Human health risk assessment of potentially toxic elements (PTEs) from environmental matrices

In assessing human health risk of potentially toxic elements (PTEs), it is not the concentration of PTEs in the environmental matrices that is of greatest concern but the fraction that is absorbed into the body via the exposure pathways. The determination of this fraction (i.e. the bioaccessible fraction) through the application of bioaccessibility protocols is the focus of this work. The study investigated human health risk of PTEs (As, Cd, Cr, Cu, Pb, Mn, Ni and Zn) from oral ingestion of soil / dust, inhalation of urban street dust and air-borne dust (PM10). To assess health risk via oral ingestion of soil and dust, total PTEs were determined in twenty nine soil samples collected from children’s playing fields and ninety urban street dusts collected from six cities. Analysis of total PTE content in these samples via ICP-MS revealed high Pb concentrations (> 450 mg/kg) in 3 playground soils and 32 urban street dusts. Detailed quantitative risk assessment (DQRA) carried out in the playgrounds showed that no significant possibility of significant harm exist in the playgrounds. The concentration of Pb from a particular dust sample based on 50 mg/day ingestion rate that a child might possibly ingest to reach the estimated tolerable daily intake was calculated and it exceeded the tolerable daily intake for oral ingestion in 4 cities. The bioaccessible PTEs were determined both in the soil and dust samples using the Unified BARGE method and the result showed that in all the samples, the PTEs solubilised more in the gastric phase than in the intestinal phase. A new method has been developed; simulated epithelial lung fluid (SELF) and was used to assess the respiratory bioaccessibility of Pb from inhalable urban dust (<10 µm). Low bioaccessibility (<10 %) was recorded in all the samples analysed

Use of simulated epithelial lung fluid in assessing the human health risk of Pb in urban street dust

In many urban contexts, non-dietary Pb exposure from street dusts may add to the overall exposure burden, and the presence of high total Pb content is well documented in urban street dust from across the globe. Given the increasing recognition of the potential adverse health effects from both the quantity and the chemical and physical composition of the inhaled fraction, and the recognition that it is the soluble fraction rather than the total element content that has more direct links to health effects, attention has focused in this study on the human health risks via this exposure pathway. In order to investigate the environmental exposure to Pb from the inhalation of urban street dusts, a newly developed in vitro simulated epithelium lung fluid (SELF) has been applied to the < 10 μm fraction of urban street dusts. In this context, 21 urban street dust samples, across five UK cities, were selected based on their high pseudo-total Pb content. The work revealed that inhalation bioaccessibility, and hence inhalation dose, varied across the cities but was generally found to be low (< 10%). Indeed, the lung bioaccessibility was far lower (% lung bioaccessibility ranged from 1.2 to 8.8) than is currently applied in two of the most commonly employed risk assessment models i.e. the Integrated Exposure Uptake Biokinetic model (IEUBK, USA) and the Contaminated Land Exposure Assessment model (CLEA, UK). The estimated inhalation dose (for adults) calculated from the PM10 bioaccessibility ranged from 7 ng kg− 1 BW day− 1 (Edinburgh) to 1.3 ng kg− 1 BW day− 1 (Liverpool). The results indicate a low potential inhalation bioaccessibility for Pb in these urban street dust samples when modelled using the neutral pH conditions of the SELF

An Estimation of Daily Intake of Potentially Toxic Elements from Urban Dust of Abakaliki, Nigeria

This study examined the total concentration of eight potentially toxic elements (PTEs) in urban dust of Abakaliki and also calculated the daily intake (DI) of these PTEs. Fifteen samples were investigated and the result revealed that the range of mean total PTE concentrations was found in this order: 3.59 – 15.3 mg/kg (As); 66.8 -172 mg/kg (Cd); 0.288 – 1.36 mg/kg (Cr); 25.4 – 86.6 mg/kg (Cu); 55.5 – 1815 mg/kg (Pb); 397 – 1389 mg/kg (Mn); 22.3 – 52.7 mg/kg (Ni) and 73.3 – 434 mg/kg (Zn). For each element the highest concentration (representing the worst-case scenario was used to calculate the daily intake and it was observed that only Pb with a DI of 4.88 μg kgbw -1 day-1 exceeded Pb recommended tolerable daily intake (TDI) of 3.6 μg kgbw-1 day-1. Based on a soil and dust ingestion rate of 50 mg /day for children between the age of 1 and &lt;6 year, the amount of dust that a child would ingest in order to exceed the recommended tolerable daily intake TDI was also calculated.Keywords: urban dust, potentially toxic elements (PTEs), oral ingestion, Abakaliki, tolerable daily intake (TDI

