Cumulative arsenic exposure is associated with fungal infections: Two cohort studies based on southwestern and northeastern basins in Taiwan

Assessing the health risks of coal-burning arsenic-induced skin damage: A 22-year follow-up study in Guizhou, China

Risk assessment of arsenic-induced skin damage has always received significant global attention. Theories derived from arsenic exposure in drinking water may not be applicable to the coal-burning type to arsenic-exposed area. Furthermore, very few studies have successfully determined the reference value of cumulative arsenic (CA) exposure that leads to specific skin lesions. In this study, we conducted a 22-year follow-up investigation to assess the risk of skin lesions and cancer resulting from long-term, multi-channel arsenic exposure from hazard identification, dose-response assessment, exposure assessment, and risk characterization. The results show that the arsenic exposure can significantly increase the prevalence of skin lesions. For each interquartile range increase of hair arsenic (HA) and CA, the risk of skin damage increased by 1.91 and 3.90 times, respectively. The lower confidence limit of the benchmark dose of HA of arsenic-induced various skin lesions ranged from 0.07 to 0.12 μg·g-1, and 932.57 to 1368.92 mg for CA. The chronic daily intake, lifetime average daily dose in the arsenic-exposed area after the comprehensive prevention and control measures have decreased significantly, but remained higher than the daily baseline level of 3.0 μg·kg-1·d-1. Even as recently as 2020, the hazard quotients and hazard index still exceeded 1, measuring 155.33 and 55.20, and the lifetime excess risk of skin cancer (2.80 × 10-3) remains significantly higher than the acceptable level of 10-6. Our study underscores the effectiveness of comprehensive prevention and control measures in managing high arsenic exposure in coal-burning arsenic poisoning areas. However, it is crucial to acknowledge that the risk of both non-carcinogenic and carcinogenic effects on the skin remains substantially higher than the acceptable level. We recommend setting reference limits for monitoring skin damage among individuals exposed to arsenic, with a recommended upper limit of 0.07 μg·g-1 for HA and a maximum acceptable level of 935.57 mg for CA.

TIMP3 Gene Polymorphisms of -1296 T > C and -915 A > G Increase the Susceptibility to Arsenic-Induced Skin Cancer: A Cohort Study and In Silico Analysis of Mutation Impacts

Long-term exposure to arsenic may induce several human cancers, including non-melanoma skin cancer. The tissue inhibitor of metalloproteinase (TIMP)-3, encoded by the TIMP3 gene, may inhibit tumor growth, invasion, and metastasis of several cancer types. In this study, we aimed to investigate effects of the TIMP3 -1296 T > C (rs9619311) and -915 A > G (rs2234921) single-nucleotide polymorphisms (SNPs) on skin cancer risk in an arsenic-exposed population, and to evaluate the influence of allele-specific changes by an in silico analysis. In total, 1078 study participants were followed up for a median of 15 years for newly diagnosed skin cancer. New cases were identified through linkage to the National Cancer Registry of Taiwan. A Cox regression analysis was used to evaluate the effects of TIMP3 variants. Transcription factor (TF) profiling of binding sites of allele-specific changes in SNPs was conducted using the JASPAR scan tool. We observed borderline associations between TIMP3 genotypes and skin cancer risk. However, when combined with high arsenic exposure levels, the rs9619311 C allele, rs2234921 G allele, or C-G haplotype groups exhibited a greater risk of developing skin cancer compared to the respective common homozygous genotype group. The in silico analysis revealed several TF motifs located at or flanking the two SNP sites. We validated that the C allele of rs9619311 attenuated the binding affinity of BACH2, MEIS2, NFE2L2, and PBX2 to the TIMP3 promoter, and that the G allele of rs2234921 reduced the affinity of E2F8 and RUNX1 to bind to the promoter. Our findings suggest significant modifications of the effect of the association between arsenic exposure and skin cancer risk by the TIMP3 rs9619311 and rs2234921 variants. The predicted TFs and their differential binding affinities to the TIMP3 promoter provide insights into how TIMP3 interacts with arsenic through TFs in skin cancer formation.

