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The increasing awareness of our surrounding environment as a source of human exposure to a large number of known and unknown chemicals and the adoption of the exposome concept is promoting a growing interest in holistic approaches that allow a more comprehensive assessment of contaminants in the investigated matrices. In most instances, these types of analyses rely on the improved chromatographic and/or mass spectral resolution provided by the instrumental techniques selected for the final analytical characterization of the study extracts. In this study, the enhanced separation power and identification capabilities offered by comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC¿ToF MS) has been used for the identification and annotation of organic pollutants of different nature in sediments collected in a contaminated area near Madrid. The samples were collected in the spring of 2017, after the explosion of the distillation reactor of a company dedicated to the recovery of solvents and recycling of industrial waste and the subsequent uncontrolled fire of the facility. The results evidenced a generalized contamination in the area and that the pollutants have reached the water table. Acknowledgements. This work is part of the I+D+i project PID2019-106405GB-I00 financed by MCIN/ AEI/10.13039/501100011033.

Bisphenol A (BPA) is a well-known endocrine-disrupting compound (EDC) whose use is regulated [1] and, in some cases, restricted [2] by the European Union. Due to these actions, manufacturers are switching to other substitutes, with a similar structure to BPA, to be used in different applications, such as bisphenol B (BPB), bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), fluorene-9-bisphenol (BHPF), bisphenol Z (BPZ) and tetramethyl bisphenol F (TMBPF). However, several studies have demonstrated that all of them also exhibit endocrine-disrupting properties [3]. Within a regular diet, fluid intake is one of the most important factors for correct hydration and healthy state of the individual, being water and soft drinks the greatest contributors of fluids through the diet for the adult population [4]. Therefore, these drinks have special relevance in studies on estimating the intake of EDCs from food contact materials (FCMs) such as cans and plastic bottles. For all these reasons, it is necessary to develop analytical protocols that allow the multi-residue determination of BPA and its substitutes in water and soft drinks usually consumed by the general population. A fast and multi-residue method based on ultra-high performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ) has been optimized and characterized in terms of linearity, precision and limit of detection and quantification. Besides, different solid-phase extraction (SPE) conditions have been tested to achieve the quantitative extraction of the eight-targeted bisphenols in water and soft drink samples. Acknowledgement: Authors thank the Spanish Ministry of Science and Innovation and the Spanish State Research Agency (PID2019-106405GB-I00/AE/10.13039/501100011033) and the Comunidad of Madrid and European funding from FSE and FEDER programs (S2018/BAA-4393, AVANSECAL-II-CM) for financial support. C. Fernández-Ramos thanks Consejería de Educación e Investigación de la Comunidad de Madrid and FSE program for his grant (CAM19_PRE_IQOG_001). References: [1] Commission regulation (EU) No 10/2011 of 14 January 2011 on Plastic materials and articles intended to come into contact with food. [2] Commission Directive 2011/8/EU of 28 January 2011 amending Directive 2002/72/EC as regards the restriction of use of Bisphenol A in plastic infant feeding bottles. [3] S.P. den Braver-Sewradj et al., Crit. Rev. Toxicol. 50 (2020). [4] I. Guelinckx, et al., Eur. J. Nutr. 54 Suppl (2) (2015)., Authors thank the Spanish Ministry of Science and Innovation and the Spanish State Research Agency (PID2019-106405GB-I00/AE/10.13039/501100011033) and the Comunidad of Madrid and European funding from FSE and FEDER programs (S2018/BAA-4393, AVANSECAL-II-CM) for financial support. C. Fernández-Ramos thanks Consejería de Educación e Investigación de la Comunidad de Madrid and FSE program for his grant (CAM19_PRE_IQOG_001)

24 Páginas.-- 2 Figuras, Emerging and re-emerging food safety risks are driven by climate change and other factors like globalization, water scarcity, population aging, and migration, among others. These factors affect the persistence and occurrence of conventional and emerging primary risks. Successful initiatives to manage emerging risks need to identify, evaluate, and prioritize potential risks as well as to respond with sustainable strategies able to reduce the threats

