The importance of evaluating metal exposure and predicting human health risks in urban-periurban environments influenced by emerging industry

Health risk assessment of cadmium pollution emergency for urban populations in Foshan City, China

With rapid socioeconomic development, water pollution emergency has become increasingly common and could potentially harm the environment and human health, especially heavy metal pollution. In this paper, we investigate the Cd pollution emergency that occurred in the Pearl River network, China, in 2005, and we build a migration and transformation model for heavy metals to simulate the spatiotemporal distribution of Cd concentrations under various scenarios of Cd pollution emergency in Foshan City. Moreover, human health hazard and carcinogenic risk for local residents of Foshan City were evaluated. The primary conclusions were as follows: (1) the number of carcinogen-affected people per year under scenario 1 reached 254.41 when the frequency was 0.1 year/time; specifically, the number of people with cancer per year in the area of the Datang, Lubao, and Nanbian waterworks was 189.36 accounting for 74% of the total number per year; (2) at the frequency of 5 years/time, the Lubao waterwork is the only one in extremely high- or high-risk grade, while besides it, the risk grade in the Datang, Nanbian, Xinan, Shitang, and Jianlibao waterworks is in the extremely high or high grade when the frequency is 0.1 year/time; (3) when Cd pollution accidents with the same level occurs again, Cd concentration decreases to a low level in the water only if the migration distance of Cd is at least 40-50 km. Based on the health risk assessment of Cd pollution, this study gives the recommendation that the distance should keep above 50 km in tidal river network of the Pearl River Delta between those factories existing the possibility of heavy metal pollution and the drinking water source. Only then can the public protect themselves from hazardous effects of higher levels of heavy metal.

Ear-like poly (acrylic acid)-activated carbon nanocomposite: A highly efficient adsorbent for removal of Cd(II) from aqueous solutions

Poly (acrylic acid) modified activated carbon nanocomposite (PAA-AC) was synthesized. The structure and morphology of this nanocomposite were characterized by FTIR, SEM, TEM, XRD and Zeta potential. The adsorption of some heavy metal ions on PAA-AC was studied. The characterization results indicated that PAA-AC was a novel and ear-like nanosheet material with the thickness of about 40 nm and the diameter of about 300 nm. The adsorption results exhibited that the introduction of carboxyl groups into activated carbon evidently increased the uptake for heavy metal ions and the nanocomposite had maximum uptake for Cd(II). Various variables affecting adsorption of PAA-AC for Cd(II) were systematically explored. The maximum capacity and equilibrium time for adsorption of Cd(II) by PAA-AC were 473.2 mg g^-1 and 15 min. Moreover, the removal of Cd(II) for real electroplating wastewater by PAA-AC could reach 98.5%. These meant that the removal of Cd(II) by PAA-AC was highly efficient and fast. The sorption kinetics and isotherm fitted well with the pseudo-second-order model and Langmuir model, respectively. The adsorption mainly was a chemical process by chelation. Thermodynamic studies revealed that the adsorption was a spontaneous and endothermic process. The results revealed that PAA-AC could be considered as a potential candidate for Cd(II) removal.

Lead and cadmium contamination and exposure risk assessment via consumption of vegetables grown in agricultural soils of five-selected regions of Pakistan

Rapid urbanization and industrialization result in serious contamination of soil with toxic metals such as lead (Pb) and cadmium (Cd), which can lead to deleterious health impacts in the exposed population. This study aimed to investigate Pb and Cd contamination in agricultural soils and vegetables in five different agricultural sites in Pakistan. The metal transfer from soil-to-plant, average daily intake of metals, and health risk index (HRI) were also characterized. The Pb concentrations for all soils were below the maximum allowable limits (MAL 350 mg kg-1) set by State Environmental Protection Administration of China (SEPA), for soils in China, while Cd concentrations in the soils were exceeded the MAL (61.7-73.7% and 4.39-34.3%) set by SEPA (0.6 mg kg-), and European Union, (1.5 mg kg-1) respectively. The mean Pb concentration in edible parts of vegetables ranged from 1.8 to 11 mg kg-1. The Pb concentrations for leafy vegetables were higher than the fruiting and pulpy vegetables. The Pb concentrations exceeded the MAL (0.3 mg kg-1) for leafy vegetables and the 0.1 mg kg-1 MAL for fruity and rooty/tuber vegetables set by FAO/WHO-CODEX. Likewise, all vegetables except Pisum sativum (0.12 mg kg-1) contained Cd concentrations that exceeded the MAL set by SEPA. The HRI values for Pb and Cd were <1 for both adults and children for most of the vegetable species except Luffa acutangula, Solanum lycopersicum, Benincasa hispada, Momordi charantia, Aesculantus malvaceae, Cucumis sativus, Praecitrullus fistulosus, Brassica oleracea, and Colocasia esculanta for children. Based on these results, consumption of these Pb and Cd contaminated vegetables poses a potential health risk to the local consumers.

