Acute Changes in Human EEG After Exposure to Low Doses of Oxydemeton Methyl

Axel Muttray*, Frank Padberg*, Detlev Jung*, Hans R. Rohlfing**, Monika Schulz**, Johannes Konietzko*

*Institute of Occupational, Social, and Environmental Medicine, University of Mainz, Germany
**SLVA Oppenheim, Experimental Station for Horticulture, Oppenheim, Germany

(1)Corresponding author: Dr. A. M. Muttray
Institut für Arbeits-, Sozial- und Umweltmedizin der Johannes Gutenberg-Universität
Obere Zahlbacher Straße 67, 55131 Mainz, Germany
Telephone: 06131/173121, Fax: 06131/176680

Abbreviations:
    EEG: electroencephalogram
    qEEG: quantitative electroencephalogram

CEJOEM 1996; 2(4):367-374


Abstract: Biological monitoring of farmers exposed to organophosphorus pesticides mainly consists of determination of cholinesterase activity. Animal experiments indicate that quantitative EEG (qEEG) analysis may be more sensitive, but there are no data concerning human beings. In a pilot study we recorded the EEG of farmers spraying oxydemeton methyl. The exposure of 30 minutes was low and the cholinesterase remained unchanged. In the closed eye condition spectral power of the ß2-band of the higher exposed subgroup (n=4) was significantly elevated in comparison to the lower exposed subgroup (n=7). This finding corresponds to the changes in qEEG that were reported from workers and monkeys exposed to sarin. Regarding the low exposure of the farmers, it is improbable that the changes in EEG are only due to inhibition of cholinesterase in the brain. Also, interactions with presynaptic muscarinic receptors should be considered.

Key words: Exposure, pesticides, oxydemeton methyl, cholinesterase, EEG


Acknowledgements
This study was partly supported by grant of the Zentrum für Umweltforschung, University of Mainz (Kapitel 1512 Titel 54701/81201). The authors are very grateful to Dr. Lewalter, Bayer AG, for the determination of oxydemeton methyl, and to Mr. Becker, Institut für Technik der Fachhochschule Geisenheim, for his helpful work regarding the measurement of exposure. EEG data are part of the medical dissertation of F. Padberg, in preparation. 
Received: 5 August 1996
Accepted: 14 November 1996
Posted: 31 May 2000
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