[Federal Register Volume 89, Number 115 (Thursday, June 13, 2024)]
[Notices]
[Pages 50325-50326]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-13009]



[[Page 50325]]

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ENVIRONMENTAL PROTECTION AGENCY

[FRL-11976-01-OW]


Acute Aquatic Life Screening Values for 6PPD and 6PPD-Quinone in 
Freshwater

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is announcing 
the availability of Acute Freshwater Aquatic Life Screening Values for 
6PPD (N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) and its 
transformation product 6PPD-quinone (6PPD-q; N-(1,3-Dimethylbutyl)-N'-
phenyl-p-phenylenediamine quinone). The EPA developed these screening 
values as information under Clean Water Act (CWA) section 304(a)(2)(B) 
on factors for the protection of aquatic life. States and authorized 
Tribes may consider these screening values in their water quality 
protection programs. The screening values for acute exposures to 6PPD 
and 6PPD-q in freshwater are 8,900 nanograms per liter (ng/L) and 11 
ng/L, respectively. Consistent with CWA section 304(a)(2), the EPA 
expects to update these screening values from time to time as new 
information becomes available. This announcement is in accordance with 
CWA section 304(a)(3), which directs the EPA to publish information 
developed under 304(a)(2) in the Federal Register and make it available 
to States, authorized Tribes, and the public.

FOR FURTHER INFORMATION CONTACT: Amanda Jarvis, Health and Ecological 
Criteria Division, Office of Water (Mail Code 4304T), Environmental 
Protection Agency, 1200 Pennsylvania Avenue NW, Washington, DC 20460; 
telephone number: (202) 566-1163; email address: [email protected].

SUPPLEMENTARY INFORMATION:

I. What are 6PPD and 6PPD-quinone and how do they affect aquatic life?

    6PPD-quinone (6PPD-q) is a breakdown product of the rubber-tire 
antioxidant compound 6PPD (N-(1,3-Dimethylbutyl)-N'-phenyl-p-
phenylenediamine). Detections of 6PPD and 6PPD-q in waterways across 
the United States and elsewhere indicate that they are present in 
aquatic systems and may present a potential risk to aquatic organisms. 
Although ``urban stream syndrome'' or ``urban runoff mortality 
syndrome'' (URMS) was first reported in Puget Sound during monitoring 
of urban streams between 1999 and 2001, URMS was not linked to 6PPD-q 
until 2021 by Tian et al. (2021). URMS describes the death of adult 
salmon fish (particularly coho salmon) returning from the ocean to 
urban waterways and was first reported in Puget Sound (Washington, USA) 
during monitoring of urban streams between 1999 and 2001.

II. What are aquatic life screening values?

    The EPA derived these screening values in accordance with section 
304(a)(2) of the Clean Water Act (CWA) to provide States, authorized 
Tribes, and stakeholders with the best available information on the 
toxicity of 6PPD and 6PPD-q to aquatic organisms. They are distinct 
from national recommended ambient water quality criteria (AWQC) issued 
in accordance with the provisions of section 304(a)(1) of the CWA for 
protection of aquatic life from toxic chemicals. Empirical data are 
very limited for 6PPD and 6PPD-q and do not fulfill the EPA's data 
requirements for deriving national recommended AWQC. Further, much of 
the available data were developed using aquatic toxicity testing 
approaches that do not fully conform with EPA's 850 Ecological Effects 
Test Guidelines or other standard test guidelines, such as those of the 
American Society for Testing and Materials (ASTM) or the Organisation 
for Economic Co-operation and Development (OECD). These deviations from 
standard testing methods made the derived toxicity values and the 
derived screening values more uncertain than national recommended AWQC. 
These screening values are based solely on data and scientific 
judgments about the relationship between 6PPD and 6PPD-q concentrations 
and potential effects to aquatic organisms.

What are EPA's 6PPD and 6PPD-q aquatic life screening values in 
freshwater?

    The EPA's 6PPD and 6PPD-q aquatic life screening value documents 
provide a critical review of 6PPD and 6PPD-q toxicity data, quantify 
the toxicity of these chemicals to aquatic life based on available 
data, and provide separate acute screening values for 6PPD and 6PPD-q.
    Under CWA section 304(a)(2)(B), the EPA develops, from time to 
time, information ``on the factors necessary for the protection and 
propagation of shellfish, fish, and wildlife.'' The EPA developed the 
6PPD and 6PPD-q acute screening values (Table 1 of this document) to 
support protection of most freshwater aquatic communities. The EPA's 
acute screening values are the maximum concentrations of 6PPD and 6PPD-
q (individually, not in mixtures), with associated frequency and 
duration specifications, that are expected to support protection of 
aquatic life from acute effects in freshwaters based on currently 
available science (see Table 1 of this document). There were 
insufficient data for 6PPD and 6PPD-q to derive chronic screening 
values in freshwaters, and acute and chronic values in estuarine/marine 
waters.
    In accordance with CWA section 304(a)(2)(B), the acute freshwater 
screening values for 6PPD and 6PPD-q are provided only as information 
for States and authorized Tribes that they may consider for the 
protection of aquatic life as part of their water quality protection 
programs. The development of aquatic life screening values as 
information under CWA section 304(a)(2) does not impose legally binding 
requirements on the EPA or the regulated community. Further, the 
aquatic life screening values are not regulations and do not substitute 
for the CWA or the EPA's regulations.

 Table 1--Recommended Aquatic Life Acute Screening Values for Freshwater
                                 (ng/L)
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                                               6PPD           6PPD-q
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                                                   8,900              11
                                         -------------------------------
Duration................................              1 hour
Frequency...............................   Not to be exceeded more than
                                          once in three years on average
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[[Page 50326]]

Bruno Pigott,
Assistant Administrator.
[FR Doc. 2024-13009 Filed 6-12-24; 8:45 am]
BILLING CODE 6560-50-P