February 2nd, 2017
In a paper published in Genome Biology on 24 January, researchers from Tamil Nadu’s Madurai Kamaraj University produced evidence that a popularly used insecticide caused diabetes and weakened glucose tolerance in those directly exposed to the insecticide.
What are organophosphates?
An organophosphate (OP) is the general name for esters of phosphoric acid (esters are organic compounds made by replacing the hydrogen of an acid by another organic group).
Many of the most important biochemicals are OPs, including DNA and RNA.
What are organophosphate pesticides and why are they prominent?
OPs are also used as insecticides. They were developed in Germany in the 1940s and came to be widely used due to their effectiveness and minimal environmental impact.
OP pesticides degrade rapidly when exposed to sunlight and soil. This ability to biologically degrade swiftly made them attractive insecticides.
These insecticides act on the nervous system of insects and animals, essentially poisoning them and thus combating pests.
The effectiveness and minimal environmental impact of OP insecticides came at a costly price: they adversely affect the health of any human exposed to them. They can be absorbed through the lungs or skin or by eating them on food.
OP pesticides are of concern to scientists because their effect on insects’ nerve function can also occur in humans exposed to the insecticide. When exposed in considerable quantities, these insecticides irreversibly block certain enzymes which are critical to nerve function.
In small quantities too, OP insecticides can be hazardous. They can hamper the brain development in fetuses and young children.
OPs are also components of chemical weapons like sarin gas which attack the nervous system of those exposed.
Action against OP insecticides
The Environment Protection Agency (EPA) of the United States banned most uses of OPs in 2001. Repeated research has highlighted the adverse effects of these insecticides on human health and scientists have been calling for their strict regulation or complete ban for years.
However, they are still used in agriculture and pest control in public spaces around the world. This is largely due to their biodegradable nature.
The research by the Madurai Kamaraj University team
The diabetogenic (diabetes-inducing) nature of OPs was recently reported, but the underlying molecular mechanism has been unclear. The Madurai researchers aimed to understand this so that the process could be clarified.
To understand the molecular mechanism, the researchers focussed on finding how the pesticide worked and degenerated. They found that the ability of the pesticide to produce glucose from non-carbohydrate sources such as fat and proteins was most prominent.
“The pesticide is degraded into short-chain fatty acid, particularly acetic acid. It is well known than acetic acid causes glucose, elevated blood sugar levels and glucose intolerance,” Dr Velmurugan says.
The researchers studied the effects on mice. They ascertained the role of acetic acid in elevating blood sugar level in mice by administering sodium acetate orally and through rectal route; the rectal route led to more blood sugar increase than the oral route.
A survey of about 3,000 people in villages found that the prevalence of diabetes in people directly exposed to the OP insecticides was three times higher than in people who were not directly exposed to the same.
“The study clearly shows the prevalence of diabetic conditions mediated by microbial degradation of the pesticide in humans,” Subbiah Ramasamy, the corresponding author of the paper, told The Hindu. “So the usage of this pesticide should be seriously reconsidered.”
Organophosphates in India
OPs have been extensively studied in India, and scientists have continuously highlighted their adverse effects and called for their ban.
The World Health Organization (WHO) has been trying for years to get India to ban the pesticides. A famous example is the July 2013 incident of OP poisoning which killed 23 school children. The children died after eating lunch prepared with contaminated oil.
The Logical Indian take
The Logical Indian congratulates the Madurai Kamaraj University team for their research and valuable findings. The scientific evidence for the toxic effects of OP insecticides is overwhelming. The WHO and scientists from all around the world have been calling for the ban of these insecticides for years. India needs to take strict action against OP insecticides and eliminate their usage to safeguard human life.