The International Mussel Watch 



of human milk were higher in lesser developed countries like China, India and Mexico; whereas in 

 countries that have prohibited or severely restricted the use of DDT, the levels were almost an order 

 of magnitude lower. 



The scientific team that conducted the study concluded that the high levels of DDT were due 

 to continuing and extensive use of DDT as an insecticide in agriculture and in disease vector 

 control. In these countries, the elevated levels of DDT-DDE in mothers milk indicate that the intake 

 of the DDT family, by some or most breast-fed infants in the participating countries, exceed the 

 acceptable daily intake (ADI) of 5|!g/kg body weight established by the United Nations Food and 

 Agriculture Organization and the World Health Organization. In the developing countries, the ADI 

 is exceeded several fold by most infants. The same investigation showed that the levels of the 

 industrial chemical polychlorinated biphenyls (PCB's) were higher in Japan and European 

 countries and were almost undetectable in China, India and Mexico. 



However, there is documented increased usage of electrical components which have PCB's 

 as potting fluids in transformers and condensers. Recent reports of spills of these PCB's on the 

 African continent and their potential movements in the coastal zone, exemplify the concerns of 

 environmental scientists. These industrial chemicals have been linked to the declining mammal 

 populations in the Baltic and North Seas and in California coastal waters. Are the concentrations 

 of PCB's in any zones of the tropics and southern hemisphere attaining levels that might jeopardize 

 marine organisms? 



These data support the crucial need for global scale environmental monitoring of these 

 persistent agriculturally- and industrially-based chlorinated hydrocarbons. The lack of scientific 

 resources, instruments, laboratories and available scientists coupled with the high level of usage of 

 chlorinated compounds in many regions, argues for a carefully conducted assessment to measure 

 these compounds on a global basis. This problem underlines the need for reliable information on 

 the distribution of these toxic chemicals in the biosphere such that appropriate regulatory policies 

 can be considered at the national and international level. 



Modern societies have benefited substantially from the production and use of synthetic 

 chemicals as well as the increased mobilization of naturally occurring chemicals (e.g. mining and 

 petroleum production). It has been estimated that at least 1000 of these chemicals, a small 

 percentage of the hundreds of thousands produced, are of environmental concern (Butler, 1976; 

 Sheehan et al., 1984). The chlorinated hydrocarbons are among these. 



Lessons learned from the problems with DDT and related persistent chlorinated pesticides 

 resulted in development and use of other pesticides such as the thiophosphate and carbamate 

 families of pesticides. These newer pesticides generally, but not in all cases, have less persistence 



