Risks assessment: 750 million genetically engineered mosquitos for release in Florida

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Oxitec, a U.S.-owned company developing targeted biological insect control solutions, received final approval on August 18 2020 from the Florida Keys Mosquito Control Districts (FKMCD) Board of Commissioners to release its OX5034 Aedes aegypti mosquitos.  

The genetically modified mosquitos, set for release in 2021, are the second generation of the company’s GM mosquito species.  

Oxitec introduces two new genes into the mosquitos. The first is a male-selecting self-limiting gene, which prevents female mosquitos from reaching adulthood. This means only male, non-biting mosquitos survive. The second gene is a marker gene that activates fluorescence when exposed to certain ultraviolet (UV) frequencies. This allows scientists to identify mosquitos that are the byproduct of this genetic engineering and to monitor their offspring.  

This mosquito project appears to have undergone a rigorous and broad assessment prior to its approval, with a transparent consultation process and support from a large array of entities including universities, foundations and regulatory bodies. The assessment is legitimized by the participation of many actors, and the reliance upon hundreds of scientific studies. The U.S. Environmental Protection Agency (EPA) consolidated all of the data in their Memorandum  93167-EUP-E.

Oxitec’s website affirms that there are no direct  or indirect  harmful consequences resulting from the release of the GM mosquito. The studies have been conducted and analyzed by a wide variety of research groups, which include both public and privately funded organizations as well as an independent advisory board. This includes the EPA, the Florida Department of Environmental Protection, U.S. Centers for Disease Control and Prevention (CDC) and seven State of Florida agencies, including the Department of Health. The data and studies are overseen by FKMCD, the EPA and the Florida Department of Agriculture and Consumer Services (FDACS).

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A deeper look into the research, however, reveals a more complex and problematic view. Source studies related to the mosquito project are often funded by past or current Oxitec employees, as is the example in the study validating the environmental impact of the GM mosquitos for acquatic animals. 

As a result, Oxitec presented conclusions have been criticized as overreaching and unable to account for the broader impact of such a complex and highly uncertain program. 

For example, when accounting for the impact on the birds and mammals that feed on mosquitos, the assessment states that “the mosquito is likely to form only a small part of the bird diet.” The study makes this broad claim despite only referring to four species of birds, providing resource data on two species, with one of the studies indicating one genus actually relies on the Ae. Aegypti for half its diet. No data has been provided on the impact of these mosquitos on mammals. 
 

Further, the assessment does not address the potential impact on these ecosystems in the event of a total population loss, which is the ultimate aim of this program. 

Another problematic assessment is regarding the safety of the GM mosquito due to the non-nativity of the targeted mosquito species. The Ae. Aegypti mosquito originates from sub-Saharan Africa and is believed to have been introduced in the the Americas in the 17th century. This is used as a fact point to legitimize the assumption that this mosquito does not represent a significant portion of the diet of birds and mammals in Florida. The data provided to substantiate this belief is limited in scope and even demonstrates the importance of this mosquito in some food systems, particularly for the Eastern Bluebird.

Verifying the Data

There has been significant push-back from physicians and the scientific community concerning the legitimacy of Oxitec’s claims. This is particularly true for the claims of population suppression rates, efficacy, as well as risk assessment.

Cayman Islands Mosquito Research and Control Unit scientists challenge the claims of significant population suppression, stating that “To date all the measures recorded have shown no significant reduction in the abundance of Aedes aegypti in the release area.” They also assert through their research that there was also a “significant increase in the number of female mosquitos collected in the treatment area.” 

In fact, these mosquito populations may create a greater risk of spreading disease. According to the EPA documents, the spread of genes is likely given the increase of the survival rate of these mosquito larva to 50 percent. The EPA hasn’t considered the possibility of the mosquito evolving resistance to the killing mechanism, nor has it assessed any health risks involved with female biting GM mosquitos reaching adulthood.

This is of particular concern given the use of tetracycline, which is an antibacterial used as an antidote to the killing mechanism in female mosquitos. Oxitec has claimed that there is “no tetracycline in Florida” and that female biting mosquitos do not reach adulthood.

However, a leaked study from GM mosquito product manager Derric Nimmo has shown that survival rates of the female mosquitos increased 15  to 18 percent when exposed to tetracycline. Despite this, Oxitec maintains that tetracycline exposure is of no risk, and references this study to substantiate this claim. 9 of 11 contributors to this paper are Oxitec employees. 

The EPA has asserted that trials must be conducted away from areas where tetracycline is found – for example, in commercial citrus growing areas and sewage treatment plants. Incidentally, there are over 4000 citrus growers, cultivating around 437 000 acres of land in Florida. Also, the claim where GM mosquitos won’t have access to the tetracycline present in citrus growers conflicts with the CDC’s estimated range of Aedes aegypti mosquito.

The EPA affirms no determination of the allergic or toxic potential for the two new proteins. The assertion is that toxicity is not an issue, given the perceived unlikelihood that female mosquitos would survive. This is claimed despite problematic data on the survival rate of female biting GM mosquitos and potential problems brought forth relating to tetracycline exposure.

Specialists in the area of genetic engineering warn against the dangers of gene drive organisms, whereas the modifications are passed onto offspring and alters the entire population in the wild. Given the conditions of high uncertainty, experts have stated that the “assessments for regulatory approval of this genetically engineered insect fall short of several PPRAF (Procedurally Robust Risk Assessment Framework) under the principles of humility, procedural validity, inclusion, anticipation and reflexivity.”

A study has concluded that three years after the release of GM mosquitos in other areas, there is “clear evidence that portions of the transgenic strain genome have been incorporated into the target population.” The rare viable hybrid offspring have been sufficiently robust to breed in the population and demonstrate the presence of the GM markers in the wild. The available data clearly indicates the possibility and even likelihood of hybridizing wild mosquito populations, but Oxitec asserts this is an impossibility that does require more rigorous study or oversight. 

Strangely, there are no studies conducted on the possibility of female GM mosquitos reaching adulthood, and what the potential consequences could be.

Some experts and scientists have been vocal in their opposition of these GM mosquitos. Jayde Hanson, policy director for the International Centre for Technology Assessment and Centre for Food Safety, condemned this release, calling it a “Jurassic Park experiment.” Barry Wray, executive director of the Florida Keys Environmental Coalition, criticized the experiment for its risk profile and Oxitec’s profit motivation. 

Finally, the Florida Keys Mosquito Control District have declared that there is a small likelihood of contracting mosquito borne disease. As of August 2020, there are 47 active cases of Dengue Fever, the most statistically significant mosquito borne illness in the area. That represents 0.06% of the local population.  

All these conflicting perspectives leaves one to ponder, why? Opponents have questioned the financial motivations behind this program and the reasons for conducting this experiment, despite the clear risks involved. Why conduct a potentially dangerous experiment aimed at eradicating mosquito populations and illnesses, in an area with relatively few mosquito-borne diseases? Further, randomized field trials have found that other, less dangerous, non-GMO approaches have reduced mosquito-borne dengue by 77%

Given the concerns from informed citizens, physicians and scientists, this project requires significantly more third-party oversight, regulatory monitoring of the female survival rate and a greater environmental assessment for the legitimization of this project. As it stands, informed consent has not been achieved and the continuation of this process without the adaptation of expert recommendations would be dangerous and irresponsible.

Wiki Production Code: A0062

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