Human biomonitoring : biomarkers, individual susceptibility, and nutrigenetics

Tese de doutoramento, Biologia (Genética), Universidade de Lisboa, Faculdade de Ciências, 2015

Cytokinesis blocked micronucleus (CBMN) assay and comet assay are the most promising short-term genotoxicity assays for human risk assessment and their combination is recommended to monitor populations chronically exposed to genotoxic agents. Nutrition is recognized to be an important lifestyle factor that influences cancer risk, and should be taken into account at an individual level. Laboratories are occupational settings where chemical agents are handled and workers are exposed. Formaldehyde and cytostatic drugs, in particular, are chemical agents handled in laboratories that are considered carcinogenic for humans and special protective measures should thus be adopted against them. The aim of this investigation is to contribute to the development of a biomonitoring programme that includes genotoxicity assessment related with genetic susceptibility biomarkers, and lifestyle factors, namely nutrition. The experimental planning used was a case-control blinded study. Four separated samples were formed comprising two samples of subjects exposed (n = 56 for formaldehyde; n = 46 for cytostatics), and two samples of non-exposed controls (n = 85 and n = 46, respectively). Participants filled-in a personal and a food frequency questionnaires. CBMN and comet assays were used to assess genotoxicity. Individual susceptibility was investigated by Real Time PCR. Measurements of serum vitamins A and E were performed by HPLC, and vitamin D by ELISA. The risk of genotoxicity in those exposed was then compared with the risk in the controls, allowing for the quantitative measurement of association between exposure and genotoxicity. In both occupational settings, the genotoxicity biomarkers were significantly higher in the exposed than in the non-exposed controls (p<0.05). In the formaldehyde occupational context, significant associations were found between XRCC3 genotypes and nuclear buds; but that was not the case either for ADH5 or VDR. Comet assay did not identify significant differences between those exposed to cytostatics and controls, and the same lack of association applies to the OGG1 genotypes. Micronutrients association to the genotoxicity biomarkers was controversial; we have found positive correlations for vitamin A and negative ones for vitamin E. Our findings emphasize the need for the implementation of a regular biomonitoring programme of personnel occupationally exposed to drugs like formaldehyde and cytostatics.

Fundação para a Ciência e a Tecnologia, IP (FCT)