Exposure assesment to bisphenols: combining biomonitoring and duplicate diet studies
- Autores: Nieves González Paradell
- Directores de la Tesis: Montse Marquès Bueno (dir. tes.), José Luis Domingo Roig (dir. tes.), Martí Nadal Lomas (dir. tes.)
- Lectura: En la Universitat Rovira i Virgili ( España ) en 2020
- Idioma: español
- Tribunal Calificador de la Tesis: Francisco García Sayago (presid.), Jordi Sierra Llopart (secret.), Nuno Ratola (voc.)
- Programa de doctorado: Programa de Doctorado en Biomedicina por la Universidad Rovira i Virgili
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Bisphenols (BPs) are a group of organic compounds that are used in many consumer products. The most important source of exposure in humans is through the consumption of foodstuffs, either canned or packed in polycarbonate plastic. Among all the BPs, bisphenol A (BPA) is the most used analogue in the industry, being also ubiquitously present in the environment. The endocrine disrupting potential of BPA has been largely demonstrated, while other adverse health effects, such as reproductive, developmental or fertility problems are linked to its exposure. Therefore, regulation against BPA is getting stricter throughout the world. In this sense, manufacturers started to replace BPA by other BP analogues. Nonetheless, similar or even greater endocrine-disrupting capacity has been reported for some alternative analogues.
Biomonitoring studies consist in analysing target compounds or metabolites in biological samples, being an effective strategy to assess the exposure to BPs. In addition, the analysis of BPs in food samples is suitable to accurately estimate the real exposure to BPs, considering that the diet is the main exposure pathway. This approach is frequently tackled through duplicate diet studies, which consist in collecting two food portions: one for chemical analysis and the other for consumption.
The present doctoral thesis was aimed at assessing the dietary exposure to BPs in a general population cohort by means of a duplicate diet study of canned food.
In Chapter 1, the optimization and validation of the analytical method was carried out. The procedure of extraction and derivatization of BP analogues in biological tissues (blood) was therefore optimized. Different parameters were tested to enhance the quantification of the chromatographic peaks of BPs including sample volumes, the addition of salts or derivatizing agents. Results showed that gas chromatography – mass spectrometry (GC-MS) is an appropriate analytical technique for most of BP analogues. However, for some analogues (namely BPS) the analysis through GC-MS might not be the most optimal procedure.
In Chapter 2, the dietary exposure to BPs was assessed by analysing their co-occurrence in food. A number of foodstuffs including canned food, fresh products or food packed in other BP-free materials, were included. Among 8 BPs analogues, only BPA, BPE and BPB were detected, being BPA the most abundant compound. Importantly, one sample of canned asparagus presented BPA levels above the specific migration limit (SML) established by the European Commission. Unexpectedly, BPs were also reported for non-canned food, being food processing a potential contamination source. Anyhow, the estimated dietary intake of BPA by an adult consuming a canned food diet was below the tolerable daily intake (TDI) established by the European Food Safety Authority (EFSA).
Finally, in Chapter 3, the content of BPs in biological samples of the volunteers who participated in the duplicate diet study was analysed by applying the method optimized and validated in Chapter 1. Biological samples were urine and blood (whole blood, plasma and red blood cell (RBC) fractions) collected for 2 days of study. As expected, urine was reported as the best matrix to carry out biomonitoring of BPs due to the fast metabolism and excretion of these compounds. BPA was detected in most urine samples, for both groups, either exposed and control. Anyhow, concentrations of BPA in urine of the exposed group were significantly higher than in the control group. Other BP analogues were only found at trace quantities in few random samples, being hardly correlated to the consumption of canned food and their use as BPA substitutes. These results confirm that diets based on canned food significantly increases the exposure to BPA, but not to other BP analogues. Since spot urine sample, instead of 24-h composites, were collected, it could be confirmed that the shorter intervals of urine sampling the better the exposure to BPA is predicted, being successfully correlated with the dietary ingestion of BPA. Thus, 4-h interval was found to be an optimal interval. Finally, the exposure to BPA was calculated considering the concentrations of BPA in urine. Results are similar to the dietary exposure predicted in Chapter 2, representing less than the 3% of the TDI. Consequently, the low exposure to BPA means that no harmful effects are likely to occur in humans, even when consuming a diet of canned food.
Summarizing, BPA is here reported to be ubiquitously present in foodstuffs, regardless the food packaging. However, BPA content is higher in canned foodstuffs than fresh or glass-packed food. Therefore, the consumption of canned food leads to a higher exposure to BPA, although the TDI is not exceeded, even when following a canned food diet. Interestingly, the occurrence of other analogues in food and urine is hardly linked to the intake of canned foodstuffs, and the use of personal care products and thermal paper could be other potential sources. Anyhow, the potential increasing occurrence of other unregulated BPs might mean a significant exposure to BPs in the future, considering the potential endocrine-disrupting effects of these chemicals, the regulation of not only BPA but also other analogues is mandatory.
