Emergence of new poisons: A case of pendimethalin poisoning from rural India

To the Editor:

The WHO recogniszes pesticide poisoning to be the single most important means of suicide globally. Pesticide self-poisoning is a major public health and clinical problem in rural Asia, where it has led to a very high-case fatality ratios than in the developed world. Suicide is an important cause of premature mortality accounting for an estimated 849,000 deaths every year.¹

In many agricultural communities of low- and middle-income countries pesticide self-poisoning accounts for many of these deaths.² Based on the finding that pesticide ingestion accounted for over 60% of suicides in many rural areas of China and South-East Asia, Gunnell and Eddleston² estimated that there may be as many as 300,000 deaths each year from intentional pesticide poisoning in these regions alone. This makes it likely that pesticide poisoning is the most frequently used method of suicide worldwide.

This is mostly caused by the Organophosphates (most common in India), Organochlorines and Aluminium Phosphide compounds; which are an integral part of agriculture & are readily available at a cheap rate. Their poisoning is typically suicidal, at times accidental and rarely homicidal in nature.³ In developing countries, the mortality is much greater with high-case fatality up to 46% (generally more than 15%).⁴ Due to the extremely high intrinsic toxicity of the existing compounds, new chemicals of high potency and low toxicity continue to be developed for example, Imidacloprid, Pendimethalin, Pencycuron⁵ etc. They are classified as a &moderate toxic&, and generally demonstrate low human lethality but at times they may be hazardous.⁵

Pendimethalin (C13H19N3O4) is a dinitroanaline herbicide; freely available, widely used and supposed to be a slightly toxic compound in EPA toxicity class III. Only a few cases of its toxicity have been reported till date around the world, but not in India.

Case report

A 25-year-old male farmer was admitted in casuality at 7.30 pm with an acute episodes of intractable vomiting and altered sensorium. He was completely alright at 4.00 PM when he deliberately consumed approx. 50 ml of herbicide Pendimethalin 30% E.C. to end his life. After 10&15 min, he started having recurrent episodes of watery vomiting, headache, burning sensation and pain in throat and abdomen. Later on he became drowsy followed by altered sensorium and unconciousness.

At hospitalization, he was restless, confused, and delirious. Relatives denied consumption of any drug, poison or medications. Vital signs were revealed such as temperature 98 F, pulse rate 74/minute, B.P.:122/80 mmHg and respiratory rate: 21/minute with bilateral vesicular breathing. Neurological examination revealed GCS of 9/15 (E2V3M 4) with reduced movements of all four limbs and normal, reacting pupils. The examination of other systems as well as laboratory investigations including complete blood count, GBP, erythrocyte sedimentation rate, routine chemistries, liver and renal function test were within the normal limits.

In this case the diagnosis of Pendimethalin poisoning was made by reliable information from the victim, his relatives, used containers of the poison brought by them, clinical findings and police investigations. He was treated symptomatically with IV fluid, Omeprazole, and Antacids along with broad spectrum antibiotics and showed good response. On the next day, he regained consciousness without any sensory motor deficit. He was irritable and still having burning sensation in throat and pain in epigastrium. On the third day, his psychiatric reference was done for his irritable behavior and found to be suffering from impulsive personality with depressive symptoms due to excessive financial burden as he was running out of heavy debts. He was advised tablets such as Escitalopram 10 mg HS and Zolpidem 10 mg SOS.

After prolonged interrogation and talking to the patient and his relatives, this unfortunate incidence was found to be purely suicidal in nature. All the legal protocols were done as per the institutional rules. In follow-up visit after 1 week, he was completely alright.

There is dearth of literature on Pendimethalin toxicity, it is considered practically non-toxic to humans. In large ingestions, its toxicity is principally manifested by head ache, nausea, vomiting, sore throat, retching and haematemesis etc.

Its toxicity is invariably associated with oral ingestion. In a study of 71 cases, 69 were associated with its ingestion; intentionally or accidentally. Among them, 20 remained asymptomatic, 38 had mild effects (nausea, vomiting and sore throat) and only seven patients develop significant toxicity in the form of severe retching, vomiting of blood etc. Four patients died as a result of also taking other herbicides and because of inadequate airway management.⁶

In another case report, a 73-year-old man developed nausea, epigastric pain and corrosive gastroduodenal injury after accidental ingestion of pendimethalin.⁷ Our patient also presented with significant neurological manifestations like delirium and unconsciousness which has not been reported earlier. This case is being reported on account of its rarity and significance for community health. To the best of our knowledge, not a single such case has been reported so far in India.

After accidents and maternal mortality; suicide by ingestion of pesticides agrochemical compounds is the leading cause of death among the young in India. It is ranked as third leading cause of death in the age group of 15&44 years.⁸ Of the 1,87000 people who committed suicide in India in 2010, around half (49% men and 44% women) consumed poison, mainly pesticides.⁸ Over last few decades poison control training and research centers have been created globally to encounter this problem. But unfortunately there is a complete lack of such centers in rural areas where these are needed most.

Complete ban on the highly toxic agrochemical compounds is not feasible therefore their substitution by the newer less toxic compounds in highly affected areas may be of great value. But such incidences are a big challenge especially in rural areas where health care facilities are sorely lacking. Their exposure should not be ignored, as their clinical consequences are not very well described and outcomes rely on early recognition, prompt referral and timely management. The treating physicians should be vigilant and must have a close watch till full recovery. In addition, the importance of preventive measures and public awareness also cannot be ignored in saving precious lives and should be implemented at different levels. Keeping in view these facts; this case is being presented to add in the existing volume of knowledge regarding pendimethalin toxicity.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.