Did WHO change its DDT policy?

Last year I wrote about the inaccurate claims that the World Health Organization had reversed its policy on DDT when it had in fact supported its use all along.

A recent paper in Lancet Infectious Diseases 2007; 7:632-633 also concludes that there has been little real change. Authors Hans J Overgaarda and Michael G Angstreicha write:

In September, 2006, WHO alarmed many of us working toward a reduction in the use of toxic chemicals such as dichlorodiphenyltrichloroethane (DDT). In a press release, the organisation announced the promotion of DDT for indoor spraying against malaria mosquitoes.[1] After 30 years of gradually reduced focus on DDT, this appeared to be a sudden turnaround.

We, however, cannot see a real change in WHO policy. DDT was the main component of the WHO Global Malaria Eradication Program during the 1950-60s. The programme ended in 1969 following evidence of DDT resistance in mosquitoes and increased public concern about adverse health and environmental effects. From 1970 onwards, many countries banned the agricultural use of DDT. However, in 1971, an executive WHO board maintained that indoor spraying of DDT was still WHO policy.[2] During the following decades, the WHO Expert Committee on Malaria continued to order indoor spraying of DDT for malaria vector control, provided that the targeted mosquito species were vulnerable to the insecticide. In the 1990s, several reports linked DDT to human cancers[3] and [4] and the insecticide was found in breast milk;[5] however, WHO continued to promote DDT use.

The pro-DDT community, which includes the organisation Africa Fighting Malaria, a US senator, Fox News, and Junkscience.com, argues strongly in favour of DDT as a panacea for the world's malaria problems. This community's arguments often refer to South Africa, which replaced DDT with deltamethrin in 1996. After 5 years of deltamethrin use, annual malaria cases increased substantially--a consequence of insecticide resistance in mosquito species entering from neighbouring Mozambique.[6] These mosquitoes were still susceptible to DDT; thus, the government resumed indoor spraying with DDT and promoted more effective antimalarial drugs. As a result, the number of malaria cases decreased.

As shown by WHO's Global Malaria Eradication Program, malaria control requires an integrated approach. An arsenal of interventions are needed ranging from timely and effective habitat and vector control, prompt and rapid diagnosis and treatment, reliable distribution of bednets, drugs, and prophylactics, public awareness campaigns, insect-parasite research, and interministerial cooperation to improve people's sanitation and living conditions.


In 2002, Sri Lanka started a UN-sponsored pilot project with the objective of developing a participatory integrated approach to reduce pesticide use and vector-borne disease through established Farmer Field Schools. By combining IPM and IVM (IPVM), control of both agricultural pests and disease vectors were achieved simultaneously. An emphasis on community participation responded to farmers' priorities: first food and money, then health.

In December, 2006, an international workshop convened by the WHO Regional Office for Southeast Asia recommended that member states declare IPM, IVM, and IPVM as preferred strategies.

The IPVM experience in Sri Lanka will be expanded to other countries in southeast Asia and the Pacific. The Norwegian agricultural and environmental research institute, Bioforsk, will be working with UN organisations and project countries to demonstrate the IPVM approach as a sustainable alternative to DDT and other toxic chemicals.7

In conclusion, we emphasise the importance of an integrated approach to vector management. Silver-bullet solutions such as DDT alone are not the answer. DDT is still an important temporary tool to control malaria under difficult conditions, but its use should strictly follow WHO guidelines. There are science-based reasons for DDT being on the "dirty dozen" list of the Stockholm Convention on Persistent Organic Pollutants and alternatives are needed. Our responsibility to future generations demands choosing safe and sustainable alternatives in our present activities.


More like this

One hesitates to jump up and shout "devastating blow", etc., etc., just to avoid keeping unsavory company -- but this does appear to be a direct hit on the "de facto ban" hooey.

Tim -- could you supply the references?

>[1] WHO. [WHO gives indoor use of DDT a clean bill of health for controlling malaria. Sept 15, 2006.](http://www.who.int/mediacentre/news/releases/2006/pr50/en/index.html) (accessed Aug 22, 2007).

>[2] WHO. The place of DDT in operations against malaria and other vector-borne diseases. In: Executive Board 47th Session, 19-29 January 1971, part II. Report on the proposed programme and budget estimates for 1972. Geneva: World Health Organization, 1971 (Official Records of the World Health Organization No. 190: 176-182).

>[3] Garabrant DH, Held J, Langholz B, Peters JM, Mack TM. DDT and related compounds and risk of pancreatic cancer. J Natl Cancer Inst 1992; 84: 764-71.

>[4] Wolff MS, Toniolo PG, Lee EW, Rivera M, Dubin N. Blood levels of
organochlorine residues and risk of breast cancer. J Natl Cancer Inst 1993; 85: 648-52.

>[5] Bouwman H, Cooppan RM, Reinecke AJ, Becker PJ. Levels of DDT and
metabolites in breast milk from Kwa-Zulu mothers after DDT application for malaria control. Bull World Health Organ 1990; 68: 761-68.

>[6] Hargreaves K, Koekemoer LL, Brooke BD, Hunt RH, Mthembu J, Coetzee M. Anopheles funestus resistant to pyrethroid insecticides in South Africa. Med Vet Entomol 2000; 14: 181-89.

