Pedro M. Félix

Fifteen years of nuclear techniques application to suspended particulate matter studies

Acute and chronic exposures to Airborne Particulate Matter (APM) have been linked, in epidemiological studies, to increased mortality and to a wide spectrum of respiratory and cardiovascular disorders. One factor that highly influences the toxicity of APM is its chemical composition. Nuclear Analytical Techniques (NATs) can be advantageously used in the determination of the particles element composition due to their multielement capability in association with low detection limits. Therefore, the characterization of APM by these techniques contributes to the identification of emission sources and, consequently, to the assessment of the effectiveness of the current air pollution abatement strategies. The main goal of this paper was to present the achievements obtained within 15xa0years of activities related with the use of NATs on the analysis of APM sampled in outdoor, indoor and industrial environments. The results presented in this work confirmed the relevance of NATs as efficient analytical techniques not only in the characterization of APM, but also in source apportionment, identification of long range transport and health assessment studies.

Assessment of exposure to metals in lead processing industries.

Inhalation of particulate matter in industrial environments has been associated with respiratory symptoms and lung diseases, which continues to lead to long- and short-term hazardous health effects on exposed subjects. The main objectives of this study were (a) to determine the dust exposure of workers from the lead industry in different operations and (b) to evaluate if the Exhaled Breath Condensate (EBC) can be used as a non-invasive tool to evaluate this exposure. Therefore, this cross-sectional study not only measured the exposure to Airborne Particulate Matter (APM) and to the associated elements but also analysed the EBC elemental composition. APM was collected in Ind1, Ind2, Offices and outdoor with Gent samplers, which delivers two size fractions: fine particulate matter (< 2.5 μm), and coarse particulate matter (between 2.5 and 10 μm). EBC samples were collected from the workers and from a non-exposed group working in Offices. The techniques INAA and PIXE were used for the APM element characterization and ICP-MS for EBC elemental content. The PM2.5 and PM2.5-10 mass concentrations were significantly higher in the industries studied than in Offices and in the environment. At the industrial sites surveyed the coarse fraction dominated and both factories had different fingerprints: APM elements with higher expression were Pb, Sb, Na, Cl and Fe in Ind1 and Pb, Si, Br, Ca, Al, Cl and Na in Ind2. Most of these elements revealed a gradient of concentration where Ind.1 > Ind.2 > Offices and EBC revealed a clear translation of this exposure, suggesting the latter to be a potential good indicator of exposure to metals in occupational settings. Pb in EBC presented the most representative results. Even though EBC was found to reflect predominantly the inhaled coarser fraction it is more related to concentration levels of exposure than to the predominance of APM fraction. The present study demonstrated not only the ability of EBC to reflect environmental exposure to metals but also the importance of measuring and characterizing different fractions of APM for a correct assessment.

Biomarkers of Exposure to Metal Dust in Exhaled Breath Condensate: Methodology Optimization

ABSTRACT In occupational assessments where workers are exposed to metal dust, the liquid condensate of exhaled breath (EBC) may provide unique indication of pulmonary exposure. The main goal of this study was to demonstrate the quality of EBC to biological monitoring of human exposure. A pilot study was performed in a group of metal dust–exposed workers and a group of nonexposed individuals working in offices. Only metal dust–exposed workers were followed along the working week to determine the best time of collection. Metal analyses were performed with inductively coupled plasma mass spectrometry (ICP-MS). Analytical methodology was tested using an EBC sample pool for several occupationally exposed metals: potassium, chromium, manganese, copper, zinc, strontium, cadmium, antimony, and lead. Metal contents in EBC of exposed workers were higher than controls at the beginning of the shift and remained augmented throughout the working week. The results obtained support the establishment of EBC as an indicator of pulmonary exposure to metals.

