Rachel Carson must be turning in her grave. What would the Silent Spring author have said about the news that a revival of a widely-banned insecticide to fight the Zika virus mosquito is being considered in some quarters?

Microcephaly, a previously rare birth defect of the brain, is believed to be caused by the Zika virus, which carries devastating effects in the foetal stage but is otherwise mild in humans. In recent months the spread of Zika has taken on pandemic proportions.

Environmental health experts in the US say there is a good chance that such infectious diseases will become more common as the global climate warms. But will panic among sections of the conservative stronghold push policymakers to reach for DDT (dichloro­diphenyltrichloroethane)?

It was Carson’s account of ecological damage from widespread use of DDT since the 1940s that led to a public outcry and a US ban on the chemical for agricultural use since 1972. Yet certain agents in the US, primed by the industry-funded American Council on Science and Health, are now calling for the powerful insecticide to be ‘unleashed’ in an effort to stop the virus, which has sparked a public health emergency of international concern.

The health and environment risks of controversial calls for fumigation of Zika-stricken zones with DDT would have to be carefully weighed against the ravages of the virus.

Toxicity of DDT is cumulative. Using it on troops to prevent typhus and malaria in World War II was seen as a ‘calculated military gamble’, where the risk of poisoning was deemed less serious than the risk of exposure to those diseases at the time.

Mosquitoes evolved resistance to DDT after the chemical became widely used in post-war US agriculture, which was hailed as a miracle pesticide but then found to have a thinning effect on the eggshells of birds.

In 2006, the World Health Organisation reversed a longstanding policy against DDT by recommending its use indoors in regions where malaria is a major problem. Three years later, the organisation retracted its endorsement of the malaria clause and joined forces with the United Nations environmental programme to “completely phase out the chemical worldwide by 2020”.

In the light of the present global Zika alert, a director of the division of vector-borne disease at the US Centre for Disease Control and Prevention recently said that environmental concern about DDT “has to be reconsidered in the public health context”.

However, a spokesman for the agency insisted the solution would lie in working to control mosquitoes by educating the public, eliminating breeding sites and spraying to kill adult mosquitoes where there are outbreaks, although which sprays will be used has not yet been made public.

Environmental health experts in the US say there is a good chance that such infectious diseases will become more common as the global climate warms. But will panic among sections of the conservative stronghold push policymakers to reach for DDT?

Promoters of DDT argue that damage seen in wildlife could be blamed on widespread outdoor use but was less likely to result from small amounts on walls in urban areas.

Yet, health concerns around the effects of the insecticide on humans have continued to grow since Silent Spring was published in 1962.

Studies have uncovered links to increased rates of diabetes, developmental problems, miscarriages and certain cancers after exposure to the chemical. One study published in 2014 in the Journal of the American Medical Association, showed a link between Alzheimer’s and DDT.

Spraying clearly has its disadvantages. Efforts to prevent mosquitoes breeding in sprawling cities may not always be effective, and developing a vaccine against Zika could take years.

A biotech gap-filler hovers in the wings:

A genetically engineered mosquito and possible alternative to the use of toxic chemicals has already seen trials by Oxitec in the Brazilian city of Piracicaba. Male genetically modified (GM) mosquitoes have been released which pass a lethal gene to offspring, causing them to die before they can reach adulthood. Tests showed that a field population of Aedes aegypti, the primary carrier of Zika (and the more deadly Dengue fever virus) could be reduced by over 90 per cent.

But critics worry about the long-term effects of releasing GM organisms in the wild. Even Oxitec admits a “small possibility, as with any new technology, that sometime in the future there may be unforeseen consequences”.

Another approach, being tested in a Rio de Janeiro neighbourhood, is to infect mosquitoes with bacteria not normally threatening to them in the wild. This interferes with their ability to pick up and transmit viruses as it spreads through the mosquito population.

At the 2011 UN climate talks held in Durban, South Africa, climate change was noted to have influenced mosquitoes when breeding increased after heavier-than-usual rains in Mexico.

According to the Pesticide Action Network, many avid DDT promoters are also in the business of denying climate change. Last November, Bloomberg released a report that unearthed ‘America’s deep network’ of climate change deniers. It identified 4,556 individuals with overlapping network ties to 164 organisations responsible for efforts to downplay the threat of climate change in the US.

It all started in the 1970s as conservative US think-tanks, an intellectual counter-movement to socialism, turned their attention from the ‘red scare’ of Communism to the ‘green scare’ of environmentalism. They saw the green lobby as a threat to their aims of private property, free trade and global capitalism in a push for an anti-regulatory, free market agenda favoured by those close to industry.

The campaign to undermine public trust in climate science was fuelled by industrial, political and ideological interests inflated by sceptical bloggers and conservative media.

Spreading of doubt by climate denialists continued through the 1990s, culminating in a 1998 proposal by the American Petroleum Institute to recruit scientists to convince politicians and the media that climate science was too uncertain to warrant environmental regulation. The strategy to question and undercut prevailing scientific wisdom was not dissimilar to the organised denial of the hazards of smoking by tobacco companies.

In 1993, the US Environmental Protection Agency’s study on the cancer risks of passive smoking was attacked by Siegfried Frederick Singer, a climate sceptic known for having made a career of setting himself against mainstream scientific opinion.

A consultant for oil companies for many years, Singer has been a merchant of doubt, injecting himself in public debate about scientific issues.

In her book Shapers of the Great Debate on Conservation, Rachel White Scheuering put the spotlight on the man who spawned the Non-governmental International Panel on Climate Change (NIPCC), a 2004 parody of the Intergovernmental Panel on Climate Change. Scheuring demonstrates how Singer’s views concur with the economic interests of the companies that want to see a reduction in environmental regulations.

The so-called NIPCC came out with a report called ‘Nature, Not Human Activity’. Climate scientists from the National Aeronautics and Space Administration (NASA) dismissed it as “fabricated nonsense”. In 2013, another NIPCC report on climate change was floored by environmentalists for being “full of long-discredited claims”.

Closer to home, an obvious devotee of the NIPCC has recently surfaced in the letters column of the Times of Malta (‘Warming, extreme weather not linked’, February 2). Public relations specialist and climate sceptic Tom Harris, who has been linked to the Canadian energy industry, predictably hit out at an article by environmental management specialist Alan Pulis, a recent appointee to the Malta Environment and Resources Authority.

It is true that finding the most likely causes behind a particular extreme weather event can be challenging as a number of factors, including natural variability, may be involved. However, as the US environment authority confirms, scientists have been able to draw a connection between some types of extreme climate pattern and climate change.

The Malta Energy Efficiency and Renewable Energy Association plans to hold a forum on the implications of the Paris climate change conference on Malta and the Mediterranean.

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