An urgent need to reclassify pesticides of massive use in Argentina

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The current classification ignores the scientific evidence which demonstrates how dangerous they are.

July 2011, Argentina

According to declarations from the sector Chambers, Argentina consumed 340 million litres of pesticides and herbicides in the last year; and this quantity is increasing 15% to 20% each year. These poisons are sprayed, fumigated and applied to areas inhabited by 12 million people. For a long time, the residents of the affected localities have been denouncing to suffer from serious diseases as a consequence of their being contaminated by the pesticides. This situation was confirmed at the 1st and 2nd Meeting of Physicians of the Fumigated Towns, at the Córdoba Medical Sciences Faculty [1] and Medical Sciences Faculty of the Rosario National University [2], in 2010 and 2011, respectively.

There is substantial public demand to reclassify pesticides in Argentina. This demand is sound: depending on how pesticides are classified, the provincial and municipal regulations determine the distances between fumigated (sprayed) and inhabited areas.

Currently, the classification is made according to the quantity in milligrams of poison that, when fed to rats, kills 50% of the population tested (Lethal Dose test or LD50); the less the quantity of poisonous substance is required, the higher the level of toxicity is attributed to that substance. As such, this form of measurement ignores medium and long term effects, including oncogenic, reproductive, immunological and endocrine ones.

humans are not rats of 70 kgs

In the light of these facts, Glyphosate should be re-classified as level Ib (highly hazardous; the WHO recommended classification of pesticides by hazard), particularly because of the scientific and epidemiological data, showing that its accumulation in the body is connected to congenital malformations and spontaneous abortions [1, 3].

Furthermore, the current toxicological classification of acute effects of pesticides doesn’t take into account a new set of information and scientific data, which show the acute damage of these poisons for agricultural use on humans, and that are different from the findings in rodents, highlighting patterns specific to humans. These new data stem from a number of studies which have detected the effects of various pesticides in people who had ingested them in attempted suicides; there is no other way to research the effects of these toxic substances on our species, because it would be unethical to test them on humans.

One third of suicides worldwide are caused by ingestion of pesticides. In Asia this figure rises to 50% of all suicide attempts. Dawson et al. [4] published (Oct 2010) a research study of the evolution of around 8.000 people who entered two hospitals in Sri Lanka due to pesticides ingestion. In their work, they could, irrefutably, determine the precise levels of acute human toxicity relative to the different pesticides. In this cohort group, 10% of the patients died, but a great variation in the percentage case fatality for each pesticide was observed.

Pesticides of the same chemical class and/or of the same toxicological class, sometimes presented very different clinical effects. For instance, dimethoate and malathion (both class II organophosphates) showed a Percent Case Fatality of 20,6% and 1,9%, respectively (Dawson et al., 2010). This study is unique for two reasons: because of the large number of cases analysed and because it is a prospective study, which involved the follow-up of specific groups of patients (prospective cohort). The authors Dawson et al. (2010) recognize that : “Unfortunately, at present, regulatory decisions are based on a classification of pesticide toxicity that is largely based upon rat oral LD50s. The scientific basis for extrapolating this classification to human poisoning with class II pesticides is weak.”.

The same authors also point out that: “Rodents handle xenobiotics differently to humans; as an example, they have greater capacity for metabolic detoxification of organophosphates. And unlike human patients receiving intensive care, they do not receive any treatment in the toxicity studies. It is therefore not clear that a pesticide with low toxicity in rodents should be safe in humans and vice versa.”

Paraquat, dimethoate and fenthion were responsible for 17,6% of the total hospital admissions, but 47% of the total deaths. Paraquat was the most lethal, with 42.7% of all fatalities. Chlorpyriphos was the most common, with 1376 suicide attempts, but a case fatality of 7.6%. Endosulphan is less utilized (it is forbidden in Sri Lanka) with a case fatality of 22.2%. Dimethoate was very used and originated 172 deaths: 20.6%. Glyphosate originated 21 fatalities with a case fatality of 2.4%. The Abamectin, classified as Class IV by the WHO, had a case fatality of 11.1%. A global figure for fungicides showed a fatality rate of 6.1 deaths for 100 cases of self-ingestion.

These results provide a range in the toxicity of pesticides that would allow for a more reliable classification of the agricultural pesticides based on their toxicity in humans, which would be more reliable as based on human physiology, and that will depart markedly from the WHO classification of toxicity that is based on the physiology of the rat.

