Cholinesterase activities determination in frozen blood samples: an improvement to the occupational monitoring in developing countries

1 Studies were carried out on rural workers in Brazil to determine the decr ease in the activity of plasma butyrylcholinesterase (BChE), erythrocyte ch olinesterase (AChE) associated with exposure to organophosphorus pesticides (OP). The goal of this work is to help prevent injury to these workers. 2 In developing countries the distance between area of pesticide use and re ference laboratories is a drawback for analytical techniques, since choline sterase activity determinations require fresh blood samples. Field methodol ogies can be a useful alternative to laboratory tests, however they are not as sensitive as those found in laboratories. 3 The modification of Ellman's Method presented in this paper allows blood samples to be frozen and maintain enzymatic stability: 7 days for AChE and 3 days for BChE. The proposed method is also more sensitive than Ellman's M ethod Modified by Magnotti (EMMM). 4 The results suggest that the Ellman Method Modified by Oliveira-Silva (EM MOS) is valid for monitoring procedures. This method represents an importan t contribution to the process of monitoring OP exposures, since the evaluat ions no longer have to be conducted near the site of OP use.