Arsenic: bioaccessibility from seaweed and rice, dietary exposure calculations and risk assessment

Abstract

Arsenic is a metalloid that occurs in food and the environment in different chemical forms. Inorganic arsenic is classified as a class I carcinogen. The inorganic arsenic intake from food and drinking water varies depending on the geographic arsenic background. Non-dietary exposure to arsenic is likely to be of minor importance for the general population within the European Union. In Europe, arsenic in drinking water is on average low, but food products (e.g. rice and seaweed) are imported from all over the world including from regions with naturally high arsenic levels. Therefore, specific populations living in Europe could also have a high exposure to inorganic arsenic due to their consumption pattern. Current risk assessment is based on exposure via drinking water. For a good estimation of the risks of arsenic in food, it is important to investigate if the bioavailability of inorganic arsenic from food is different from drinking water. The present study further explores the issue of European dietary exposure to inorganic arsenic via rice and seaweed and its associated health risks. The bioavailability of inorganic arsenic was measured in in vitro digestion experiments. The data indicate that the bioavailability of inorganic arsenic is similar for rice and seaweed compared with drinking water. The calculated dietary intake for specific European Union populations varied between 0.44 and 4.51 µg kg⁻¹ bw day⁻¹. The margins of exposure between the inorganic intake levels and the BMDL0.5 values as derived by JECFA are low. Decreasing the intake of inorganic arsenic via Hijiki seaweed could be achieved by setting legal limits similar to those set for rice by the Codex Alimentarius Commission in July 2014.

Concentrations and speciation of arsenic in New England seaweed species harvested for food and agriculture

“…While relatively low levels of As bioaccessibility have been reported (11–29 %; (Sartal et al, 2012), several studies have found the majority of both iAs and total As, which is predominantly arsenosugars, in seaweed are solubilized by simulated digestion (Laparra et al, 2003; Almela et al, 2005; Koch et al, 2007; Brandon et al, 2014). Using a caco-2 cells as a model for the intestinal barrier, iAs has been found to have much higher permeability (62%) across the intestinal wall than arsenosugars (1.7–2.8%) (Leffers et al, 2013a), although following consumption of a pure arsenosugar compound by human subjects, up to 98% was recovered in urine (Raml et al, 2009).…”

“…The bioavailability of arsenosugars to bladders cells is also low relative to iAs, however uptake of thio-DMA V , a cytotoxic metabolite of arsenosugars, is higher than As III in these cells (Leffers et al, 2013a). The high bioaccessibility of iAs from seaweed, suggests it should be considered completely bioavailable when assessing exposure, similar to drinking water (Brandon et al, 2014). While the metabolism, distribution in the body, and toxicological behavior of organic As compounds require further study, arsenosugars have been shown to be metabolized, and are therefore also considered bioavailable to humans.…”

“…per day. Seaweed consumption in Japanese populations have been estimated at 4–7 g per day (Zava and Zava, 2011), but is not well documented in the USA or Europe, and is presumed to be much lower, with the exception of specific subpopulations (Brandon et al, 2014). However, changing trends in aquaculture and food consumption, as well as the use of seaweed products in food and dietary supplements could lead to significant increases in iAs exposure.…”

Citron Rho-interacting kinase mediates arsenite-induced decrease in endothelial nitric oxide synthase activity by increasing phosphorylation at threonine 497: Mechanism underlying arsenite-induced vascular dysfunction

“…Arsenic, in particular its trioxide, has been a consistent and serious threat to human health worldwide because excessive levels exist naturally in well water, groundwater and food supplies [1][2][3][4]. Several epidemiological studies have shown that chronic (and perhaps acute) exposure to arsenite is associated with increased risk for a variety of human diseases, including cardiovascular diseases (CVD) like arteriosclerosis, hypertension, and blackfoot disease [5].…”

Seaweed and seaweed-containing foods in the UK: focus on labeling, iodine content, toxicity and nutrition

“…Health promoting properties combined with the expansion of the health-food industry have led the transition of seaweed from traditional to functional ingredient (2) .With recent emphasis on iodine insufficiency in the British female population (3)(4)(5) , the potential of seaweed as a rich source of iodine has been further explored (6) . However, seaweed consumption can be associated with toxicity from high iodine intake, potential accumulation of arsenic, heavy metals and contaminants (7) . Here, we surveyed the current retail level of seaweed and edible algae in the UK market, either as whole foods or ingredients, with particular focus on labeling and iodine content.…”