Final National Recommended Ambient Water Quality 

Criteria for Carbaryl - 2012

Summary

EPA has published in the Federal Register final

national recommended ambient water quality 

criteria (AWQC) for the protection of aquatic 

life from the potential effects of carbaryl.

Carbaryl (Sevin®) is a pesticide used to control 

insects, slugs and snails and to thin fruit in 

orchards. It can enter water bodies through 

runoff and potentially pose risks to aquatic life.

Carbaryl is the second most frequently found 

insecticide in water, with detections in 

approximately half of monitored urban streams. 

The criteria document will help states, 

territories, and authorized tribes add to their 

water quality standards a concentration level for 

carbaryl, at or below which aquatic organisms 

will be protected. EPA's national recommended 

final acute and chronic AWQC for protecting 

freshwater organisms from potential effects of 

carbaryl is 2.1 micrograms per liter. To protect 

estuarine and marine organisms from potential 

acute effects of carbaryl, EPA is recommending 

a final acute AWQC of 1.6 micrograms per liter. 

At the present time, there are insufficient data to 

calculate a chronic AWQC for estuarine and 

marine organisms.

What are aquatic life criteria?

Aquatic life ambient water quality criteria are 

numeric values that protect aquatic life from the 

harmful effects of pollutants in surface waters. 

Under section 304(a) of the Clean Water Act, 

EPA is required to develop and publish criteria 

for water quality that reflects the "latest 

scientific knowledge." These water quality 

criteria are based solely on data and scientific 

judgments about the relationship between 

pollutant concentrations and potential 

environmental and human health effects.

EPA’s national recommended water quality 

criteria provide guidance to states, territories and 

authorized tribes in adopting water quality 

criteria that meet the requirements of the Clean 

Water Act. They are not regulations themselves 

and do not impose legally binding requirements 

on EPA, states, territories, authorized tribes or 

the public. 

What is carbaryl?

Carbaryl is a member of the N-methyl carbamate 

class of pesticides, which share a common 

mechanism of toxicity by affecting the nervous 

system in animals via acetyl cholinesterase 

inhibition. Carbaryl also affects plant 

development and is used to thin fruit in orchards. 

Carbaryl has many trade names, but is most 

commonly known as Sevin®. It is registered in 

the U.S. for controlling insect pests on more 

than 115 agricultural and other sites, including 

home and garden uses. 

In a 2006 report, the US Geological Survey 

National Water Quality Assessment Program 

reported carbaryl as the second most frequently 

detected insecticide in water. It has been found 

in approximately 50 percent of monitored urban 

streams. EPA previously developed national 

recommended ambient water quality criteria for 

the other three most frequently detected

registered insecticides in U.S. waters

(chloropyrifos, diazinon and malathion).

Carbaryl was re-evaluated by EPA and found to 

be eligible for reregistration in 2007. Carbaryl is 

currently undergoing registration review, which

is scheduled to be completed in 2016.

How were these water quality criteria for

carbaryl derived?

EPA derived these aquatic life water quality 

criteria for carbaryl using EPA’s 1985 

Guidelines for Deriving Numerical National 

Water Quality Criteria for the Protection of 

Aquatic Organisms and Their Uses. The 

Office of Water EPA - 820-F-12-004

4304T May 2012
carbaryl criteria document has a new format that 

follows EPA’s Guidelines for Ecological Risk 

Assessment (EPA/630/R-95/002F). Toxicity data 

for developing the water quality criteria were

obtained from peer-reviewed open literature 

studies and from studies submitted to EPA for 

the registration and reregistration of carbaryl. 

To ensure the quality of the information, EPA's 

Office of Water worked closely with the Office 

of Pesticide Programs and subjected the toxicity 

data and other information on the effects of 

carbaryl to both internal and external peer 

review.

Specifically, what are the final aquatic life

criteria values for carbaryl?

Based on available studies, EPA's national 

recommended final acute and chronic ambient 

water quality criteria for protecting freshwater 

aquatic animals from the potential effects of 

carbaryl is 2.1 micrograms per liter (Table 1).

This means that freshwater aquatic organisms 

would have an appropriate level of protection if 

the one-hour average concentration and the fourday average concentration of carbaryl does not 

exceed 2.1 μg/L more than once every three 

years on average.

For the protection of estuarine and marine 

organisms, EPA is recommending an acute 

ambient water quality criterion of 1.6 

micrograms per liter (Table 1). In this case, 

estuarine/marine aquatic animals would have an 

appropriate level of protection if the one-hour 

average concentration does not exceed 1.6 μg/L 

more than once every three years on average 

(except where a locally important species may 

be more sensitive). At the present time, there 

are insufficient data to calculate a chronic 

estuarine and marine criterion.

Table 1. Summary of Aquatic Life Criteria for 

Carbaryl

Acute Chronic

Freshwater 2.1 μg/L 2.1 μg/L

Estuarine/marine 1.6 μg/L N/A

N/A – not available

How to View the Criteria Document

EPA has established an official public docket for 

this action under Docket ID No. EPA-HQ-OW2012-0787, accessed at www.regulations.gov.

You may also download the document from 

http://water.epa.gov/scitech/swguidance/standar

ds/criteria/aqlife/index.cfm.

For More Information

Contact: Diana Eignor by telephone at (202) 

566-1143, or by email at eignor.diana@epa.gov, 

or by mail at U.S. EPA, Health and Ecological 

Criteria Division (4304T), 1200 Pennsylvania 

Ave., N.W., Washington, D.C. 20460.