FDA Says Genetically Engineered Mosquito Is Environmentally Safe

A genetically modified mosquito that’s been developed to help fight the spread of diseases like Zika and dengue has been given an early nod of approval from U.S. health regulators.

The U.S. Food and Drug Administration (FDA) agreed with an environmental assessment submitted by the biotech company Oxitec, that their genetically modified mosquitoes—which pass a lethal gene onto their offspring, thus eliminating a significant portion of the pests—would not have a significant impact on the environment. The company is currently releasing the mosquitoes in a city in Brazil, and has an application to do a similar project in the Florida Keys. As TIME previously reported, some people remain skeptical that the mosquitoes won’t have unintended consequences. The FDA’s report is preliminary, and available for public comment.

The announcement was released amid the ongoing Zika outbreak, which has been linked to the birth defect microcephaly. Scientists are still trying to determine that the virus definitely causes the birth defect, but it’s well established that the virus is spread by the Aedes aegypti mosquito. Oxitec’s modified mosquitoes carry one gene that causes the insects to overproduce a protein that ultimately kills them off in a couple days. The other gene causes the insects to be fluorescent under a microscope so scientists can assess how well the mosquitoes have infiltrated the wild population by collecting the eggs and looking at them in a lab.

The offspring of the modified mosquitoes do not reach adulthood, eventually lowering the number of Aedes aegypti overall. Since female mosquitoes are the ones that spread disease, Oxitec only releases males so that there’s no chance the modified versions could continue the chain of transmission.

Oxitec was founded in 2002 as a spin off from Oxford University. The American biotech company Intrexon Corporation bought Oxitec in 2015 for $160 million.

You can read more about Oxitec’s mosquito control approach here.