© 2024 WLRN
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations
In South Florida, where the Everglades meet the bays, environmental challenges abound. Sea level rise threatens homes and real estate. Invasive species imperil native plants and animals. Pesticides reduce the risk of mosquito-borne diseases, but at what cost? WLRN's award-winning environment reporting strives to capture the color and complexity of human interaction with one of the most biodiverse areas of the planet.

Mosquito Spraying With Naled To Continue In South Florida, Despite Study Raising Health Concerns

Logan Riely
Miami Herald
A contractor for Miami-Dade County conducted mosquito control aerial spraying over Wynwood and the surrounding areas on Aug. 4, 2016.

Weeks after a study linked a pesticide used for mosquito control to slight motor delays in babies, officials in Miami-Dade and Palm Beach counties say they plan to use that pesticide in aerial spraying scheduled in the coming week.

But experts say more research needs to be conducted before officials can revise safety guidance for the chemical Naled.

The University of Michigan study released earlier this month investigated the effects of Naled and 23 other pesticides on about 200 babies in China. Researchers not associated with the study say the analysis of results is solid; but they and study researchers both say the sample size is small and it’s not clear how the Chinese infants were exposed to Naled or what quantities of pesticide they came into contact with.

“At this point we have some hints that make us concerned,” said Kim Harley, a reproductive epidemiologist and pesticide expert at the University of California-Berkeley. “But that’s one of the problems, that we’re trying to do regulation and risk reduction with a lot of holes in the science.”

Credit Kyle Holsten / WLRN
Protesters on Miami Beach in September 2016 opposed aerial spraying with the pesticide Naled as part of Miami-Dade County's effort to control mosquitoes that spread Zika.

  Harley did not work on the study, which she says is the first she’s seen on the effects of Naled in people who don’t work with it routinely, like agricultural workers and mosquito control technicians. The research looked at the correlation between Naled exposure and a range of neuromotor skills in babies aged six weeks and nine months; it found that nine-month-olds with prenatal Naled exposure had slight deficits in visual-motor and fine motor skills.

One of the study researchers, Monica Silver, said she doesn’t think officials should use this study alone as a basis for discontinuing Naled use. She pointed out her team had to hypothesize how exposure occurred (they think through food), and that they don't know whether the neuromotor delays are permanent.

“More work needs to be done,” she said. “I think this study certainly will bring about awareness and hopefully make other researchers aware that we need to be looking at this further.”

Mosquito control officials in the Keys and Broward, Miami-Dade and Palm Beach counties use Naled to target black salt marsh mosquitoes and several species of so-called “flooding” mosquitoes, which emerge after heavy rains.

Credit Kyle Holsten / WLRN
A 2016 file photo of planes used by Miami-Dade County contractors for aerial mosquito spraying.

WLRN spoke with representatives from all four South Florida mosquito control agencies. The officials say they use the pesticide in quantities approved by the Environmental Protection Agency: less than two tablespoons per acre in all four counties, and as little as an eighth of an ounce in Palm Beach County and half an ounce per acre in Broward. For now, the officials add, Naled is the best tool they have against adult mosquitoes that emerge from the Everglades, where pesticides can't be used.

Finally, the officials say they defer to the Florida’s Department of Agriculture and Consumer Services and the EPA for guidance on Naled. The Department of Agriculture did not respond to a request for confirmation that it had seen the University of Michigan study; however, a spokesman wrote that, “Naled is an EPA approved product.”

An EPA spokesman said no expert was immediately available for comment. A standard review of human health and ecological risks associated with Naled will take place before the end of 2017, according to the EPA website.

The EPA website also says people concerned about spraying or sensitivity to chemicals should stay indoors with the windows closed while spraying takes place. The website recommends storing outdoor items like toys and pet dishes, and cleaning items that aren’t able to be stored.

In Palm Beach County, aerial spraying with Naled is scheduled to take place after sundown on Saturday in populated areas west of Military Trail out to the Everglades.

Credit Miami-Dade County
Miami-Dade County
Areas in red show where aerial mosquito spraying is scheduled to take place Monday in Miami-Dade County.

  In Miami-Dade County, aerial spraying with Naled is scheduled between 12:01 a.m. and 5:30 a.m. on Monday. The spraying will cover Homestead, Florida City, Redland and West Kendall; it will also include an area east of U.S. 1 from Southwest 248th Street to the Rickenbacker Causeway, comprising parts of Cutler Bay, Palmetto Bay, Pinecrest, South Miami, Coral Gables, and Miami. Spokeswoman Gayle Love told the Miami Heraldthe county will be calling landline numbers in those areas on Saturday and Sunday to let residents know about the spraying.

Credit Broward County
Aerial spraying is scheduled to take place in the boxed area of Weston on Monday.

  In Broward County, aerial spraying is scheduled for the Weston area between 4 a.m. and 6:30 a.m. on Monday. The boundaries of the spray zone are: I-75 to the north, Griffin Road to the south, 165th Avenue to the east and 210th Avenue to the west. As of noon on Sunday, Broward County officials had not responded to a request to confirm what pesticide they plan to use.

This post has been updated to include information about aerial spraying scheduled for Monday in Weston.

July 6: This post has been updated after Broward county officials confirmed they use Naled to control salt marsh mosquitoes.

More On This Topic