Introduction High levels of cotinine have been related to the occurrence of green tobacco sickness (GTS), however chronic exposure to nicotine develops tolerance. The objective of this paper is to describe urinary cotinine levels in tobacco farmers.

Methods A cross-sectional study was conducted in 2570 tobacco farmers. All participants that report GTS in the week prior to the interview plus a subsample of 492 pesticide applicators were included. Urinary samples and information about socio-demographic, behavioural, dietary, occupational characteristics and pesticide poisoning during lifetime were collected. Stratification by sex and smoking was performed and Wilcoxon and Kruskal-Wallis non-parametrical tests were used to analyse cotinine means.

Results 582 individuals were analysed. There was no difference in urinary cotinine means between GTS symptomatic and asymptomatic individuals. Among non-smokers, having picked tobacco in the previous week was associated with higher cotinine means in both sexes. Cotinine levels were higher on the first day of symptoms and reduced exponentially with each day in female non-smokers. Male non-smokers had higher levels on the second day and the reduction was more gradual. The cotinine level rose up to 15 cigarettes/day of consumption.

Conclusion The urinary cotinine measures exposure to nicotine up to its saturation point; while GTS, affected by tolerance, indicates nicotine poisoning. Strategies to reduce nicotine exposure in tobacco production are needed. Mechanisation to be used in rough ground and which guarantee leaf quality could be an alternative. More studies are needed to evaluate the chronic effect of nicotine exposure.