Determination of trace elements in urban airborne particulates (PM10) using energy dispersive X-ray fluorescence (EDXRF) spectroscopy

assessment of the air quality in Newcastle upon Tyne, UK was performed by determining the trace element content in airborne particulates (PM10). Samples were collected over a 12 month period (March 2011 to April 2012) using two high volume air sampler provided with a PM10 size selective inlet. The concentrations of 6 elements (Cr, Cu, Mn, Ni, Pb and Zn) were determined. The mean concentrations of these elements varied widely across the elements with Zn showing the highest concentration (41.3 \ub1 42.8 ng/m3; ranging from 9.9 \u2013 209.0 ng/m3) and Cr the least concentration (1.7 \ub1 0.9 ng/m3; ranging from 0.4 \u2013 3.2 ng/m3). The total elemental content obtained in this work was compared with regulatory limit values for 4 of the elements determined and it was discovered that none exceeded the limit values

Oral bioaccessibility of potentially toxic elements (PTEs) in urban dusts of Abakaliki, Ebonyi State, Nigeria

A literature survey has shown that no study has investigated the oral bioaccessibility of PTEs in Nigeria dusts. Studies on human health risk of PTEs from urban Nigeria dust have been based only on total elemental concentrations. Whilst this protocol is useful in assessing human health of PTEs, it could lead to an over estimation of the risk considering the elemental sequestration in the dust samples. This study deviated from previous studies by examining the total concentrations as well as the oral bioaccessibility of 8 PTEs in 15 urban dust samples collected from Abakaliki, Ebonyi State, Nigeria. The result showed that high concentrations of Pb (ranging from 236 \u2013 1815 mg/kg) were observed in 5 locations. The Unified Bioaccessibility Method (UBM) was used to investigate the oral bioaccessibility of these PTEs in the urban dust samples. The result revealed that all the PTEs were more bioaccessible in the gastric phase that the gastric + intestinal phase. The lead tolerable daily intake (TDI), as well as the bioaccessible TDI, was computed and results compared with a guideline value

Injurious Suicide Attempts Among Middle and High Schhol Students

Injurious Suicide Attempts Among Middle and High School Students: Association with Sexual Dating Violence and Substance Use Christian Nwabueze, Hilary Elom Introduction: Suicide is one of the leading causes of death among the teenage population. Substance use and sexual dating violence is also common among this group. Aim: To determine the association between sexual dating violence, substance use and the risk of injurious suicide attempts. Methods: The data consists of a nationally representative sample of 15, 624 Middle and High School students in the 2015, Youth Behavioral Risk Surveillance System Survey. Majority of the respondents were aged 13 to 17 years. Results: There were 7757 (50.03%) females and 7749 (49.97%) males. There were 8666 (66.3%) and Blacks and Asians were 14.87% and 5.63% respectively. A total of 1072 (9.87%) had attempted injurious suicide in the past year (females=68.1%, males =31.91%). About 10% had experienced sexual violence within the last year. The proportion attempted suicides who were illegal drugs users, current alcohol, tobacco and marijuana users were 9.14%, 8.87%, 9.08%, 9.36% respectively. Those who did not experience sexual dating violence had a higher odd (OR=1.81, CI = 1.497 – 2.188, P = \u3c0.0001) of injurious suicide than those who did not date at all. Abstinence from smoking, alcohol, marijuana and illegal drug use (OR = 0.396, CI = 0.341 – 0.459, p = \u3c0.0001) in the past month was significantly associated with reduced risk for injurious suicide attempts. Conclusion: Abstinence from substance use reduces the risk for injurious suicide attempts among middle and high school students. Sexual dating violence seems to be a significant risk factor for injurious suicide attempts in this group. Key words: suicide, sexual violence, substance use, abstinenc

