Potential human health risk from consumption of metallic elements-contaminated benthic mollusks from Don Hoi Lot sandbar, Thailand

Ecological and health implications of heavy metal bioaccumulation in Thai Fauna: A systematic review

Heavy metals pose significant threats to ecosystems and human health due to their persistence and bioaccumulation. In Thailand, rapid industrialization, extensive agriculture, and urban development have exacerbated heavy metal pollution in both aquatic and terrestrial ecosystems. This systematic review, conducted according to PRISMA guidelines, evaluates study designs and methodologies to assess heavy metal bioaccumulation in Thai fauna, with a focus on ecological and health impacts. The review reveals that fish, particularly from families like Cyprinidae and Cichlidae, account for 42.11 % of studies, with species such as swamp eel, Henicorhynchus siamensis, Arius maculatus, Osteogeneiosus militaris, Puntioplites proctozystron, and Channa striata showing significant bioaccumulation. Molluscs (31.58 %), including Tegillarca granosa and Filopaludina martensi, serve as critical bioindicators of aquatic pollution due to their filter-feeding habits. Amphibians and crustaceans, like Fejervarya limnocharis and Fenneropenaeus merguiensis, also demonstrate vulnerability to heavy metal contamination. Key contamination hotspots include urban waterways in Bangkok, industrial discharges in Songkhla Lake, and mining sites in Loei Province, highlighting widespread environmental and health impacts. Despite extensive research, gaps remain, particularly concerning benthic scavengers and detritivores, which are vital for ecosystem functions. The review underscores the need for targeted monitoring and mitigation, including stricter regulations on industrial discharges, improved waste treatment, and better management of agricultural runoff. While metals like cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn) are well-studied, further research on less-examined metals and species-specific bioaccumulation patterns is crucial to enhancing environmental management, supporting biodiversity conservation, and improving ecosystem resilience in Thailand.

Species Differences and Tissue Distribution of Heavy Metal Residues in Wild Birds

Birds are useful as bioindicators of metal pollution, but the variety of species and tissue distribution may influence the study of heavy metal burdens in birds. The objective of this study was to determine the levels of heavy metals in wild birds' carcasses to acquire information on species differences and the tissue distribution of metals in wild birds in Thailand. Species differences in metal buildup were observed in the livers and kidneys, but not in the feathers. A significantly higher accumulation of Cd was found in the livers and kidneys of the granivorous birds compared to those in the water birds. In all the groups of birds, the Pb level in the livers (>15 ppm) and feathers (>4 ppm) exceeded the threshold limits, causing potential lead poisoning and disturbing the reproductive success. The Cd accumulation in the kidneys was above 2-8 ppm, indicating increased environmental exposure to Cd in these birds. The Cd, Pb, Ni, Zn, and Fe concentrations in the livers could be estimated using the kidneys, while the Pb level in the liver may be predicted using feathers. Furthermore, water birds' feathers may be potentially appropriate bioindicators for long-term exposure. Research on the origin of metal contamination is needed to reduce the threat of heavy metals to the health of both birds and other wildlife species.

Spatial-temporal characteristics, source-specific variation and uncertainty analysis of health risks associated with heavy metals in road dust in Beijing, China

Based on the concentrations of ten heavy metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Fe) in 144 road dust samples collected from 36 sites across 4 seasons from 2016 to 2017 in Beijing, this study systematically analyzed the levels and main sources of health risks in terms of their temporal and spatial variations. A combination of receptor models (positive matrix factorization and multilinear engine-2), human health risk assessment models, and Monte Carlo simulations were used to apportion the seasonal variation of the health risks associated with these heavy metals. While non-carcinogenic risks were generally acceptable, Cr and Ni induced cautionary carcinogenic risks (CR) to children (confidence levels was approximately 80% and 95%, respectively).. Additionally, fuel combustion posed cautionary CR to children in all seasons, while the level of CR from other sources varied, depending on the seasons. Heavy metal concentrations were the most influential variables for uncertainties, followed by ingestion rate and skin adherence factor. The values and spatial patterns of health risks were influenced by the spatial pattern of risks from each source.

The impact of seasonal varied human activity on characteristics and sources of heavy metals in metropolitan road dusts

Due to significant human activity, road dust is becoming contaminated by heavy metals in many cities. To comprehensively investigate the variation of contamination level and sources of heavy metals in road dust, 10 heavy metals in road dust samples from Beijing, China, in both summer and winter, were evaluated by spatial analysis using geographic information system (GIS) mapping technology and the positive matrix factorization (PMF) Model. Although the concentrations of some heavy metals between summer and winter had similarities, the differences of others and spatial distributions of heavy metals between summer and winter were considerable. The mean concentrations of As, Cd, Cr, Cu, and Fe were lower in winter, while those of Hg, Mn, Ni, Pb, and Zn were higher. According to the values of the Pollution Index (PI) and Nemerow Integrated Pollution Index (NIPI), there were no obvious differences between summer and winter, but the range between different sites in winter was nearly twice that of summer. Based on the PMF model, four sources of heavy metals in the dust samples were identified. Although the types of sources were consistent, the relative contributions of each source differed between summer and winter. Non-exhaust vehicle emissions was the most important source in summer (34.47 wt%), while fuel combustion contributed the largest proportion to the total heavy metals in winter (32.40 wt%). The impact of each source also showed spatial variation different trends in summer and winter. With the alteration of seasons, intensity of human activities also changed, such as the number of tourists, energy needs for building temperature regulation, construction, and the amount of pesticides and fertilizer. That might be the reason for the variation of heavy metal concentrations and relative contribution of their sources between summer and winter.