>[7] Bioforsk. [Division of plant health and plant protection: a new project in Asia--integrated pest control against malaria. July 9, 2007.](http://www.bioforsk.no/ViewNews.aspx?view=1&id=2861&viewLanguage=English)
(accessed Aug 22, 2007).

Some Facts:

Rachel Carson Silent Spring (1962)

EPA bans DDT for agricultural use (1970)

Tanzania blanket bans DDT (1992)

FAO obsolete pesticide programme in Tanzania (1997)

Tanzania lifts DDT ban (2006)

WHO always endorsed DDT spraying.

Rachel Carson was wrong.

By Hans Erren (not verified) on 28 Sep 2007 #permalink


Tanzania blanket bans DDT (1992)

That's not quite true, Hans. It was already banned for agricultural use, but that ban wasn't preventing massive quantities of DDT being used agriculturally.


"DDT has been banned for use in agriculture and thus is not registered. At present there is no provision to regulate DDT use in public health."

Even following the delicensing, Tanzanian farmers were still using DDT agriculturally:


Rachel Carson was wrong.

In what respect?

By Robin Levett (not verified) on 28 Sep 2007 #permalink

Hans Erren, who wants us to believe he's a reasonably bright, rational fellow with no political axes to grind, posts the following idiocy:

Rachel Carson Silent Spring (1962)

EPA bans DDT for agricultural use (1970)

Fair enough

WHO always endorsed DDT spraying.

WHO endorses DDT spraying to check malaria, not for broadcast applications on ag crops.

Gee! Hans is (indirectly) lying!

Rachel Carson was wrong.

Rachel Carson recognized the usefulness of DDT for combating disease vectors, and in Silent Spring didn't suggest a 100% ban.

Rachael Carson: widespread ag use was very very harmful. Targetted use for disease vector control makes sense.

You say she was wrong.

This means, presumably, that we should be spraying the shit out of the countryside with DDT for ag use?

During my stay in Tanzania (1997-2000), I never came across any documents promoting the use of DDT for inhouse spraying.
The only antimalarial insecticide that was promoted was DEET-impregnated mosquitonets.
So even if there was a WHO DDT policy, nobody knew about it, and it certainly was not promoted.

Furthermore, I assisted the FAO Obsolete Pesticide programme with creating maps for the final report, so the FAO position is clear about this.

Who to blame for "misinterpreting" poor Rachel Carson?
Who to blame for deluding me?

Why was Rachel Carson wrong? The birds are still singing.

from wiki (FWIW)
Since the appointment of Arata Kochi as head of its anti-malaria division, the WHO has shifted its position in this controversy, from primary reliance on bed-nets to a policy more favorable to DDT. Until an announcement made on 16 September 2006, the policy had recommended indoor spraying of insecticides in areas of seasonal or episodic transmission of malaria, but a new policy also advocates it where continuous, intense transmission of the disease causes the most deaths.[55] In 2007, the WHO clarified its position, saying it is "very much concerned with health consequences from use of DDT" and reaffirmed its commitment to phasing out the use of DDT.[56]

By Hans Erren (not verified) on 30 Sep 2007 #permalink

A few more facts, Hans:

  • DDT resistance in malaria-carrying mosquitoes was observed as early as 1951, in Greece. By the end of 1953, vectors were resistant in Lebanon, Iran, Saudi Arabia and Indonesia. WHO was aware of DDT resistance, and changing its antimalarial strategy, ten years before the publication of Silent Spring.
  • DDT use in the US began to decline in 1959, as cotton farmers started to abandon an insecticide that had become ineffective against the boll weevil and bollworm. That's still three years before Silent Spring, for those keeping track.
  • When Silent Spring was published, Rachel Carson discussed the development of insecticide resistance in disease vectors, and quoted Holland's Dr. Briejér approvingly:

    It is more sensible in some cases to take a small amount of damage in preference to having none for a time but paying for it in the long run by losing the very means of fighting. (pp. 274-5)

    Rachel Carson was not opposed to any use of insecticides for disease vector control; she just wanted a strategy that worked.

  • When EPA suspended registration of DDT in the US for nearly all agricultural uses, public health applications were explicitly permitted, and the order went out of its way to state that the ban would not apply to exports:

    It should be emphasized that these hearings have never involved the use of DDT by other nations in their health control programs. As we said in our DDT Statement of March, 1971, "this Agency will not presume to regulate the felt necessities of other countries."

The ban on agricultural use (in 1972, not 1970) was, if anything, belated. It is impossible to know for sure, but it seems very likely that an earlier switch to integrated pest management, and a change in policy to reserve DDT for disease vector control, would have resulted in a much greater reduction in cases of malaria during the 1950s and 1960s. In other words, Rachel Carson was right on all counts. Hope this helps.

Well, as Rachel Carson said, the birds would not be singing if widespread agricultural use of DDT persisted. It did not. The birds are singing. So, Hans, how was Rachel Carson wrong?

PS. Please don't prevaricate

Why was Rachel Carson wrong? The birds are still singing.

Well, in the United States brown pelicans quit splash-diving, bald eagles quit feeding on dead or dying waterfowl in winter in the lower 48, peregrine falcons quit preying on shorebirds and waterfowl, osprey gave up fishing ...

And then the DDT ban went into effect.

And they have all come back as a result.