DDT Alternatives in Mexico

Public health experts in Mexico, along with the nation's Malaria Control Program (MCP), are searching for new ways to fight malaria without using DDT. A multi-disciplinary team funded by the International Development Research Center (IDRC) is looking at ways to manage the local environment to reduce the incidence and spread of malaria. The team is focusing on the State of Oaxaca which is the main site of malaria outbreaks in Mexico. "We're looking at malaria from many different angles including the molecular biology of the vector and the parasite, community perceptions of malaria, statistical analyses, and a geographic information system (GIS)-based surveillance system,” says Juan Hernandez, Director of Informatics at the National Institute of Public Health. The MCP's long-term goal is to prevent future outbreaks of malaria, without harming the local environment. DDT has been the main tool used in fighting malaria but since it is dangerous to the environment, the MCP has decided against using it. The research team used geographic information system (GIS) tools to analyze different areas in Oaxaca in terms of malaria incidence and frequency, elevation, climate, hydrology, distance to rivers and roads, and short-range human movements. The team found that cases of malaria occurred more frequently in areas with closely clustered villages and in places where health facilities are scarce. The researchers are now focusing on humans as the main vector. A vector is an organism that carries a disease-causing microorganism from one host to another. The researchers have found that mosquitoes merely introduce the disease into the population but without the availability of medical treatment the people with the disease cause it to spread. The MCP is also working on an algae removal strategy, the purpose of which is to reduce the number of disease carrying mosquitoes in the area; they are giving people who have had malaria before malaria medicine to prevent them from relapsing; and they are working on rapid diagnosis of people showing symptoms of malaria to get them treatment more quickly. The rapid diagnosis approach is currently being evaluated in 20 different areas. The new malaria control strategies are working well, between 1998 and 2001 the number of malaria cases had fallen sharply.

Just for Fun: A DDT Limerick

A mosquito was heard to complain

A mosquito was heard to complain
That a chemist had poisoned his brain
The cause of his sorrow
Was paradichloro
Diphenyltrichloroethane.

 by Dr. D. D. Perrin

DDT Linked to Early Miscarriages

A recent study conducted at the Harvard School of Public Health has shown that women with high levels of DDT in their bloodstream are far more likely to miscarry in the early weeks of pregnancy than those with lower levels. The participants in the study were newly married, healthy, nonsmoking textile workers in China, who were trying to get pregnant. The women ranged from ages 20 to 34. Even though DDT was banned decades ago, the chemical residue can be found in most people, no matter how far they lived from where DDT was used or produced. The Chinese women who participated in this study were found to have an average level of DDT residues about ten times higher than those ordinarily found in the United States. The levels were similar to those found in countries where DDT was more recently used. The study found that the women who had the most DDT in their system were more likely to miscarry in the early weeks of pregnancy, before they even knew they were pregnant. The researchers found that for every additional 10 nanograms of DDT per gram of serum, a woman’s chance of early miscarriage rose by about 17 percent. The chance that DDT is linked to infertility was not investigated by this study.

For more information: http://www.sciencedaily.com/releases/2005/09/050912124225.htm
For the full version of the study: http://aje.oxfordjournals.org/cgi/reprint/kwi275?ijkey=h9AKIxsz45iaLkB&keytype=ref

The Beginnings of DDT

In 1948, Dr. Paul Muller received the Nobel Prize for Medicine for his discovery of DDT’s toxic effect on insects. Tiny amounts of this chemical could kill a large amount of insects and studies showed that it was not very toxic for plants or animals. It was first put to use in 1939 to wipe out the Colorado potato beetle that was destroying Switzerland’s potato crop. It was then used successfully to protect soldiers from mosquitoes, body lice, and other disease spreading insects. DDT had proven to be exactly what Muller had been looking for.

Dr. Muller had been working in the dye division of the J. R. Geigy Corporation researching natural products to be used as pigments and tanning agents for leather. He was researching this until 1935 when he was assigned to develop an insecticide. He was looking for a compound that would have a rapid potent toxicity for the most species of insect; that would be stable enough to last long periods of time; and that would cause little or no damage to plants and animals. DDT satisfied all of Muller’s requirements and it was thought to be an ideal insecticide, until people realized it was being overused and because of the chemical’s persistence, there was too much of it in the environment. This created a hazard to animal life and spurred people like Rachel Carson to fight and have DDT banned.