Sequential Extractions and Toxicity Potential of Trace Metals Absorbed into Airborne Particles in an Urban Atmosphere of Southwestern Nigeria

The paper investigates the hypothesis that biotoxicities of trace metals depend not only on the concentration as expressed by the total amount, but also on their geochemical fractions and bioavailability. Airborne particles were collected using SKC Air Check XR 5000 high volume Sampler at a human breathing height of 1.5–2.0 meters, during the dry season months from November 2014 to March 2015 at different locations in Akure (7°10′N and 5°15′E). The geochemical-based sequential extractions were performed on the particles using a series of increasingly stringent solutions selected to extract metals (Cd, Cu, Cr, Ni, Pb, Zn, and Mn) into four operational geochemical phases—exchangeable, reducible, organic, and residual—and then quantified using an Atomic Absorption Spectrophotometer. The results showed metals concentration of order Pb > Cr > Cd > Zn > Ni > Cu > Mn. However, most metals in the samples exist in nonmobile fractions: exchangeable (6.43–16.2%), reducible (32.58–47.39%), organic (4.73–9.88%), and residual (18.28–27.53%). The pollution indices show ingestion as the leading route of metal exposure, with noncarcinogenic (HQ) and cancer risk (HI) for humans in the area being higher than 1.0 × 10−4, indicating a health threat

Trace Elements in Urban Particulate Matters: Variations in Serum Levels, Inhalation Bioaccessibility, Health and Disease Effects

Trace elements-bound to particulate matters are often become entrained in human respiratory airway, deposited in human nasal cavity and made available for absorption by human tracheobronchial. It has been assumed that variability and bioaccessibility of elements in the serum correlate with some health and diseases. This chapter is a summary of previous works on bioaccessibility of trace elements bound to inhale particulates using different kinds of simulated body fluids. Presented also are evidences of serum variation in some respiratory diseases, such as chronic obstructive pulmonary disease (with or without hypertension), emphysema, bronchiectasis and bronchial asthma, non-tuberculose mycobacterial (NTM) lung disease, idiopathic pulmonary fibrosis (IPF)

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Atmospheric Volatile Organic Compounds and Ozone Creation Potential in an Urban Center of Southern Nigeria

The relative contribution of individual volatile organic compounds (VOC) species to photochemical ozone formation depends on their atmospheric concentrations and their oxidation mechanism. In an attempt to evaluate the ozone creation potential of ambient VOCs captured in an urban settlement of Benin City, Nigeria, the VOCs concentrations data collected in field studies at nine measurement sites of different air quality in the city and a background site were analysed. Air samples were collected at human breathing height of 1.5 meters from ground level at each site. Active sampling method using the low volume sampling pump (Acuro, Drager, Lubeck, Germany) was used to drawn the air into the tube; the absorbent was Chromosorb 106. The sampling periods were between May 2010 and June 2011; the period covered both dry and wet seasons. The adsorbed gases were desorbed using solvent extraction method with carbon disulphide as solvent. The extracted solutions were analyzed with gas chromatography and mass spectrometer. The observed concentrations of individual VOCs were determined and maximum incremental reactivity (MIR) coefficient along with rate constants of VOC-OH reactions were applied to assess the ozone formation potential of individual VOC in the ambient atmosphere. Sixteen VOC species were observed at various sites with mixing height in decreasing order: toluene (5.82), mp-xylene (3.58), ethylbenzene (3.46), benzene (2.29), and n-butane (0.84). The ozone formation potential study revealed that, ranking by propyl-equivalent, the alkanes included in this study account for 58% of the total propyl-equivalent concentration. The total ozone creation potential in the atmosphere of the Benin City was calculated to be 281.1 µg/m3. A comparison of total ozone formation potential (OFP) in our study with results obtained from other cities of the world revealed that the total concentration of ozone production in our study is threefold lower than the values reported in China city of Foshan. It is suggested that the sources of this pollutant need to be monitored in the area as a way of curtailing the impact of ozone in this city

Data set on concentrations, bioavailability, dose and lung deposition of labile metals bound to inhalable and respirable fractions of ambient particulate matters in Akure suburbs

This article consists of data sets of concentrations, dose and deposition of some labile metals bound to inhale ambient particulate matter collected at human breathing height of 1.5–2 m in Akure, South Western Nigeria. Ten (10) data points, of different air quality, were selected for study using active sampling method; during the dry season months of November, 2016 to March, 2017. At each data point, the dust particles were collected four times, sorted into inhalable and respirable fractions. The metal concentrations in each fraction were determined using Perkin-Elmer 6000 Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES) analysis. The data set were processed and analyzed via descriptive statistics (averages and standard deviations), and numerical analyses. The data were explored further to estimate the exposure dose of metal particles and deposition in various regions of lung (alveolar, trachea-bronchial and extra thoracic) in adults (male and female) dwelling in the area. The data revealed that the highest dose and deposition of metals (Pb, Cd and Cr) occur in the alveolar region of the lung of adults. Keywords: Ambient particulate matter, Inhalable and respirable, Metals, Health risk, Exposure dos