The amount and number of synthetic chemicals in use has significantly increased over the last decades. Many of these compounds have been demonstrated to be able to reach and distribute in the environment [1]. National and international environmental monitoring programs are constantly updated to include new chemicals with persistent, bioaccumulative and toxic (PBT) characteristics. However, a large number of chemical substances in wide commercial use are still not measured in environmental samples on a regular basis, and their environmental fate remains unknown. The increasing awareness of our surrounding environment as a source of human exposure to a large number of known and unknown chemicals and the adoption of the exposome concept has led to an interest in holistic approaches that allow a more comprehensive assessment of contaminants in the environmental matrices. Despite the inherent complexity of these types of approaches, from an analytical point of view, the technological and instrumental advances of the last decades have enabled a significant progress in this research field. Such an increasingly holistic characterization typically relies on the enhanced chromatographic [2] and/or mass spectral resolution [3] of the instrumental techniques selected for final analytical characterization of the investigated samples. This study evaluates the feasibility of comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC¿ToF MS) for the suspect and non-target screening (NTS) of organic compounds in complex environmental matrices. In particular, the enhanced separation power and characterization capabilities of GC×GC¿ToF MS have been used for the identification and annotation of organic pollutants of a widely divergent chemical nature in sediments collected in a contaminated area close to Madrid. Samples were collected in spring 2017, after the explosion of the distillation reactor of a company dedicated to solvent recovery and recycling of industrial wastes and the subsequent uncontrolled fire of the installation. Acknowledgements Authors thank the Spanish Ministry of Science and Innovation and Spanish State Research Agency (PID2019-106405GB-I00 / AEI / 10.13039/501100011033) and the Comunidad of Madrid and European funding from FSE and FEDER programs (S2018/BAA-4393, AVANSECAL-II-CM) for financial support. References [1] D.C.G. Muir, P.H. Howard, Environ. Sci. Technol. 40 (2006) 7157-7166. [2] J. Escobar, S. Mekni, G. Blanco, E. Eljarrat, D. Barceló, L. Ramos, J. Chromatogr. A 1536 (2018) 163-175. [3] A.C. Chiaira_Hernández, M. Scheringer, A. Müller, et al., Sci. Total Environ. 740 (2020) 140181., Authors thank the Spanish Ministry of Science and Innovation and Spanish State Research Agency (PID2019-106405GB-I00 / AEI / 10.13039/501100011033) and the Comunidad of Madrid and European funding from FSE and FEDER programs (S2018/BAA-4393, AVANSECAL-II-CM) for financial support.

Dietary supplements are increasingly being consumed in developed countries for different purposes. The high incidence of obesity and overweight problems in these societies [1], combined with the rise of specific aesthetic canons, have made nutritional supplements, marketed as aids for weight control, to be increasingly consumed by general population. Among them, those produced from vegetable sources are particularly well accepted because they are perceived as natural and, consequently, harmless products. However, some of these dietary supplements have been involved in several food and medical alerts and incidents due to the presence of contaminants and/or adulterants in their formulations, as well as misleading or incorrect labelling [2]. In many cases, the medical consequences derived from the uncontrolled presence of undesirable or not declared compounds are worsened by the fact that the consumption of these dietary supplements is often not controlled by a healthcare professional. During the last decade, the possibility of acquiring these types of plant-based supplements from third countries (often from not clearly identified or unknown producers) through the open internet market has contributed to aggravate the problem. Safety and quality control of dietary supplements manufactured in developed countries or subjected to regular importation processes is guaranteed by current legislations. In general, these routine analytical controls are considered laborious and expensive in terms of time and reagents consumption because they usually involve separate analytical determinations for the different classes of compounds to be controlled, e.g. plant bioactives, adulterants, pharmaceuticals and contaminants. Meanwhile, products received from third countries by alternative channels frequently escape these exhaustive analytical determinations. The aim on this study was the setting-up of a workflow that allowed the efficient, integrated and simplified analytical control of the previously mentioned groups of organic compounds in plant-based dietary supplements with minimum sample manipulation and reagent consumption. This poster summarizes the analytical strategy followed to implement the analysis of contaminants in such workflow. Satisfactory results demonstrate the general validity of the proposed approach for the generic screening of micro-contaminants through application to plant-based dietary supplements of different nature and from different sources and allowed to identify plasticizers as the main toxicants present in the investigated samples. Acknowledgements Authors thank the Spanish Ministry of Science and Innovation and Spanish State Research Agency (projects reference PID2019-106405GB-I00/AEI/10.13039/501100011033 and AGL2016-80475-R) and the Comunidad of Madrid and European funding from FSE and FEDER programs (project reference S2018/BAA-4393, AVANSECAL-II-CM) for financial support. References [1] OECD (2010), Obesity and the economics of prevention: Fit not fat, OECD Publishing, Paris, https://doi.org/10.1787/9789264084865-en. [Last access: January 2021]. [2] NIH (2019), Dietary supplements for weight loss. U.S. Department of Health and Human Services. https://ods.od.nih.gov/factsheets/WeightLoss-Consumer/ [Last access: January 2021]. [3] A. Mena-García, S. Rodríguez-Sánchez, A.I. Ruiz-Matute, M.L. Sanz. Exploitation of artichoke byproducts to obtain bioactive extracts enriched in inositols and caffeoylquinic acids by microwave assisted extraction, J. Chromatogr. A 1613 (2020) 460703., Authors thank the Spanish Ministry of Science and Innovation and Spanish State Research Agency (projects reference PID2019-106405GB-I00/AEI/10.13039/501100011033 and AGL2016-80475-R) and the Comunidad of Madrid and European funding from FSE and FEDER programs (project reference S2018/BAA-4393, AVANSECAL-II-CM) for financial support.

