No doubt now: Atrazine herbicide hurts fish reproduction

Reston, Va. — Atrazine, one of the
most commonly used herbicides in the world, has been shown to
affect reproduction of fish, according to a new U.S. Geological
Survey study.

“Concentrations of atrazine commonly found in agricultural
streams and rivers caused reduced reproduction and spawning, as
well as tissue abnormalities in laboratory studies with fish,” said
USGS scientist Donald Tillitt, the lead author of the study
published in Aquatic Toxicology.

Atrazine, applied for decades to
farmland in the Susquehanna basin, is suspected of contributing to
the sharp decline in that Pennsylvania river’s smallmouth bass
 In the USGS study, fathead
minnows were exposed to atrazine at the service’s Columbia
Environmental Research Center in Columbia, Mo., and observed for
effects on egg production, tissue abnormalities and hormone
levels. Fish were exposed to concentrations ranging from zero to 50
micrograms per liter of atrazine for up to 30 days. All tested
levels of exposure are less than the USEPA Office of Pesticides
Aquatic Life Benchmark of 65 micrograms per liter for chronic
exposure of fish. Thus, substantial reproductive effects were
observed in this study at concentrations below the USEPA
water-quality guideline.
 Study results show that normal
reproductive cycling was disrupted by atrazine and fish did not
spawn as much or as well when exposed to atrazine. Researchers
found that total egg production was lower in all atrazine-exposed
fish, as compared to the non-exposed fish, within 17 to 20 days of
exposure. In addition, atrazine-exposed fish spawned less and there
were abnormalities in reproductive tissues of both males and
 Atrazine is one of the most
commonly used herbicides in the world and is used on most corn,
sugarcane and sorghum acreage in the United States. It is used to
stop pre- and post-emergence broadleaf and grassy weeds, and is
generally applied in the spring. Thus, noted Tillitt, atrazine
concentrations are greatest in streams during the spring, when most
fish in North America are attempting to reproduce.
 “The reproductive effects
observed in this study warrant further investigation and evaluation
of the potential risks posed by atrazine, particularly in wild
populations of fish from streams in agricultural areas with high
use of this herbicide,” said Tillitt.
 The results of this study add an
important ecological perspective to findings on atrazine
concentrations in streams reported by the USGS National
Water-Quality Assessment Program, as well as others, and highlights
the potential risks to aquatic species of this high-use chemical,
Tillitt said.
 “Results of studies over the past
20 years show that atrazine is the most frequently detected
pesticide in agricultural streams and rivers nationwide, and
particularly in the Corn Belt states,” according to Robert Gilliom,
Chief of the NAWQA Pesticide National Synthesis Project. “Atrazine
concentration data for Corn Belt streams and rivers show that
21-day average concentrations, similar to the exposure conditions
studied by Dr. Tillitt, exceeded levels found to affect fish
reproduction for most sites and years sampled.”
 Endocrine-active compounds are
associated with intersex and reproductive effects in fish. These
chemicals have the ability to adversely affect endocrine systems
and include some pesticides, PCBs, certain heavy metals, certain
household products, and many pharmaceuticals specifically designed
to interact with endocrine function.
 “Atrazine Reduces Reproduction in
Fathead Minnow (Pimephales promelas),” was authored by U.S.
Geological Survey scientists Donald Tillitt, Diana Papoulias,
Jeffrey Whyte, and Catherine Richter. It appeared in a recent
edition of Aquatic Toxicology.

Categories: Pennsylvania – Jeff Mulhollem

Leave a Reply

Your email address will not be published. Required fields are marked *