Using the exhaled breath condensate as a tool for non-invasive evaluation of pollutant exposure

The aim of the present study was to investigate whether Exhaled Breath Condensate (EBC) can be employed for a better risk assessment among human exposure to heavy metals. The objective was to develop a human bioindicator to be applicable for professional exposure that, compared with other common indicators, presents important advantages: it is non-invasive and it is easily and quickly collected. EBC was sampled in industrial workers and in a control group consisting of healthy volunteers working in offices. Heavy metal concentrations in EBC were determined by Total Reflection X-Ray Fluorescence (TXRF) in parallel low-volume samplers, and the techniques Particle Induced X-ray Emission (PIXE) and Instrumental Neutron Activation Analysis (INAA) were used to characterise air particulate matter in the factory and in the offices. Results revealed that Pb and Cu were significantly higher in industrial workers EBC, raising the possibility of using this new matrix in occupational settings in order to assess the workers exposure to toxic agents.

Exhaled breath condensate as a biomonitor for metal exposure: a new analytical challenge

The study of exhaled breath condensate (EBC) obtained by cooling exhaled air under conditions of spontaneous breathing is considered one of the areas with higher interest in respiratory health research. The use of EBC for elemental determination in occupational exposure requires a standard methodological procedure to implement its practice in occupational studies. EBC is an inhomogeneous sample with organic and particulate matter in suspension, which may hamper analytical results reliability. Total reflection X-ray fluorescence and inductive coupled-plasma mass spectrometry (ICP-MS) techniques were chosen as both are multielemental, require small sample volumes and have appropriate detection limits. Estimation of the overall uncertainty in both techniques was carried out using a pool of EBC collected from a group of workers of a lead processing industry to perform precision and trueness studies for K, Mn, Cu, Cd, Sb and Pb. Precision was estimated in terms of repeatability using the native EBC sample pool and trueness in terms of recovery obtained from spiking aliquots of the EBC pool with K, Mn, Cu, Cd, Sb and Pb at different concentrations. Recovery was the most significant contribution to total uncertainty. The overall uncertainties obtained for ICP-MS enabled to discriminate between groups of individuals exposed to different levels of contaminants. Therefore EBC proved to be useful in human biomonitoring.

Impact of freshwater inputs on the spatial structure of benthic macroinvertebrate communities in two landlocked coastal lagoons

Landlocked lagoons are naturally stressed environments. They are strongly influenced by freshwater input which not only varies naturally, but which is also impacted by anthropogenic activities. This study investigated the direct influence of freshwater discharges on the distribution patterns and abundance of benthic communities in two neighbouring landlocked coastal lagoons, assessing the whole system and the confluence area of each tributary. Sampling occurred in the wet and dry seasons of 2011 at two distances from freshwater discharge locations. Both lagoons were colonized by species from two different pools, freshwater and marine. Freshwater flow rates had a direct influence on the spatial structure of the benthic communities of brackish-water/freshwater interface areas, where also specific taxa can act as early indicators of freshwater input variations. The intensity of this influence is highly dependent on lagoon size, creating spatial heterogeneity or affecting the entire system. The benthic fauna at the confluence of the tributary that depends almost exclusively on groundwater showed the lowest variability, suggesting that the biogeochemical nature of the groundwater may be a central cause for setting specific ecotones. The results suggest that benthic communities of landlocked coastal lagoons can be highly impacted by flow reduction from freshwater aquifers under drought conditions or water abstraction activities.

Mangrove fish of São Tomé Island (Gulf of Guinea): new occurrences and habitat usage

Mangroves are recognised as important nursery and feeding areas for resident and inshore fish species. However, the importance of West African mangroves to the life cycle of fish communities remains poorly studied. The present study is the first record of fish species in tropical insular mangroves for this region and its aim was to assess habitat usage by fish species. Two mangroves of Sao Tome Island (Praia das Conchas and Malanza) were sampled with a multihabitat approach and using different fishing gear to maximise the diversity of fish species collected. Several environmental parameters were also measured. Both mangroves are nursery and opportunistic feeding grounds for fish species, as well as settlement areas for resident species. The highest number of both juveniles and adults (inshore and residents) was observed at the Malanza mangrove, which is also the largest and has the highest habitat heterogeneity. Four new occurrences were reported for the Sao Tome and Principe area, namely Pomadasys jubelini, Bostrychus africanus, Dalophis cephalopeltis and the introduced species Oreochromis mossambicus.