CSIC Scientific Challenges: Towards 2030, That epigenetic changes during lifetime (i.e. those with a biological purpose, epigenetic drift and epigenetic clocks) depend on a complex mixture of factors is well-known, as is the fact that, depending on the loci, they can be modulated by genetic and/or external factors, lifestyle being one of the most important. However, the underlying molecular mechanism remains largely unknown and addressing this will be an important challenge for CSIC in this field.

Author thanks MICINN, Comunidad of Madrid and European funding from FSE and FEDER for projects AGL2016-80475-R and S2018/BAA-4393 (AVANSECAL-II-CM)

XVIII Scientific Meeting of the Spanish Society of Chromatography and Related: XVIII Reunión de la Sociedad Española de Cromatografía yTécnicas Afines (SECyTA 2018), del 02-04 de Octubre de 2018 en Granada (España) .-http://wpd.ugr.es/~secyta2018/, Iodine is a ubiquitous element that can be found widespread in living organisms, Earth's crust, atmosphere, and especially, seawater. Atmospheric iodine plays a relevant role in climate change, modifying the oxidative capacity of the troposphere through a number of processes, including the depletion of ozone by catalytic cycles. Bearing in mind that most of this iodine comes from the oceans, analytical methods capable of detecting and quantifying iodine in seawater are necessary. However, this is a challenging matrix because iodine species (iodide and iodate) concentration extends over several orders of magnitude and high concentrations of other anions and cations are also present. These facts make difficult to get reliable values with most of common analytical methodologies.

XIV Congreso Luso-Español de Herpetología - XVIII Congreso Español de Herpetología (2016), bajo el lema Retos de la Herpetología en el Siglo XXI y celebrado en la Universidad de Lleida, entre los días 5 y 8 de octubre de 2016

