DDT: A Curse or Blessing In Disguise

By: Jennifer Pearson

From Bisphenol A (BPA) in plastics to the use of mercury in immunizations, the scientific community is certainly accustomed to public fear, not scientific evidence, being the primary reason for banning chemicals in various everyday products. One chemical subject to such scrutiny is dichlorodiphenyltrichloroethane, or DDT. Today, with only China and India producing DDT and only a handful more using it, DDT acts as a symbol for the dangers that can be incurred when man attempts to alter nature. However, DDT has not always had such a reputation.

Discovered in the late 1930s, DDT was quickly acknowledged as a more or less miracle insecticide used abundantly to treat typhus and malaria. Throughout the 1940s, DDT had a profound impact on the state of public health across nations. However, many changes were made in 1962, when Rachel Carson published “Silent Spring,” claiming that DDT caused a plethora of adverse environmental effects that not only disrupted the health of mosquitoes or lice but also that of the entire food chain. Naturally, it would be prudent to question the credibility of Carson's claims. After years of research into DDT, it has been found that DDT can pose a danger to both our health and environment. In some research, DDT has been correlated to the pathogenesis of diabetes, cancers, and endocrine diseases that can even be passed on through breast milk, posing a particular risk for the developing world. Further confirming Carson's claims is DDT's ability to disturb entire ecosystems. Given these issues, is it justified to advocate for the increased use of a dangerous chemical in developing nations? 

I would to argue yes. First, DDT is a highly cost effective option. DDT has been noted to possess the lowest cost per person protected compared to other interventions, including Icon, Ficam and Propxur. Cheap health intervention methods are not that easy to come by and typically, effective intervention methods can have crippling logistical and distribution issues. Nonetheless, the cost should never be the sole determining factor in the approval of healthcare interventions. In the case of DDT, its potency is another, if not more important, factor that provides support for its safe use. Before DDT, pyrethrum was used in anti-malarial prevention. However, pyrethrum required multiple administrations as it only killed those mosquitoes present during the spray. Alternatively, with DDT, one spray would kill all mosquitoes in the vicinity for an entire 6 month period. For that reason, if we are able to provide an intervention method that is extremely effective without placing significant financial burden on the healthcare system, one must seriously consider the feasibility of such an option.

While such a potent substance do possess extremely adverse side effects, current proposals have made provisions in the use of DDT such as discouraging continuous spraying of the insecticide. If a country elects to use DDT as an intervention method, it is recommended that DDT is used only through indoor residual spraying (IRS). The World Health Organization also includes IRS as a component of malarial prevention strategies, alongside environmental management and improved infrastructure development. Due to the presence of pathogen resistance to DDT in various parts of Africa, monitoring such resistance has as become an essential aspect of current DDT intervention strategies. When DDT resistance is found, spraying in those regions ceases and alternative (and less effective) malarial intervention methods are implemented. Resistance monitoring, therefore, limits the use of DDT to only those regions which are non-resistant and prevents unnecessary spraying in resistant areas.

Despite the fact that DDT spraying is more conservative in today’s intervention methods, many environmentalists and advocates against the use of DDT actually argue that any use of DDT is greatly detrimental to both human health and the environment yet some literature suggests otherwise. Studies assessing the long term effects of DDT found “no significant excess morbidity” in spraymen who worked in previous eradication programs. If anyone is to be prone to DDT’s toxic effects, it would surely be those who work with DDT directly and whose exposure to the pesticide is the greatest. DDT has most infamously been linked to the cause of breast cancer through its weak estrogenic activity. However, recent conclusions have suggested that there is no strong evidence to support these claims nor has DDT ever been successfully linked to adverse effects on reproductive health. 

No one has to be told about the great impact malaria has had on health in Africa. If using one cost-effective chemical responsibly can provide a significant reduction in the number of deaths due to malaria, one would think that this intervention would be employed with great gusto. Those against the use of DDT must bare in mind that until a more sustainable alternative is found, DDT remains an important and highly effective component of today’s malarial prevention strategies. It is not this article’s contention that DDT is without its problems, rather when used with caution, DDT’s benefits greatly outweigh the potential threats it poses. In judgment of practices that weigh so heavily on matters of life and death, we must avoid summing the issue into a simple binary of yes or no. We must carefully weigh the risks against the benefits in order to take the most responsible and ethical route to prevent and treat such a widespread disease. 

References

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(4) Sadasivaiah S, Tozan Y, Breman JG. Dichlorodiphenyltrichloroethane (DDT) for indoor residual spraying in Africa: how can it be used for malaria control? Am J Trop Med Hyg 2007 Dec;77(6 Suppl):249-263.

(5) Schapira A. DDT: a polluted debate in malaria control. Lancet 2006 Dec 16;368(9553):2111-2113.

(6) Schapira A. DDT still has a role in the fight against malaria. Nature 2004 Nov 25;432(7016):439.

(7) http://www.npr.org/templates/story/story.php?storyId=6083944