curve = fixed D; blue curve = 4x fixed DRubber thickness = 0.25”.
• Smaller (slower) D showsmore severe changes in VM release rate to thewater – a “D” of thatmagnitude cannot replenish the rubber/waterinterface fast enough to balance VM loss to the water.
• Dow suggests a level of3.0 μg/cm2-day is the minimum release rate needed to protect a surface from biofouling. That valuecould be used to estimateuseful service life for a VMprotected article.
FIFRA
Even though the intended targets of marine biocides are not insects,
fungi or rodents, such materials are regulated in the USA under the
Federal Insecticide, Fungicide and Rodenticide Act (FIFRA)
FIFRA Background
● FIFRA dates back to the Federal Insecticide Act of 1910.
● Originally enacted in 1947, codified under 7 USC chapter 6 § 136 et cet.
● Originally enforced by the Department of Agiculture, but in 1972 the
enforcing agency was changed to the Environmental Protection Agency
(EPA) with a change in emphasis to protect the environment and public
health.
● Under FIFRA, the US-EPA has the authority to regulate the marketing
of economic poisons in the USA. It can enter into cooperative agreements
with States to cooperate in the enforcement of FIFRA.
FIFRA: Legal Requirements
● FIFRA: Established the registration requirement for all pesticides
only after a period of data collection to determine:
> effectiveness (for intended use)
> appropriate dosage
> hazards
● Pesticide label holds users responsible for proper usage. If
restrictions are ignored, users are liable for any regulatory
consequences.
FIFRA: What Is a “Pest”?
● FIFRA: A “pest” is any insect, rodent, nematode, fungus, weed or any
other form of terrestrial or aquatic plant or animal life or virus,
bacterium or other micro-organism.
> Does not apply to the last three examples when present in/on
living people or animals.
FIFRA: What Is a “Pesticide”?
● FIFRA: A “pesticide” is any substance or mixture of substances
intended for preventing, destroying, expelling or mitigating any
pest.
> To obtain regulatory approval, applicant needs to prove
the active ingredient(s) will not cause unreasonable
adverse effects on human health and/or the environment.
FIFRA: The Difference between
R&D and Production
● FIFRA: No individual may sell, use, or distribute a pesticide not
registered with the US-EPA.
● One major exception: Experimental Use/Testing.
● If the pesticide is not registered, then it must be provided gratis
for experimental use/testing.
● Once the use changes from R&D to production, the pesticide may
be sold, but formal registration is required.
The EPA Options
By late 2014, testing had shown
that DCOIT could protect
rubbery substrates from marine
biofouling for significant lengths
of time. The Navy use switched
from R&D to production. That
meant we would have to get
regulatory approval from the
US-EPA.
EPA Options
● Modify an existing label (there were several because of Rohm & Haas/Dow
merger – e.g., “Vinyzene Max”; “Kathon 287T”; “Sea-Nine”)
> No existing label had > 0.2% DCOIT content; we needed up to 6%
> Easiest/fastest way to get approved because existing data from
Dow could be used.
> Requires cooperation/help from Dow Chemical
● View the DCOIT-containing rubber as a “treated article”
> Onus is on the Navy to provide required data
> Takes more time/could require additional testing
The EPA’s Concern About DCOIT
“Blooming” from the Rubber
Both US-EPA and Dow Chemical were
concerned about reports of the DCOIT
biocide “blooming” from the rubber
substrate the Navy was using.
DCOIT “Blooming” (Continued)
Sampling rubber boots for DCOIT FT-IR spectrum of DCOIT biocide
● FT-IR sampling of several old, large panels indicated the white material
on their surfaces was DCOIT biocide.
● Extensive sampling of Navy sensor rubber boots containing 6% DCOIT by
weight revealed no detectable trace of DCOIT biocide on their surfaces.
● Large panels were the first ones ever made with DCOIT – 12% by weight.
> exceeded solubility limit, hence blooming behavior
> 6% by weight or less of DCOIT is below solubility limit = no bloom
Rotating Cylinder Release Rate Data
(ASTM D-6903) for Biocides in Rubber
ASTM D-6903 method (developed for AF paints) had to be modified for our
rubber samples. Thin sheets of treated rubber were cut and glued to the
rotating cylinder.
US-EPA Registration Approval
On June 26, 2017, the US-EPA approved the Dow/Navy requested
label change for Vinyzene Max.
US-EPA Registration Approval (Continued)
This covers Federal requirements…now we need to satisfy State requirements!
Summary and Acknowledgements
● Marine biocides are regulated under FIFRA – the Federal Insecticide,
Fungicide and Rodenticide Act – by the US-EPA
> It does not matter if –
- the federal Government paid for the R&D
- the R&D was carried out by U.S. Government
scientists and engineers at a U.S. Government
facility for a U.S. Government need.
● An appropriate label must be developed for the biocide
> an existing label can be changed/updated
> approval as a “treated article”
> needed once biocide transitions from R&D to production
● Need to show effectiveness, dosage, and document hazards
● US Navy now has proper US-EPA registration for use of DCOIT biocide
in polymers up to 6% by weight; working on State specific approvals.
Special thanks to:
Elizabeth Haslbeck (NSWC Carderock)
David Laganella and Joanne Ryder (Dow Chemical Co.)
David Mercier, esquire (NUWC-NPT)
Questions?