In the current classification, Paraquat (estimate case fatality of 47%), Endosulfan (22%) and Dimethoate (20.6%) are reported as class II by the WHO (moderately hazardous) while they should be stated as class Ia (extremely hazardous) and restricted all over the world, showing the inadequacy of the current classification based on data derived from tests on rats.

The data presented by Dawson et al., add on to the retrospective studies of suicides in Taiwan [5], India [6] and Sri Lanka [7], which together represented an analysis of more than 15.000 people and reached similar conclusions: the need to adapt the toxicological classification of pesticides according to their effects on humans.

This is also what other experts in Public Health across the world are calling for, including researchers from the U.S. Harvard Public Health School [8] asking for “An urgent need to restrict access to pesticides based on human lethality” and “An urgent need to modify the WHO classifications”.

This problem, as we see, is not exclusively Argentinian; but in this country there is a very high level of urgency and need, considering the quantity of pesticides that are being sprayed over the population and the accelerated growth in the use of pesticide in rural areas. For all of the reasons detailed here, the University Network for Health and Environment/Network of the Physicians of Fumigated Towns demand that pesticides be urgently reclassified in Argentina, according to the acute and lethal effects already proven in humans and the data on medium and long term damages (oncogenic, reproductive, immunological and endocrine).

Nowadays, there is no justification whatsoever to continue to follow the old classification of pesticides and to authorize the spraying, aerosolization and fumigation of substances that have been demonstrated to be poisonous for people. We recognize, however, that there are enormous economic interests in maintaining the use of these poisons without restrictions, to, supposedly, sustain agricultural production, but this accounts for a violation of the right to health of the population.

1- Avila Vazquez M, Nota C. Informe 1º Encuentro Médicos de Pueblos Fumigados. UNC. Ag 2010

2- Declaration of 2nd MEETING OF PHYSICIANS OF SPRAYED AND FUMIGATED TOWNS AND VILLAGES. UNR. Ab 2011 Red Universitaria de Ambiente y Salud / Médicos de Pueblos Fumigados 

3- Antoniou M, Mostafa Habib M, Howard C, Jennings R, Leifert C, Onofre Nodari R , Robinson C, Fagan J. Roundup and birth defects: Is the public being kept in the dark? Earth Open Source, 2011

4- Dawson AH, Eddleston M, Senarathna L, Mohamed F, Gawarammana I, Bowe SJ, Manuweera G, Buckley NA. Acute human lethal toxicity of agricultural pesticides: a prospective cohort study. PLoS Med. 2010 Oct 26;7(10):e1000357. South Asian Clinical Toxicology Research Collaboration, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka.

5- Lin TJ, Walter FG, Hung DZ, Tsai JL, Hu SC, Chang JS, Deng JF, Chase JS, Denninghoff K, Chan HM. Epidemiology of organophosphate pesticide poisoning in Taiwan Clin Toxicol (Phila). 2008 Nov;46(9):794-801. Department of Emergency, Kaohsiung Medical University Hospital, Taipei, Taiwan.
6- Srinivas Rao Ch, Venkateswarlu V, Surender T, Eddleston M, Buckley NA. Pesticide poisoning in south India: opportunities for prevention and improved medical management. Trop Med Int Health. 2005 Jun;10(6):581-8. University College of Pharmaceutical Sciences, Kakatiya University, Warangal, India. 

7- Eddleston M, Eyer P, Worek F, Mohamed F, Senarathna L, von Meyer L, Juszczak E, Hittarage A, Azhar S, Dissanayake W, Sheriff MH, Szinicz L, Dawson AH, Buckley NA. Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study. Lancet. 2005 Oct 22-28;366(9495):1452-9. South Asian Clinical Toxicology Research Collaboration, Centre for Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, UK.

8- Miller M, Bhalla K. An urgent need to restrict access to pesticides based on human lethality PLoS Med. 2010 Oct 26;7(10):e1000358. Department of Health Policy and Management, Harvard School of Public Health, Boston, Massachusetts, United States of America.

Dr.Medardo Avila Vazquez

Medico Pediatra y Neonatólogo

Coordinador Red Universitaria de Ambiente y Salud

Médicos de Pueblos Fumigados


Translated by Equivita. Rome, Italy

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7 respuestas a An urgent need to reclassify pesticides of massive use in Argentina

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