Ma. Mora, TRANSBOUNDARY POLLUTION - PERSISTENT ORGANOCHLORINE PESTICIDES IN MIGRANT BIRDS OF THE SOUTHWESTERN UNITED-STATES AND MEXICO, Environmental toxicology and chemistry, 16(1), 1997, pp. 3-11
The hypothesis that migratory birds accumulate persistent organochlori
ne pesticides (POPs) during the winter in Latin America has been preva
lent for many years, particularly since 1,1,1-trichloro-2,2-bis(p-chlo
rophenyl)ethane (DDT) was banned in the United States in 1972. It has
been suggested that peregrine falcons (Falco peregrinus), black-crowne
d night herons (Nycticorax nycticorax), white-faced ibises (Plegadis c
hihi), various migratory waterfowl and shorebirds, and other avian spe
cies accumulate higher concentrations of POPs while on migration or on
their wintering grounds in Latin America. Nonetheless, the data obtai
ned thus far are limited, and there is no clear pattern to suggest tha
t such accumulation occurs on a widespread basis. In this review wildl
ife contaminant studies conducted along the U.S.-Mexico border and thr
oughout Mexico are discussed. The results for the most part seem to in
dicate that no major accumulation of 2,2-bis(p-chlorophenyl)-1,1-dichl
oroethylene) (DDE), the most persistent organochlorine compound, has o
ccurred or been reported for most parts of Mexico. The majority of the
DDE values in birds from Mexico were similar to those reported in bir
ds from the southwestern United States during the same years. More wor
k needs to be done, particularly in those cotton-producing areas of Me
xico where DDT was applied heavily in the past (e.g., Chiapas and Mich
oacan). Because DDT is still used for malaria control and may still be
used in agriculture in Chiapas, this state is probably the one where
most migrant species would still be at a significant risk of increased
accumulation of DDE and DDT.