SOURCE: Bulletin of Environmental Contamination Toxicology, 57:705-712, 1996
In trying to calm the fears of Tampa residents, representatives for the Florida
Department of Agriculture have made public statements that after application,
malathion "breaks-down" in a matter of hours. What they don't tell
you is that malathion can actually break-down into compounds which are more
poisonous than the malathion itself. This is, in fact, the conclusion of research
from a graduate project by researcher N. E. Barlas at the Department of Biology,
Hacetepe University, Turkey. Barlas went on to say, "The disappearance
of pesticide residues at a given location does not mean the end of the problem.
Pesticides can be translocated, bioconcentrated or converted into more dangerous
chemicals." The breakdown fate of malathion was studied by adding malathion
to soil samples containing 6 species of soil bacteria known to breakdown the
pesticide. After 10 days the samples were analyzed. Malathion content had reduced
from 100 down to 25 micrograms, so therefore, the Florida Department of Agriculture
spokes people are correct when they say it "breaks down" relatively
quickly (although in this case not in a matter of hours). However, even more
important, Barlas found that new chemicals were formed in this breakdown process
including 14 micrograms of monocarboxylic acid and about 8 micrograms of the
highly toxic malaoxon. Barlas then exposed mice to the technical grade malathion
and another group to the breakdown products just mentioned. Results showed even
the mice exposed to the break-down products of malathion showed significant
decreases in spleen weights and significant changes in liver blood tests which
were suggestive of liver damage. Barlas summarized by stating, "It may
be concluded that commercial malathion and it's degradation products together
have detrimental effects on mice over a period of 15 weeks of treatment."
Department of Biology, Faculty of Science, Hacettepe University, Turkey