Trabajo presentado a la XV Reunión científica de la Sociedad Española de Cromatografía y Técnicas Afines - SECyTA 2015. Castellón de la Plana, 27-30 de octubre de 2015., Endocrine disruptors (ECD, Endocrine Disrupting Chemicals) are chemicals that may interfere with the body’s endocrine system and produce adverse developmental, reproductive, neurological, and immune effects in both humans and wildlife[1]. Due to this, it has been necessary to develop rapid and sensitive method for the determination of ECD. This work presents the results of the analysis of four phthalates[2] (PAEs: dimethyl phthalate, diethyl phthalate, dibutyl phthalate and butyl benzyl phthalate), seven parabens[3] (PBs: methyl paraben, ethyl paraben, n-propyl paraben, iso-propyl paraben, n-butyl paraben, iso-butyl paraben and benzyl paraben) and bisphenol A[4] (BPA) in 42 commercially available milk samples, related to the packaging and storage. Because of contamination problems, a method based on the simultaneous extraction and purification of the sample, was chosen to reduce the manipulation[5]. Briefly, extraction in glass column was carried out by matrix solid phase dispersion (MSPD) put on a layer of Florisil® (purification). The column was eluted with ethyl acetate and concentrated for its final quantification by ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). With this method, all the analyte recoveries were higher than 70%. Different brands (11 commercial trademarks) and different types of containers (metallic bag, metal pail, HDPE, PET, Combibloc®, Tetra Brick®, Tetra Gemina® and Tetra Prisma®) have been investigated to study the effect of the container and the possible contamination during the production and processing of the product. The concentration levels and profiles found (expressed as median in pg/g fresh weight) were different for each type of analyte. PBs showed the highest concentration (1564 – 42879 pg/g f.w.), followed by PAEs (2810 – 9094 pg/g f.w.). Finally, BPA showed the lowest concentration (7 – 13 pg /g f.w.). Depending on the type of packaging, the highest PAE concentrations were found for metal pail and carton packages (which incorporate on their inside four layers of polyethylene which protects the content from the exterior moisture). Regarding BPA, the highest concentration was found for HDPE containers (high density polyethylene ). Finally, the highest PB concentrations were obtained for those milk samples packed in PET bottles (polyethylene terephthalate ). However, to the best of our knowledge, this fact seems to be more related with the nature of these samples (fresh milk, not UHT milk) than with the container itself. [1] Commission of the European Communities. Brussels, COM 706 (1999) [2] T. Schettler, Int. J. Androl. 29 (2006) 134-139 [3] A. Ballesteros-Gómez, JCA 1216 (2009) 449-469 [4] L. Brimer, Chemical Food Safety 24 (2011) Cap 24 [5] M. Llompart, JCA 1293 (2013) 10-19 Acknowledgements: Authors thank the Spanish Ministry of Economy and Competitiveness (project AGL2012- 37201), Comunidad Autónoma of Madrid (Spain) and European funding from FEDER programme (project S2013/ ABI-3028, AVANSECAL) for its financial support, Mrs. Sagrario Calvarro for instrumental maintenance and control and Mr. Luis A. Muñoz for his help., MINECO AGL2012-37201; Fondos FEDER y Comunidad de Madrid (S2013/ABI-3028, AVANSECAL)

Trabajo presentado a la XV Reunión científica de la Sociedad Española de Cromatografía y Técnicas Afines - SECyTA 2015. Castellón de la Plana, 27-30 de octubre de 2015., Honey is a natural product produced by Apis mellifera bees from the nectar or secretions of plants, and has been consumed by many people around the world as a natural food, in medical therapies, and as food supplements [1]. Polychlorinated biphenyls (PCBs) are a family of toxic and persistent organic pollutants that are present in food an environmental samples at different concentrations levels. For the general population, dietary intake is the main route of PCB exposure, contributing with more than 90% to daily exposure [2]. Some PCB congeners are toxic to humans, and the European Commission has recently established maximum permissible levels of dioxin-like PCBs (DL-PCBs) in foods [3]. Twenty PCB congeners (# 28, 52, 77, 81, 101, 105, 114, 118, 123, 126, 138, 153, 156, 157, 167, 169, 170, 180, 189, and 194), including non-ortho, mono-ortho, and the most abundant PCBs were determined in 35 commercially available honeys collected between 2010 and 2012 in Brazil (n=16), Spain (n=10), Portugal (n=4), Slovenia (n=4), and Morocco (n=3). The analytical procedure followed was previously validated by the working group and briefly consists on liquid-liquid extraction followed by a clean-up step carried out using a multilayer column filled with neutral, acid, and basic modified silica. The final instrumental determination was carried out by GC-QqQ(MS/MS), using the isotope dilution technique as quantification method [4]. The results reveal the presence of low amounts of all PCB congeners (between, Ministerio de Economía y Competitividad, Comunidad de Madrid, European Commission

