Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Pesticide pains brain


Mississippi’s illegal roach killer excites attention.

The brain centre targeted by traces of a widely used pesticide has been identified by US researchers. The finding could help explain symptoms seen in people exposed to the pesticide in their homes.

Several years ago, some US homes were sprayed illegally with the crop pesticide methyl parathion, known to be toxic at high doses. Evidence has since emerged linking the exposure to anxiety, sleeplessness and depression in people living in the houses.

Low levels of the ’cotton poison’ may affect a brain centre involved in sleep-wake cycles, memory and anxiety, Hong Zhu revealed at the Experimental Biology 2002 meeting in New Orleans on Monday.

The findings may help to nail methyl parathion as the cause of the symptoms: "It’s putting a name to a problem," says group leader Robert Rockhold. Little is known about the long-term health effects of these and other organophosphates.

Mississipi dealt a killer

Using methyl parathion indoors is illegal in the United States. The chemical is one of the most toxic and widely used in a group of organophophate pesticides, all of which affect the nervous system. It is banned from use on fruit and vegetables in some countries but is sprayed on field crops such as wheat, cotton and rice worldwide.

However, in the cotton-growing US states, rackets sprang up using agricultural methyl parathion stocks as a cockroach killer. In one notorious Mississipi incident, illegal pest-control operators sprayed more than 1,500 homes and businesses between 1994 and 1996. Those exposed reported acute nausea and vomiting plus longer-lasting behavioural problems.

In 1997, the Environmental Protection Agency and pesticide manufacturers tightened their regulations on the production of methyl parathion and educated the public about its toxicity. But there are concerns that such scams may still go on: "It’s still possible to divert the pesticide," says Rockhold.

Janice Chambers, who studies the toxicity of organophosphates at Mississipi State University, doubts that indoor use is still a problem "People are very alert to it now," she says. At the time, affected buildings were cleaned up and the perpetrators prosecuted.

Organophosphates break down quickly in the body, explains Chambers. Children who run into sprayed fields are a greater cause of concern because they lack the enzyme that naturally detoxifies such chemicals. Agricultural workers involved in crop spraying are also at greater risk.

Locus action

A high dose of methyl parathion can cause respiratory failure and death. The chemical overstimulates the nervous system by interfering with the enzyme acetylcholinesterase, which breaks down the nerve-excitation chemical acetylcholine.

Using rats, Zhu and her colleagues placed an electrode in a small area of the brainstem called the locus coeruleus. This contains high levels of acetylcholinesterase and has been implicated as a site of action of other organophosphates.

Sure enough, a small injection of methyl parathion triggered the nerve cells there to fire. "The neurons go crazy," says Zhu.

This over-excitation may explain the behavioural changes seen in exposed people, Zhu suggests. She plans to explore the effects of "24/7" exposure that those working in contaminated homes or buildings might experience.

Getting to grips with the biological action of such toxic substances is important, agrees Chambers. "We can then better understand if things are likely to cause a big problem and eliminate them," she says.

But ditching organophosphates without good grounds is premature, she maintains. They risk being replaced by other chemicals about which even less is known. "We need to be rational," she says.

HELEN PEARSON | © Nature News Service

More articles from Health and Medicine:

nachricht NIH scientists describe potential antibody treatment for multidrug-resistant K. pneumoniae
14.03.2018 | NIH/National Institute of Allergy and Infectious Diseases

nachricht Researchers identify key step in viral replication
13.03.2018 | University of Pittsburgh Schools of the Health Sciences

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>