Estimation of potential arsenic leaching from its phases in excavated sedimentary and metamorphic rocks

It is important that hazardous excavated sedimentary and metamorphic rocks are treated appropriately and reused without posing an environmental risk. Up-flow column leaching tests were conducted to examine whether arsenic leaching behavior varied among five hazardous excavated sedimentary and metamorphic rocks (two mudstones, clay sediment of marine origin, slate, and black schist) and to determine whether the potential amount of arsenic leaching could be estimated based on the arsenic-bearing mineral phases in the rock. Changes in arsenic concentration with pore volume (PV) showed the same pattern across all rock types, except for one that contained an extremely low amount of water-soluble arsenic, exhibiting an initial increase to reach a peak, followed by a decrease. The arsenic amounts leached before and after the PV at which the arsenic concentration peaked, corresponded to 88% ± 20% of the amount of arsenic fraction 1 obtained by sequential extraction and 76% ± 10% of the amount of arsenic fraction 2, respectively, while the potential amount of arsenic leaching corresponded to 65-89% of the summed total of arsenic fractions 1 + 2. These findings indicate that arsenic exhibits the same leaching behavior among different types of hazardous excavated sedimentary and metamorphic rocks except where extremely low amounts of water-soluble arsenic are present and that the potential amount of arsenic leaching can be approximated by calculating the summed total of arsenic fractions 1 + 2, which allows us to estimate the minimum amount of material required for treatments such as immobilization conducted to prevent arsenic leaching.

Arsenic-Induced Carcinogenesis and Immune Dysregulation

Arsenic, a metal ubiquitously distributed in the environment, remains an important global health threat. Drinking arsenic-contaminated water is the major route of human exposure. Exposure to arsenic contributes to several malignancies, in the integumentary, respiratory, hepatobiliary, and urinary systems. Cutaneous lesions are important manifestations after long-term arsenic exposure. Arsenical skin cancers usually herald the development of other internal cancers, making the arsenic-induced skin carcinogenesis a good model to investigate the progression of chemical carcinogenesis. In fact, only a portion of arsenic-exposed humans eventually develop malignancies, likely attributed to the arsenic-impaired immunity in susceptible individuals. Currently, the exact pathophysiology of arsenic-induced carcinogenesis remains elusive, although increased reactive oxidative species, aberrant immune regulations, and chromosome abnormalities with uncontrolled cell growth might be involved. This review discusses how arsenic induces carcinogenesis, and how the dysregulated innate and adaptive immunities in systemic circulation and in the target organs contribute to arsenic carcinogenesis. These findings offer evidence for illustrating the mechanism of arsenic-related immune dysregulation in the progression of carcinogenesis, and this may help explain the nature of multiple and recurrent clinical lesions in arsenic-induced skin cancers.

Exploring the arsenic removal potential of various biosorbents from water

Globally, contamination of groundwater with toxic arsenic (As) is an environmental and public health issue given to its carcinogenic properties, thereby threatening millions of people relying on drinking As-contaminated well water. Here, we explored the efficiency of various biosorbents (egg shell, java plum seed, water chestnut shell, corn cob, tea waste and pomegranate peel) for arsenate (As(V)) and arsenite (As(III)) removal from As-contaminated water. Significantly, egg shell and java plum seed displayed the greatest As(III) elimination (78-87%) at 7 pH followed by water chestnut shell (75%), corn cob (67%), tea waste (74%) and pomegranate peel (65%). In contrast, 71% and 67% of As(V) was removed at pH 4.1 and 5.3 by egg shell and java plum seed, respectively. The maximum As(V) and As(III) sorption by all the biosorbents was obtained, notably for egg shell and java plum seed, after 2 h contact time. Langmuir isotherm and pseudo-second order models best fitted the sorption data for both forms of As. The -OH, -COOH, -NH₂ and sulfur-bearing surface functional groups were possibly involved for As(III) and As(V) removal by biosorbents. The scanning electron microscopy combined with the energy dispersive X-ray spectroscopy (SEM-EDX) analysis showed that the heterogeneous surface of biosorbents, possessing rough and irregular areas, could have led to As sorption. Both As(V) and As(III) were successfully desorbed (up to 97%) from the biosorbents in four sorption/desorption (regeneration) cycles. This pilot-scale study highlights that egg shell and java plum seed have the greatest ability to remove both As species from As-contaminated drinking water. Importantly, these findings provide insights to develop an inexpensive, effective and sustainable filtration technology for the treatment of As in drinking water, particularly in developing countries like Pakistan.

Human health implications, risk assessment and remediation of As-contaminated water: A critical review

Arsenic (As) is a naturally occurring metalloid and Class-A human carcinogen. Exposure to As via direct intake of As-contaminated water or ingestion of As-contaminated edible crops is considered a life threatening problem around the globe. Arsenic-laced drinking water has affected the lives of over 200 million people in 105 countries worldwide. Limited data are available on various health risk assessment models/frameworks used to predict carcinogenic and non-carcinogenic health effects caused by As-contaminated water. Therefore, this discussion highlights the need for future research focusing on human health risk assessment of individual As species (both organic and inorganic) present in As-contaminated water. Various conventional and latest technologies for remediation of As-contaminated water are also reviewed along with a discussion of the fate of As-loaded waste and sludge.