DDT: Still poison after all these years
Next Monday is World Malaria Day, and DDT will surely be in the news. The usual parade of opinion pieces calling for a revival of DDT spraying to control malaria (as though it ever stopped) will be on display.
You'll likely also read that the World Health Organization (WHO) has raised fresh concerns about its safety, and you may even hear that the Stockholm Convention has endorsed its continued use. Let me try to explain what's going on.
In 2004, the Stockholm Convention — the international treaty that regulates the worst of the persistent chemicals, like PCBs and dioxins — banned the agricultural use of DDT globally. Countries were allowed to continue to use it for malaria control, provided they notify the Convention and follow WHO guidelines. The Convention also provides support to help countries transition away from DDT, and every few years it evaluates whether DDT is still needed. Government officials will do exactly that in Geneva next week when the Parties to the Convention meet.
The Stockholm Convention's DDT Expert Group already met in November to examine this question, and concluded that in certain (unnamed) "specific settings," DDT is still needed. Though underspecified, this is a reasonable enough conclusion, and the Group's report will very likely be rubber stamped in Geneva.
What the experts also said — DDT isn't used well & causes serious health harms
Malaria effects millions of people living in vastly different ecological and economic conditions. There are dozens of mosquito species that transmit the disease, each with unique behaviors, and different populations have different insecticide resistance profiles. It's inevitable that every now and then these factors conspire to make DDT the best choice of the many tools available to control malaria.
But the Expert Group found that most countries using DDT aren't using it very well. Most lack the capacity to ensure it isn't diverted to agriculture, and many are not testing whether mosquitoes are still susceptible to it. The quality of spray coverage is a problem, too. To be effective you've got spray the interior walls of most dwellings in a targetted area, otherwise you're just wasting money and polluting people's homes without doing anything to combat malaria. Spray coverage is often poor, according to the report.
Meanwhile, WHO just issued its long-awaited reevaluation of the health hazards of DDT. Among its findings:
- DDT puts kids at risk for delayed puberty and reproductive effects, genital birth defects, reduced growth, and "neurocognitive effects;"
- Moms exposed risk pre-term birth; and
- Spray workers risk reduced fertility and liver cancer.
There's nothing too surprising in there, if you've been paying attention to medical literature. What is surprising (and refreshing) is that it's the WHO that's saying this, since in the past their stance on DDT's health effects has been, shall we say, unclear.
Taken together, the WHO assessment and the Expert Group's report should raise red flags about the continued use of DDT. While the chemical still has a role to play, that role should very limited, given the risks involved and the difficulties inherent in using DDT safely and effectively. Unfortunately, it remains the "go to" intervention in some countries, and use increased by about 30% between 2007 and 2009, the two most recent years for which data is available.
Promoting DDT — a broader agenda
Superimposed on all of this is an ideological battle being waged mostly in the American media. I've blogged about it in the past, but others have followed this much more closely. (The excerpt from Merchants of Doubt by Naomi Oreskes and Erik Conway that we included in last Fall's PAN Magazine is probably the best primer).
In a nutshell, a handful of groups closely affiliated with right-wing think tanks are working overtime to stir up debate about DDT and malaria where there is actually widespread agreement. They view World Malaria Day as the perfect opportunity to promote their favorite myth: that a "ban" is preventing DDT from being used against malaria, resulting in millions of needless deaths. (See, for example, this, this, or this.) This story in turn brings into question EPA's action to control chemicals more broadly ("If EPA got it wrong on DDT, maybe all these other chemicals aren't so bad??")
In fact, there is no ban, DDT is rarely the best tool, and while malaria does remain a killer, it's not because of action EPA took back in the 1970s. But in demonizing Rachel Carson and deifying DDT, these interest groups — many of whom are also working to hamstring efforts to address climate change — hope to sow doubt about environmentalism and relieve the free market from the "burdensome" government interventions that protect you and me from pollution and other harms.
So this World Malaria Day, as the Stockholm Convention grapples with achieving the dual goals of eliminating both malaria and DDT, the free marketeers (as Oreskes and Conway call them) will endeavor to achieve their own goals, at the expense of those who desperately need safe and effective malaria control. PAN will be speaking out, and I'll be in Geneva advocating for increased investment in DDT alternatives at the Stockholm Convention meeting. To mark the day yourself, please consider making a donation to Nothing But Nets, or writing a letter to your newspaper sharing the truth about DDT.