Mycotoxins in a changing global environment--a review.

Mycotoxins are toxic metabolites produced by fungal species that commonly contaminate staple foods and feeds. They represent an unavoidable problem due to their presence in globally consumed cereals such as rice, maize and wheat. Most mycotoxins are immunosuppressive agents and some are carcinogens, hepatotoxins, nephrotoxins, and neurotoxins. Worldwide trends envision a stricter control of mycotoxins, however, the changing global environment may not be the ideal setting to control and reduce the exposure to these toxins. Although new technologies allow us to inspect the multi-mycotoxin presence in foods, new sources of exposure, gaps in knowledge of mycotoxins interactions, appearance of "emergent" mycotoxins and elucidation of consequent health effects can complicate their control even more. While humans are adapting to cope with environmental changes, such as food scarcity, decreased food quality, mycotoxin regulations, crop production and seasonality, and other climate related modifications, fungal species are also adapting and increased cases of mycotoxin adverse health effects are likely to occur in the future. To guarantee access to quality food for all, we need a way to balance global mycotoxin standards with the realistic feasibility of reaching them, considering limitations of producers and designing strategies to reduce mycotoxin exposure based on sound research.

Calcium montmorillonite clay reduces urinary biomarkers of fumonisin B1 exposure in rats and humans.

Fumonisin B1 (FB1) is often a co-contaminant with aflatoxin (AF) in grains and may enhance AF's carcinogenicity by acting as a cancer promoter. Calcium montmorillonite (i.e. NovaSil, NS) is a possible dietary intervention to help decrease chronic aflatoxin exposure where populations are at risk. Previous studies show that an oral dose of NS clay was able to reduce AF exposure in a Ghanaian population. In vitro analyses from our laboratory indicated that FB1 (like aflatoxin) could also be sorbed onto the surfaces of NS. Hence, our objectives were to evaluate the efficacy of NS clay to reduce urinary FB1 in a rodent model and then in a human population highly exposed to AF. In the rodent model, male Fisher rats were randomly assigned to either FB1 control, FB1 + 2% NS or absolute control group. FB1 alone or with clay was given as a single dose by gavage. For the human trial, participants received NS (1.5 or 3 g day⁻¹) or placebo (1.5 g day⁻¹) for 3 months. Urines from weeks 8 and 10 were collected from the study participants for analysis. In rats, NS significantly reduced urinary FB1 biomarker by 20% in 24 h and 50% after 48 h compared to controls. In the humans, 56% of the urine samples analysed (n = 186) had detectable levels of FB1. Median urinary FB1 levels were significantly (p < 0.05) decreased by >90% in the high dose NS group (3 g day⁻¹) compared to the placebo. This work indicates that our study participants in Ghana were exposed to FB1 (in addition to AFs) from the diet. Moreover, earlier studies have shown conclusively that NS reduces the bioavailability of AF and the findings from this study suggest that NS clay also reduces the bioavailability FB1. This is important since AF is a proven dietary risk factor for hepatocellular carcinoma (HCC) in humans and FB1 is suspected to be a dietary risk factor for HCC and oesophageal cancer in humans.

In vitro evaluation of ferrihydrite as an enterosorbent for arsenic from contaminated drinking water.

Arsenic (As) is a toxic trace element found in groundwater due to natural and industrial processes. Exposure has been linked to cancers of the bladder, lungs, skin, kidneys, nasal passages, liver, and the prostate. Arsenic in drinking water is a problem in many countries, notably Bangladesh and Taiwan. The purpose of this research was to utilize binding isotherms, a simulated gastrointestinal (GI) model, and the adult Hydra bioassay to evaluate ferrihydrite's potential to bind As and serve as a potential enterosorbent for As found in drinking water. A variety of clay minerals and synthesized iron oxides including ferrihydrite were screened for their ability to bind As(III), as sodium arsenite, and As(V), as sodium arsenate. After ferrihydrite was demonstrated to be the most effective sorbent for both As species, adsorption isotherms were performed. All isotherm data were fit to the Langmuir equation to determine adsorption capacity (Qmax). Ferrihydrite bound 96% of As(III) and 97% of As(V) in the screening studies and had a Qmax of 1.288 mol/kg for As(III) and 0.744 mol/kg for As(V). Using a simulated GI model, ferrihydrite was found to effectively adsorb As(V) and As(III) in the stomach and intestine. Ferrihydrite (0.25% w/w) protected adult Hydra at levels up to 200 times the minimal effective concentration (MEC) for As(III) and up to 2.5 times the MEC for As(V). These experiments confirm that ferrihydrite is a high capacity sorbent of As and that it is effective at removing As in a simulated GI model. These results suggest that ferrihydrite could be used as a potential enterosorbent for As found in drinking water. Future work will focus on verifying ferrihydrite's safety and efficacy in vivo.