No abstract

Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM-202 and 203) and two precipitated (NM-200 and -201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)-modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose-dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells.

Due to several gaps remaining in the toxicological evaluation of nanomaterials (NMs), consumers and public health agencies have shown increasing concern for human health protection. In addition to aluminum (Al) microparticles, Al-containing nanomaterials (Al NMs) have been applied by food industry as additives and contact materials. Due to the limited amount of literature on the toxicity of Al NMs, this study aimed to evaluate the in vivo genotoxic potential of Al 0 and Al 2 O 3 NMs after acute oral exposure. Male Sprague-Dawley rats were administered three successive gavages at 6, 12.5 and 25 mg/kg bw. A comparison with AlCl 3 was done in order to assess the potential effect of dissolution into Al ions. Both DNA strand breaks and oxidative DNA damage were investigated in six organs/tissues (duodenum, liver, kidney, spleen, blood and bone marrow) with the alkaline and the Fpg-modified comet assays. Concomitantly, chromosomal damage was investigated in bone marrow and colon with the micronucleus assay. The comet assay only showed DNA damage with Al 2 O 3 NMs in bone marrow (BM), while AlCl 3 induced slight but non-significant oxidative DNA damage in blood. No increase of chromosomal mutations was observed after treatment with the two Al MNs either in the BM or in the colons of rats.

TiO 2 nanomaterials (NM) have a wide range of industrial applications, including their use in food products. The incorporation of these NMs in consumer products represents a clear concern for public health safety agencies and consumers, and further investigation of the potential impact of these products on human health is necessary. Indeed, since human oral exposure to TiO 2 NMs is expected to increase in the years to come, there exist legitimate concerns about the risk assessment of these nanomaterials present in food products. A considerable amount of studies investigating the adverse effects of TiO 2 NMs have focused on the genotoxic effects of these NMs, and more recently they have been classified by the International Agency for Research on Cancer (IARC) as carcinogen group 2B following inhalation studies (IARC 2010). While numerous data are available for anatase or mixes of anatase/rutile forms, the toxicity and the genotoxicity of rutile TiO 2 NMs have been rarely investigated. The aim of our study was therefore to investigate the cytotoxic and genotoxic effects of two rutile TiO 2 NMs, differing in surface coating, NM103 (hydrophobic) and NM104 (hydrophilic), on intestinal and hepatic cell models. Following 3 or 24 h treatments with concentrations of TiO 2 NMs from 1.2 to 80 µg/cm 2 , we have assessed the genotoxicity of these NMs with H2AX, alkaline comet assay and micronucleus (MN) assays. Cellular viability and effects on oxidative stress were also evaluated. Although TEM imaging demonstrated the presence of the two TiO 2 NMs within the cytoplasm, no significant cytotoxic or genotoxic were observed in either cell model. We have also evaluated and taken into account a variety of potential sources of interference of NMs with cellular assays. TiO 2 NMs present in the cytoplasm introduce uncertainty in the scoring of micronuclei, and therefore this assay is not recommended for the evaluation of the genotoxicity of TiO 2 NMs, or other NMs demonstrating similar interference. The unique properties of TiO 2 NMs introduce additional complexity for genotoxicity testing, and caution must be taken in order to obtain reliable results necessary for accurate hazard assessment.

Human poisoning due to consumption of seafood contaminated with phycotoxins is a worldwide problem, and routine monitoring programs have been implemented in various countries to protect human consumers. Following successive episodes of unexplained shellfish toxicity since 2005 in the Arcachon Bay on the French Atlantic coast, a national research program was set up to investigate these atypical toxic events. Part of this program was devoted to fit-for-purpose cell-based assays (CBA) as complementary tools to collect toxicity data on atypical positive-mouse bioassay shellfish extracts. A collaborative study involving five laboratories was conducted. The responses of human hepatic (HepG2), human intestinal (Caco2), and mouse neuronal (Neuro2a) cell lines exposed to three known lipophilic phycotoxins-okadaic acid (OA), azaspiracid-1 (AZA1), and pectenotoxin-2 (PTX2)-were investigated. A screening strategy composed of standard operating procedures and a decision tree for dose-response modeling and assay validation were designed after a round of "trial-and-error" process. For each toxin, the shape of the concentration-response curves and the IC(50) values were determined on the three cell lines. Whereas OA induced a similar response irrespective of the cell line (complete sigmoid), PTX2 was shown to be less toxic. AZA1 induced cytotoxicity only on HepG2 and Neuro2a, but not on Caco2. Intra- and inter-laboratory coefficients of variation of cell responses were large, with mean values ranging from 35 to 54 % and from 37 to 48 %, respectively. Investigating the responses of the selected cell lines to well-known toxins is the first step supporting the use of CBA among the panel of methods for characterizing atypical shellfish toxicity. Considering these successful results, the CBA strategy will be further applied to extracts of negative, spiked, and naturally contaminated shellfish tissues.