Arsenic Levels and Speciation from Ingestion Exposures to Biomarkers in Shanxi, China: Implications for Human Health

Abstract

Chronic exposure to arsenic (As) threatens human health. To systematically understand the health risks induced by As ingestion, we explored water and diet contributions to As exposure, and compared As in biomarkers and the arsenicosis in a geogenic As area in China. In this study, high percentages of water (77% of n = 131 total samples), vegetables (92%, n = 120), cereals (32%, n = 25), urine (70%, n = 99), nails (76%, n = 176), and hair (62%, n = 61) contained As higher than the acceptable levels. Dietary As contributed 92% of the average daily dose (ADD) when the water As concentration was less than 10 μg/L, for which 5 out of 30 examined participants were diagnosed with arsenicosis symptoms. The distinct positive correlation between ADD and As concentrations in urine, nails, and hair suggests different applicability for these biomarkers. Methylated As as the predominant urinary As species confirms that the ingested inorganic As is methylated and is excreted through urine. In situ microdistribution and speciation analysis indicates that As is mainly associated with sulfur in nails and hair. Nails, rather than hair and urine, could be used as a proper biomarker for arsenicosis. High ADD from the environment and low excretion could result in As toxicity to humans. ■ INTRODUCTIONArsenic (As) poses a severe threat to human health through exposure pathways mainly including water and diet. 1,2 Drinking water with elevated As levels is the primary source of As ingestion. 1,3 Moreover, As-laden groundwater, if used for irrigation, can lead to appreciable amounts of As accumulation in vegetables and cereals. 4−6 Extensive research demonstrates that rice and rice products could be another As source. 7,8 However, not much attention has been paid to other cereals like wheat, which are important staple foods worldwide, that could lead to significant As ingestion. 9 The intake of As results in its detection in noninvasive human biomarkers such as urine, nails, and hair. 10−12 Urine has frequently been used as a biomarker for short-term exposure because most As metabolites are excreted within 3−4 days through urine. 12,13 Nails and hair indicate long-term exposure for 2−12 months, 10 as As can be accumulated in these structures rich in keratin. 14 Thus, the association of As levels in biomarkers and groundwater has been recently studied to evaluate its health risks. 11,15 The speciation of As in biomarkers is crucial to understand the transformation, metabolism, and toxicity of ingested As. 12,16 As species in hair and nails are traditionally determined by chemical extraction, where inorganic and methylated As are detected. 14,17 No As−S species have been reported using indirect chemical extraction methods, even though As readily bonds to sulphydryl groups. 14 In contrast, As−S species have been detected in nail and hair samples using in situ X-ray absorption near-edge structure (XANES) spectroscopy. 15 Unfortunately, methylated As species are not distinguished from the As−S form in nails, 18 which deserves further...

Removal of arsenate with hydrous ferric oxide coprecipitation: Effect of humic acid

“…Then, the ternary suspension was mixed for 24 hr at pH 7.0 ± 0.1, and filtered through a 0.4 μm membrane. The soluble As concentration in the filtrate was determined with an atomic fluorescence spectrometer (AFS, Ruiguang, China) with a detection limit of 0.6 μg/L (Cui et al, 2013). Triplicate adsorption experiments were performed and averaged values were reported.…”

Proteomic profiling reveals candidate markers for arsenic-induced skin keratosis

“…Arsenic-induced skin lesions are endemic in many remote mountainous regions in China, especially in the Shanyin district (Guo et al, 2003). Average arsenic concentrations in groundwater there are nearly 17 times higher than the United States Environmental Protection Agency guideline of 10 mg/ L, and typical clinical features of hyperkeratosis of palms and soles are observed (Cui et al, 2013). Previous work has found that individuals in this region had higher arsenic content in hair and nail than the average Chinese, consistent with arsenic induction of dermatological lesions (Cui et al, 2013).…”

“…Average arsenic concentrations in groundwater there are nearly 17 times higher than the United States Environmental Protection Agency guideline of 10 mg/ L, and typical clinical features of hyperkeratosis of palms and soles are observed (Cui et al, 2013). Previous work has found that individuals in this region had higher arsenic content in hair and nail than the average Chinese, consistent with arsenic induction of dermatological lesions (Cui et al, 2013). Those people with noncancerous skin lesions are at high risk of developing skin and internal cancers (Mead, 2005).…”

Groundwater arsenic removal by coagulation using ferric(III) sulfate and polyferric sulfate: A comparative and mechanistic study

“…The As speciation was determined using high-performance liquid chromatography (HPLC) coupled with a hydride generation atomic fluorescence spectrometer (HG-AFS-8130, Jitian, Beijing, China) installed in a local farmer's house (Cui et al, 2013). Briefly, online separation of As species was carried out with a Hamilton PRP-X100 anion exchange column, using 15 mmol/L phosphate buffer at pH 6 as mobile phase at 1.0 mL/min flow rate.…”

“…FS (industrial grade, 21% as Fe) and PFS (industrial grade, 22% as Fe) were obtained from Bodi Chemical Co. Ltd. Tianjin, China. Ten groundwater samples (G1-G10 in Table 1) were randomly collected from Shanxi, China, where As contamination in groundwater prevails (Cui et al, 2013;Luo et al, 2012), and were used to evaluate water chemistry influences on As removal. Because the average As concentration in local groundwater was about 300 μg/L as reported in our previous study (Luo et al, 2012), three samples containing comparable or higher As levels including 321 μg/L (G5), 578 μg/L (G8), and 1067 μg/L (G10) were selected for further study.…”