How safe is the playground? An environmental health risk assessment of As and Pb levels in school playing fields in NE England

The risk from potentially toxic elements in playground soils is of concern to children’s health as a result of the potential for intentional or unintentional consumption. Current approaches, based on total potentially toxic element concentration, may overestimate the risk. This has resulted in the development and use of in vitro gastrointestinal extraction protocols. The concentration of arsenic (As) and lead (Pb) in soils collected from 12 schools in north-east England has been compared with Soil Guideline Values from seven countries as well as reported literature concentrations for playgrounds and recreational parks. It was found that the mean As concentration of 14.1 ± 5.4 mg/kg does not exceed the England residential Soil Guideline Value in any location, while the mean Pb concentration of 298 ± 380 mg/kg is high but not excessive. Both concentrations have been assessed using the maximum potential daily intake from soil that a child could ingest. Based on this protocol Pb does not exceed the tolerable daily intake in any playground location, while As is generally 10 times lower than the oral index dose in the majority of playgrounds. The oral bioaccessibility of As and Pb was investigated. It was concluded that the highest concentrations were determined in the gastric phase with maximum bioaccessibilities of 54 and 46 % for As and Pb, respectively. Here we have demonstrated that minimal risk arises from the investigated playgrounds provided that good personal hygiene is adhered to

Human health risk from Pb in urban street dust in northern UK cities

The presence of Pb in the environment can cause significant health problems. These issues are exasperated when the lead is in a more amenable form for potential ingestion. This study investigates the potential human health risk from Pb in urban street dusts. The lead levels in urban street dust in major city centres in northern UK have been compared to levels determined in 35 cities around the world. With a few exceptions, it was noted that the mean Pb levels in this study exceeded those found in other cities worldwide. Samples (n = 15) of urban street dust were collected across five city centres, and specifically in areas in which pedestrians are likely to concentrate, as well as near historical buildings. Typical total lead concentrations across all sampling sites ranged from 306 to 558 mg/kg. The human health risk was assessed using oral bioaccessibility testing of the urban street dust. The mean oral bioaccessibility data, irrespective of site and sample location, were in the range 43 ± 9 %. The total and bioaccessible concentrations of lead were compared to the estimated tolerable daily intake (TDIoral) values based on unintentional soil/dust consumption. It is noted, in all cases, that the maximum estimated lead daily intake exceeded the TDIoral. An alternative approach for assessing the daily intake is proposed based on the actual measured air quality in selected cities on the same day as the sampled urban dust

Oral bioaccessibility of potentially toxic elements (PTEs) in urban dusts of Abakaliki, Ebonyi State, Nigeria

A literature survey has shown that no study has investigated the oral bioaccessibility of PTEs in Nigeria dusts. Studies on human health risk of PTEs from urban Nigeria dust have been based only on total elemental concentrations. Whilst this protocol is useful in assessing human health of PTEs, it could lead to an over estimation of the risk considering the elemental sequestration in the dust samples. This study deviated from previous studies by examining the total concentrations as well as the oral bioaccessibility of 8 PTEs in 15 urban dust samples collected from Abakaliki, Ebonyi State, Nigeria. The result showed that high concentrations of Pb (ranging from 236 – 1815 mg/kg) were observed in 5 locations. The Unified Bioaccessibility Method (UBM) was used to investigate the oral bioaccessibility of these PTEs in the urban dust samples. The result revealed that all the PTEs were more bioaccessible in the gastric phase that the gastric + intestinal phase. The lead tolerable daily intake (TDI), as well as the bioaccessible TDI, was computed and results compared with a guideline value.Keywords: Urban dust; PTEs; oral ingestion; bioaccessibility; ICP-MS; Abakalik