Common herbicide is harmful to fish

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A study carried out by the US Geological Survey (USGS) has found that one of the most commonly used herbicides in the world is harmful to fish.

The study was conducted by Donald Tillitt and a team of researchers at the Environmental Research Center in Columbia. The team exposed fathead minnows Pimephales promelas to levels of atrazine varying from 0-50 micrograms - all below the 'USEPA Office of Pesticides Aquatic Life Benchmark' of 65 micrograms per litre for chronic exposure of fish.  

They found normal reproductive cycling was disrupted by atrazine and fish did not spawn as much or as well when exposed to atrazine. Within 17-20 days of exposure those fish exposed to atrazine showed lower total egg production and abnormalities in the reproductive tissues of both males and females.

Donald Tillitt is quoted: "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".

Atrazine is one of the most commonly used herbicides in the world with a user-level world market worth over $400 million. It is used on most corn, sugarcane and sorghum acreage in the United States and on maize, forestry and grassland in the UK. UK usage has declined since a ban on its use on anything other than garden, home and cropped land was introduced.

Unfortunately, in the US atrazine is generally applied in the spring, resulting in highest concentrations when most fish in North America are attempting to reproduce.

This is not the first time that the chemical has made the news, with previous studies noting the effects on endocrine functions in salmon and the herbicide has also been linked to dramatic decline in frog populations due to reproductive effects, including the induction of hermaphroditism at very low levels.

Results of studies over the past 20 years have shown that throughout the Corn Belt streams and rivers atrazine concentrations are frequently found in levels at or above those found to affect fish reproduction.