Correspondence

Document Sample
Correspondence Powered By Docstoc
					Indian J Med Res 126, December 2007, pp 584-586




Correspondence
                               Resurrection of DDT : need for caution



Sir,                                                               unquestionable11. But DDT is a chemical tool to control
                                                                   vector borne diseases in general and malaria in
     Apropos the editorial on resurrection of DDT by
                                                                   particular. DDT also needs to be used with caution, it
Dash et al 1. The authors have highlighted the desirable
                                                                   may cause harm to human health rather than protecting
attributes and unquestionable utility of DDT in vector-
                                                                   them from malaria and other vector borne diseases.
borne disease control, particularly against malaria which
                                                                   High incidence of undescended testes, poor sperm
is emerging and resurging in different parts of the world
                                                                   quality, miscarriage, reduced breast milk production,
including India. The unwarranted misuse and overuse
                                                                   neurological effects, elevated risk of breast cancer,
of DDT in agriculture and public health during the DDT
                                                                   other types of cancer and undesirable impacts on the
era and detection of residue of DDT in human breast
                                                                   nervous system and liver have been reported12,13. So,
milk, plants and animals had made the world look at
                                                                   it would be desirable if the use is confined only to
DDT with fear2-6. This fear was further aggravated by
                                                                   public health particularly for indoor residual spray
environmentalists who agitated against DDT altogether.
                                                                   (IRS) especially during rotation of insecticides and
Further, the Environmental Protection Agency (EPA)
                                                                   management of resistance in vector borne disease
has listed DDT as a “probable human carcinogen”7.
                                                                   control programmes. Further, DDT is not the only
    The editorial falls short of the reasons for such a            insecticide used for IRS and so, alternative insecticides
resurrection of DDT. It seems to imply either most of              may also be considered for use as and when required14.
the malaria vectors have developed resistance to all the           Unilateral reliance of DDT in malaria vector control
insecticides currently used in public health or none of            in the long run may lead to greater danger of human
the insecticides in use today is as potential as DDT.              exposure and hastening the development of resistant
This resurrection might be due to its affordable cost              mosquito population. Even in many malaria endemic
and appreciable efficacy over other insecticides used              African countries, there are several instances that
in public health at present2. Though a maximum of                  certain social and cultural factors hinder the
10, 000 metric tones of DDT per annum for the control of           effectiveness of DDT sprayed indoors15. Preventive
malaria and kala-azar is permitted in India8, there have           measures to watch out the leakage of DDT into the
been very few evidences of the dramatic decline of malaria         environment or agriculture should also be
cases. Further, it has been reported that malaria vectors          strengthened. More effective and safer alternative
are still resistant to DDT in certain places/States in             approaches for malaria control should be envisaged
India8-10. The authors have not made any suggestions               as also bioenvironmental control measures through
on what India should do under such circumstances.                  multi-sectoral collaboration and community
                                                                   participation.
    The emergence of resistance by many malaria
vectors against most of the insecticides including the
synthetic pyrethroids used in public health and their                                                   N. Sivagnaname
alarming cost have made the entomologists and the                                     Division of Applied Field Research
public health specialists to reconsider the use of DDT                           Vector Control Research Centre (ICMR)
but with care. The inevitable role of DDT to bring                                             Puducherry 605006, India
down malaria cases in South African countries is                                    email: sivagnaname777@yahoo.com

                                                             584
                               SIVAGNANAME : RESURRECTION OF DDT : NEED FOR CAUTION                                         585

