Posted 11 March 2016
By Michael Mezher
The US Food and Drug Administration (FDA) on Friday said that a proposed trial to release genetically engineered mosquitoes in Key Haven, FL poses no significant threat to the environment.
The mosquitoes, referred to as OX513A, are a modified strain of the Aedes aegypti mosquito developed by the UK-based Oxitec Ltd.
The mosquitoes are modified so that most of their offspring die before reaching maturity, and have been altered to include a red fluorescent marker to make them easier to identify.
So far, Oxitec's mosquitoes have been released in field trials in the Cayman Islands, Malaysia, Panama and Brazil, and are being evaluated as a high-tech option in the fight against the Zika Virus and other mosquito-borne diseases.
Last week, FDA's Acting Chief Scientist Dr. Lucia Borio told Congress: "It's very important for us to go through the process and include the public comment … we need to give the public an opportunity to comment on the environmental assessment, given the significant attention that this novel technology has generated, especially in the communities where the proposed sites [are]."
According to Oxitec's proposal, the company plans to conduct a controlled release of its male OX513A mosquitos in Key Haven, FL, in cooperation with the local mosquito control district, with the goal of demonstrating effectiveness in suppressing the Aedes aegypti population compared to areas where the mosquito is not being released.
If the trial is approved, it would mark the first time a genetically modified insect is released in the US. However, if the trial is approved, it could still be years before OX513A mosquitoes are approved by FDA as a new animal drug.
FDA took three years to approve AquaBounty's genetically engineered salmon after reviewing the company's draft environmental assessment in 2012. The agency also faced significant public and congressional backlash after approving the salmon for human consumption in late 2015.
FDA's Preliminary Findings
In reviewing Oxitex's proposal, FDA says it weighed the potential risk of exposure to the OX513A mosquito against the threat of dengue and other mosquito-borne diseases.
To reach its preliminary findings, FDA and experts from the Centers for Disease Control and Prevention (CDC) and Environmental Protection Agency (EPA) reviewed data provided by Oxitec, as well as a joint FDA-CDC inspection of the company's hatching facility.
Based on its review, FDA says the risk posed to humans by exposure to male OX513A mosquitoes is "negligible," and because the male mosquitoes do not bite, the agency does not expect any increase in disease transmission due to the release.
The agency also reviewed data to determine whether female OX513A mosquitoes could expose humans to the two modified proteins the mosquito possesses. FDA says the risk of human exposure to these proteins is "highly unlikely," and that there is "no convincing evidence" that the proteins would have toxic or allergenic effects in humans.
According to FDA, the risk of disease transmission by these mosquitoes is further reduced as the mosquitoes are bred in the UK, where local transmission of diseases such as dengue and chikungunya does not occur. As a precaution, blood used to feed the breeding population is sourced from healthy animals that undergo screening for various viruses and bacteria.
FDA says the likelihood for damage to the environment caused by the release of OX513A mosquitoes to be "largely negligible."
The agency says it was unable to identify any parasites or decomposers, such as bacterial or fungi, that only infect Aedes aegypti mosquitoes.
Additionally, there is only one endangered species that lives within range of the proposed release site, the Stock Island Tree Snail. FDA says that Oxitec's proposed trial is not expected to have any effect on the snail's habitat and should not threaten its existence.
FDA also says that Oxitec's hatching facility poses no threat to the environment, and has "multiple redundant levels of physical containment," which were verified during the agency's inspection.
Oxitec Environmental Assessment
FDA Preliminary Findings