The suitability of EBC-Pb as a new biomarker to assess occupational exposure to lead

Occupational exposure to lead (Pb) requires continuous surveillance to assure, as much as possible, safe and healthful working conditions. This study addresses the suitability of assessing Pb exposure in relevant workers using their exhaled breath condensate (EBC). This study enrolled workers of two different Pb processing industries characterized by moderate and high Pb exposure levels in the work environment, and a group of non-exposed individuals working in offices who served as baseline for Pb exposure. The EBC-Pb of workers reflected the Pb levels in the work environment of all three settings, although the relationship with B-Pb was not clear. The lack of correlation between EBC-Pb and B-Pb most probably indicates the time lag for Pb to enter in the two body pools. The EBC-Pb seems to reflect immediate exposure, providing a prompt signature of Pb in the environmental that may interact directly with the organ. By delivering short-term evaluation of exposure, EBC-Pb represents a clear advantage in biomonitoring and may become an interesting tool for estimating organ burden.

Optical micro-tomography “OPenT” allows the study of large toadfish Halobatrachus didactylus embryos and larvae

Batrachoidids, which include midshipman and toadfish are less known among embryologists, but are common in other fields. They are characteristic for their acoustic communication, and develop hearing and sound production while young juveniles. They lay large benthic eggs (>5mm) with a thick chorion and adhesive disk and slow development, which are particularly challenging for studying embryology. Here we took advantage of a classical tissue clearing technique and the OPenT open-source platform for optical tomography imaging, to image a series of embryos and larvae from 3 to 30mm in length, which allowed detailed 3D anatomical reconstructions non-destructively. We documented some of the developmental stages (early and late in development) and the anatomy of the delicate stato-acoustic organs, swimming bladder and associated sonic muscles. Compared to other techniques accessible to developmental biology labs, OPenT provided advantages in terms of image quality, cost of operation and data throughput, allowing identification and quantitative morphometrics of organs in larvae, earlier and with higher accuracy than is possible with other imaging techniques.

Feeding ecology and life-history strategy of nesting males in a fish with long parental care, Lusitanian toadfish (Halobatrachus didactylus, Batrachoididae)

The Lusitanian toadfish, Halobatrachus didactylus , like other batrachoidids, is a benthic fish species with nesting behaviour during the breeding season. During this prolonged period it engages in mating activities and remains in the nest providing parental care. It is not known whether males feed while providing parental care but it is likely that their limited mobility may restrict their diet and influence their fitness. As a consequence, egg cannibalism could occur as a life-history strategy. The aim of the present study is to ascertain the feeding behaviour of nesting males, in comparison to mature non-nesting males, and to identify potential life-history traits related to egg cannibalism. Nest-holders were sampled from artificial nests placed in an intertidal area of the Tagus estuary, only exposed during spring low tides. The diet of nest-holders was compared with that of non-nesting mature males from the same area, captured by otter trawl. The present study demonstrates that despite their constrained mobility nest-holders feed during the breeding season, although in a more opportunistic fashion than non-nesting males. Nest-holders showed a generalist feeding behaviour, with a more heterogeneous diet. Egg cannibalism was not related to male condition, paternity or brood size but showed a higher incidence early in the season when water temperatures were lower. The results suggest a possible seasonal trade-off strategy between care and energy recovery, triggered by environmental factors, where under unfavourable conditions to sustain viable eggs the male may recover energy by eating eggs, thus benefiting future reproductive success, later in the season.