                          References                                  Authors' Response
1.   Dash AP, Raghavendra K, Pillai MKK. Resurrection of DDT
     : A critical appraisal. Indian J Med Res 2007; 126 : 1-3.
                                                                      Sir,
2.   WHO backs DDT for malaria control? Available from: http:/            N. Sivagnaname1 is probably unable to understand
     /news.bbc.co.uk//2/hi/science/nature/5350068.stm, accessed       the genesis of our editorial2 due to his lack of expertise
     on October 22, 2007.                                             and familiarity of the enormous volume of scientific
3.   Garabrant DH, Held J, Langholz B, Peters JM, Mack TM.            data available on global malaria control and well
     DTT and related compounds and risk of pancreatic cancer. J       structured malaria control strategies successfully
     Natl Cancer Inst 1992, 84 :764–71.                               practised in India.
4.   Wolff MS, Toniolo PG, Lee EW, Rivera M, Dubin N. Blood
                                                                           Resurrection of DDT was not our decision and it
     levels of organochlorine residues and risk of breast cancer. J
     Natl Cancer Inst 1993, 85 :648–52.                               was done by the WHO as it lifted the ban of DDT
                                                                      deployment in malaria control, a consequence of the
5.   Bouwman H, Schutte CH. Levels of DDT and metabolites in
     breast milk from Kwa-Zulu mothers after DDT application for
                                                                      failure of its Roll Back Malaria (RBM) initiative
     malaria control. Bull World Health Organ 1990, 68 :761–8.        primarily focused to control malaria in Africa. We have
                                                                      elucidated the multifarious reasons in explicit manner
6.   Curtis CF. Control of malaria vectors in Africa and Asia. In :
     Radcliffe RB, Hutchison, WD editors. Radcliffe’s IPM world
                                                                      which prompted this bold pragmatic decision. The
     textbook, St. Paul, MN: University of Minnesota; 1996.           failure of RBM was essentially due to development of
     Available from: http://ipmworld.umn.edu, accessed on October     resistance by malaria vectors in Africa to synthetic
     22, 2007.                                                        pyrethroids. In that scenario reintroduction of DDT was
7.   DDT ban takes effect. Available from: http://www.epa.gov/        indeed a great success in countries in South African
     history/topics/ddt/01.htm, accessed on October 23, 2007.         region. Similar success stories happened in South
8.   DDT-the age of old mosquito control. P- Posted by Dr D.          American countries also. This turn of events, however,
     Raghunatha Rao on September 18, 2006. Available from:            was not appreciated by donor agencies from European
     http://www.medicalnewstoday.com/your opinions php?               Union and United States till WHO lifted the ban. DDT
     opinionid =11543, accessed on October 22, 2007.                  deployment was not promoted due to its low cost as
9.   Bioenvironmental Strategy for Malaria Control. Studies on        presumed by the author1. DDT is currently costlier in
     the reliance of DDT, HCH and malathion in Vector Control         the global market compared to synthetic pyrethorids.
     Programme. Available from: http://www.mrcindia.org/              The author further questions the wisdom of deployment
     MRC_Profile/alternate_strategy/insecticide_VCP.pdf,              of DDT in North Eastern States in India and he claims
     accessed on October 22, 2007.                                    malaria incidence is increasing in those States. This
10. The World Bank and DDT use in India. Available from: http:/       erroneous statement reflects his ignorance of the fact
    /lnweb18.worldbank.org/ESSD/envext.nsf/50ByDocName,               that malaria vectors in this region are still susceptible
    accessed on October 24, 2007.                                     to DDT and the recent malaria outbreak in Assam was
11. To control malaria, We need DDT. 21st Century Science and         effectively controlled by its use. It is also incorrect to
    Technology.        Available     from:       http://www.          say that malaria is resurging in India. The author is
    21stcenturysciencetech.com/articles/fall02/DDT.html,
                                                                      probably ignorant of the epidemiological reports of
    accessed on October 23, 2007.
                                                                      National Vector Borne Disease Control Programme
12. Mosquito Control and Environment. Available from: http://         which clearly indicate that malaria incidence in India
    www.the conscientioushome.net/articles.php?con_id =169,
                                                                      has been stable for last many years and deaths due to
    accessed on October 23, 2007.
                                                                      malaria is declining. This has been internationally
13. DDT. Available from: http://www.pan-UK.org/pestnews/              recognized as in a recent publication citing India as a
    actives/ddt.htm, accessed on October 27, 2007.
                                                                      winner along with Brazil, Eritrea and Vietnam in
14. Frequently asked questions on DDT use for disease vector          effectively controlling malaria when globally other
    control. Available from: http://www.who.int/malaria/docs/         malarious countries have failed3.
    FAQonDDT.pdf, accessed on October 23, 2007.
15. DDT’s resurrection. Available from: http://pubs.acs.org/              The author’s contention that continued use of DDT
    subscribe/journals/esthag-w/2007/aug/science/nl_ddt.html,         would harm the human race has not been substantiated
    accessed on October 27, 2007.                                     by the scientific data available so far. WHO decided to
586                                     INDIAN J MED RES, DECEMBER 2007

lift the ban on DDT in September 2006 after a thorough     ban of DDT in agriculture. Use of DDT in malaria
and careful consideration of whole gamut of scientific     control strictly adhering to WHO protocols and
data generated till that date on health hazards and        guidelines hopefully will mitigate people from the
environment impact of DDT. This decision has been          scourge of malaria in Africa and other malarious
welcomed by many international agencies, WWF and           countries.
environmentalists who support malaria control in Africa
and in other countries. In our editorial we tried to             A.P. Dash†, K. Raghavendra & M.K.K. Pillai*
elucidate scientific facts supporting this pragmatic               National Institute of Malaria Research (ICMR)
decision of WHO. The author seems to have no                                  22, Sham Nath Marg, Delhi 110054
comprehension of enormous quantities of DDT that was              *37, Saakshara Apartments, A-3, Paschim Vihar
indiscriminately used both in developed and developing                                   New Delhi 110063, India
countries from the period of World War II since early                                        †
                                                                                               For correspondence:
1940s till 1972 when US banned DDT. However, this
                                                                                         apdash2@rediffmail.com
large scale use of DDT did not cause any catastrophic
effects or any epidemiological mass effect on human
race as evidenced and should clearly dispel the                                      References
unwarranted alarming fear. Since DDT is restricted         1.   Siragnaname N. Resurrection of DDT: need for caution. Indian
mainly for malaria vector control the envisaged impact          J Med Res 2007; 126: 584-5.
on human health and environment would be further           2.   Dash AP, Raghavendra K, Pillai MKK Resurrection of DDT -
reduced. The sermonizing statement that DDT should              A critical appraisal. Indian J Med Res 2007; 126 : 1-3.
not be used in agriculture is redundant as DDT ban in      3.   Barat, L M. Four malaria success stories: How malaria burden
agriculture is implemented in most countries including          was successfully reduced in Brazil, Eritrea, India, and Vietnam.
in India. Our editorial has not mentioned anything about        Am J Med Hyg 2006; 74 : 12-6.