Bioavailability evaluation, uptake of heavy metals and potential health risks via dietary exposure in urban-industrial areas

A verity of human activities i.e. urbanization and industrialization have been resulted serious environmental contaminations by heavy metals in all over the world. The settlement of populations in urban and nearby industrial areas for economic development has significant share in their exposure to these metallic contaminants. Depending on the nature and type of the pollutants, targeted urban-industrial environments can have harmful and chronic health risk impacts on exposed local inhabitants and may require detoxification, healing and remedial therapy. Consequently, environmental monitoring as well as human health risk assessments of urban environments under industrial influence are key dominant features. We believe this work will provide new insights into the studies of metals exposure and associated health risks in emerging industrials cities of developing countries. Present study aimed to study the bioavailability of metals, quantify the changeability in soil and vegetable metal concentrations and estimation of human health risks via dietary exposure, focusing on urban-industrial environment. Soil and vegetable samples were collected in six random sites within the urban, periurban and industrial areas and analyzed for metal concentrations. In addition, risk assessment model proposed by US-EPA was employed to estimate the potential health risk of heavy metals via dietary intake. Results indicated that the heavy metal concentrations were noteworthy in periurban and urban-industrial areas. However, contamination levels varied with the type of vegetable, and the point source pollution such as traffic, urban wastes and industrial effluent. According to the estimated THQ and HI values for non-carcinogenic risk, little or no negative impact of heavy metals was observed on local inhabitants. However, the concentrations of Cr, Cd, Pb and Ni were nearly closed to the permissible limits described by US-EPA in urban-industrial areas. Conclusively, some efficient remedial strategies should be focus to overcome the increasing levels of Cr, Cd, Pb and Ni in this study area to protect the health of local inhabitants.

Spatial gradient of human health risk from exposure to trace elements and radioactive pollutants in soils at the Puchuncaví-Ventanas industrial complex, Chile

The Punchuncaví Valley in central Chile, heavily affected by a range of anthropogenic emissions from a localized industrial complex, has been studied as a model environment for evaluating the spatial gradient of human health risk, which are mainly caused by trace elemental pollutants in soil. Soil elemental profiles in 121 samples from five selected locations representing different degrees of impact from the industrial source were used for human risk estimation. Distance to source dependent cumulative non-carcinogenic hazard indexes above 1 for children (max 4.4 - min 1.5) were found in the study area, ingestion being the most relevant risk pathway. The significance of health risk differences within the study area was confirmed by statistical analysis (ANOVA and HCA) of individual hazard index values at the five sampling locations. As was the dominant factor causing unacceptable carcinogenic risk levels for children (<10^-4) at the two sampling locations which are closer to the industrial complex, whereas the risk was just in the tolerable range (10^-6 - 10^-4) for children and adults in the rest of the sampling locations at the study area. Furthermore, we assessed gamma ray radiation external hazard indexes and annual effective dose rate from the natural radioactivity elements (²²⁶Ra, ²³²Th and ⁴⁰K) levels in the surface soils of the study area. The highest average values for the specific activity of ²³²Th (31 Bq kg^-1), ⁴⁰K (615 Bq kg^{- 1}), and ²²⁶Ra (25 Bq kg^-1) are lower than limit recommended by OECD, so no significant radioactive risk was detected within the study area. In addition, no significant variability of radioactive risk was observed among sampling locations.