SACRAMENTO (AP) — California’s pesticide agency is conducting a review of popular insecticides because many are ending up in urban streams and killing tiny aquatic creatures. The review could lead to restrictions and even bans on many products used on lawns and gardens.

The chemicals, called pyrethroids, are man-made versions of natural compounds in chrysanthemum flowers. American consumers and exterminators have increasingly used them in recent years to replace dangerous insecticides already banned.

Last year, a scientist at the University of California at Berkeley, Donald Weston, reported pyrethroids are polluting streams in Northern California suburbs, wiping out crustaceans and insects vital to ecosystems.

Notices will be sent to manufacturers of about 600 pyrethroid products informing them that the state is reevaluating their use, said Mary-Ann Warmerdam, director of the state Department of Pesticide Regulation.

“This is a shot across the bow to the manufacturers that we found a reason for concern and you need to provide us with data to either eliminate the concern, reformulate your products or consider taking them off the market,” Warmerdam said.

Allan Noe, a spokesman for CropLife America, representing pesticide manufacturers, said the companies were unaware of California’s intentions but will cooperate with any requests.

“The valuable contributions that pyrethroids make through agricultural and urban uses are many and these benefits need to be considered,” Noe said.

Beyond lawn products, the compounds are prevalent in pet sprays and in insecticides used by exterminators and farmers. Many cities and counties spray a pyrethroid for mosquito control to prevent the spread of West Nile virus.

Use of pyrethroids by California farmers and exterminators has nearly tripled, growing from about 420,000 pounds in 1999 to 1.1 million pounds in 2004. State officials say consumer usage is probably double that.

Creeks in the Sacramento suburb of Roseville that contain high pyrethroid levels are devoid of tiny crustaceans called hyalella, while nearby streams with low levels are inhabited by them, according to Weston’s study, published in October. In lab tests, nearly all samples of the pesticide-tainted sediments from the creeks killed the creatures.

The shrimp-like amphipods live in bottom sediment and are important prey for small fish, frogs, salamanders and aquatic insects. Their presence is considered a sign of a healthy waterway.