Trabajo presentado al EURO FOOD CHEM XVIII, celebrado en Madrid los días 13 a 16 de octubre de 2015, Food products are produced and distributed worldwide, so leading to very stringent regulations to guarantee food quality safety. Comparison of the various sources of food contamination with organic chemicals suggests that among the public, but also among experts, the perception of risk is often distorted. Therefore, if you ask educated consumers about the principal source of food contamination they will list pesticides as the first item, just few of them would even mention food-packaging materials, although the amount of material migrating from food packaging into food may well be 100 times greater than the contribution of pesticides or environmental pollutants [1]. Plasticizers have been described as being among the most abundant man-made environmental pollutants. Among them, phthalates and other plasticizers have been focus at several surveys and exposure assessments. In addition, bisphenols, such as bisphenol A (BPA), and their derivates with epoxy or clorohydrin groups are known to be endocrine disruptors in humans as well as being potentially carcinogenic [2]. A rapid and sensitive analytical method based on ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) has been developed for the determination of different food contaminant coming from packaging materials. All the analyses were performed using an Acquity UPLC© BEH Phenyl column (2.1 mm x 50 mm, 1.7 μm, Waters), and the compounds were subsequently analyzed by a Xevo© TQ-S triple quadrupole mass spectrometer (Waters) using an electrospray ionization (ESI) interface. Optimal UHPLC-MS conditions were selected based on sensitivity, selectivity and reproducibility terms. Two transitions for each analyte and isotopically labeled internal standard were monitored in multiple reaction monitoring (MRM) mode. Specific transitions from different precursor to several product ions were studied and the most abundant one was chosen for quantification and the second most abundant for confirmation. This methodology was applied to the study of the influence of main domestic parameter related to storing and cooking such as time, temperature and plastic type material. The results show a clear relationship of dependence between these three experimental parameters and phenomena of migration of this type of contaminants from the container. For doing these experiments, the different food simulants established in the Official Journal of European Union [3] were employed. Acknowledgments Spanish Ministry of Economy and Competitiveness (project AGL2012-37201) JCCM (Postdoctoral contract Resolución de 08/08/2014) References: (1) Gallarta-Ayala H, Núñez O, Lucci P. (2013) Recent advances in LC-MS analysis of food-packaging contaminants. TRAC-Trends Anal Chem 42, 99-124. (2) Poças MF, Hogg T. (2007) Exposure assessment of chemicals from packaging materials in foods: a review. Trends Food Sci Tech 18, 219-230. (3) COMMISSION REGULATION (EU) No 10/2011of 14 January 2011. Official Journal of European Union., Acknowledgments Spanish Ministry of Economy and Competitiveness (project AGL2012-37201) JCCM (Postdoctoral contract Resolución de 08/08/2014)

Trabajo presentado a la XV Reunión científica de la Sociedad Española de Cromatografía y Técnicas Afines - SECyTA 2015. Castellón de la Plana, 27-30 de octubre de 2015., Phthalates (diesters of 1,2-benzenedicarboxylic acid), also known as phthalic acid esters (PAEs), are synthetic organic compounds that are used in a broad spectrum of industrial and commercial applications, like toys, food packaging, lubricants, vinyl flooring, adhesives, detergents, hair spray, shampoo, etc. [1] . They have endocrine disrupting potency and have become nearly ubiquitous. For the general population, the human exposure to phthalates is through ingestion, inhalation, dermal absorption, and/or contact with medical devices [2]. Once they are ingested, PAEs are rapidly metabolized to their respective monoesters in human body and some of these primary metabolites can be further metabolized to secondary metabolites and excreted by urine. All of these metabolites can be used as biomarkers of human exposure to phthalates [3]. The sample preparation and instrumental determination methods have been previously described elsewhere [4]. Briefly, the sample preparation consisted of an enzymatic deconjugation of the glucuronide phthalates followed by a purification step with OASIS© HLB SPE cartridge (Waters, MA, USA). The instrumental determination was carried out by using UPLC QqQ MS2 (Xevo-TQS, Waters) working in MRM mode, with a BEH-phenyl column (50 mm x 2.1 mm, 1.7 µm),. We present here, for the first time, the levels and temporal trends of 9 PAE metabolites (6 phthalate monoesters (monomethyl phthalate [MMP], monoethyl phthalate [MEP], mono-iso-buthyl phthalate [MiBP], mono-n-butyl phthalate [MBP], monobenzyl phthalate [MBzP] and monoethylhexyl phthalate [MEHP]) and 3 secondary metabolites of DEHP (5-OH-mono(2-ethylhexyl) phthalate [5-OH-MEHP], 5-oxo-mono(2-ethylhexyl) phthalate [5oxo-MEHP] and 5-carboxy-mono(2-ethylpentyl) phthalate [5cx-MEPP]) in human urine samples collected in 2012 and 2015 from 9 volunteers living in the Community of Madrid. Detectable amounts of the 9 MPAEs were obtained in all the studied samples, being the MPAE levels found in almost all collected in 2012 slightly lower than those found three years later (2015). [1] T. Schettler. Int. J. Androl. 29 (2006) 134-139. [2] R. Hauser, A. Calafat. Occup. Environ. Med. 62 (2005) 806–818. [3] H. Frederiksen, S.K. Kranich. Environ. Sci. Technol. 47 (2013) 958–967. [4] L. Herrero, S. Calvarro. Anal Chim Acta 853 (2015) 625–636. Acknowledgements: Authors wish to thank all the volunteers who have donated samples and Paula Chamorro and Héctor Carrascosa for their laboratory work. Financial support was obtained from the Spanish Ministry of Economy and Competitiveness (project AGL2012-37201) and the Comunidad Autónoma of Madrid and European funding from FEDER program (projects S2009/AGR-1464, ANALISYC-II and S2013/ABI-3028, AVANSECAL)., MINECO (AGL2012-37201), Fondos FEDER y Comunidad de Madrid (S2009/AGR-1464, ANALISYC-II y S2013/ABI-3028, AVANSECAL)

Trabajo presentado a la XV Reunión científica de la Sociedad Española de Cromatografía y Técnicas Afines - SECyTA 2015. Castellón de la Plana, 27-30 de octubre de 2015., Gas chromatographs coupled to mass spectrometers (GC-MS) have been extensively applied for the determination of volatile and semi-volatile, non-polar, compounds in fields like food safety, environmental or toxicological studies. Most methods reported in the literature use electron ionization (EI) [1], which may result in extensive fragmentation of analytes compromising both, selectivity and sensitivity. This makes also difficult the application of tandem MS due to lack of specific/abundant precursor ions [2]. The analysis of persistent organic pollutants, including brominated flame retardants (BFRs), polychlorinated dibenzodioxins, polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls (dl-PCBs), relies on the use of methods based on GC-MS operating in EI or negative chemical ionization (NCI) modes using quadrupole, triple quadrupole, ion trap or magnetic sector analyzers [3]. These halogenated contaminants are examples of compounds for which a softer, reproducible and robust ionization technique might be favorable since they show high fragmentation in EI and low specificity in NCI [4]. In this work the potential of atmospheric pressure chemical ionization (APCI) combined with GC and triple quadrupole mass analyzer has been investigated, using BFRs, PCDD/PCDF and dl-PCBs as model compounds for their determination in different complex samples, including marine samples, milk, feed and animal fat and interlaboratory studies samples. Ionization and fragmentation behavior of 14 PBDEs and 3 novel BFRs as well as 10 PCDD/PCDF and 7 dl-PCB congeners by APCI has been studied. The formation of highly abundant (quasi) molecular ions has been the main goal because of the expected improvement in specificity obtained when using it as precursor ion in tandem MS. The convenience of using modifiers for the ionization step has been studied and discussed for each family of compounds with the aim of obtaining the maximum sensitivity in combination of acceptable reproducibility and optimum specificity/selectivity. The improved detectability (LODs between 1 and 20 fg) achieved when using APCI compared to EI has been demonstrated. The application to different complex samples has shown the feasibility of the methods at trace levels for unambiguous identification and determination of the compounds investigated. These results highlight the potential of APCI as the reference for quantification of halogenated pollutants in the next years. [1] J. Cristale, J. Chromatogr. A. 1241 (2012) 1–12. [2] D. Wang, Mass Spectrom. Rev. 29 (2010) 737–75. [3] B. Gómara, Anal. Chim. Acta. 597 (2007) 121–8. [4] H.M. Stapleton, Anal. Bioanal. Chem. 386 (2006) 807–817.

CSIC, CM, INIA, CICYT (Spanish institutions) for financial support.

Organochlorine compounds such as polychlorinated biphenyls (PCBs) and dichlorodiphenyl ethanes (DDTs) are well known as toxic and persistent contaminants that accumulate in the trophic levels of food chains, apparently associated with the habitat and dietary habits. In recent years there has been an increasing concern for these chemicals mainly due to their estrogenic properties. In many oviparous species, PCB pollution can produce severe impacts on eggs leading to embryo death or abnormal embryonic development. It is reported that pollutants can severely affect reptiles and could be contributing to their global decline., The authors would like to thank Junta de Andalucía and CSIC for financial support.