Identification of the main pesticide residue mixtures to which the French population is exposed.

Owing to the intensive use of pesticides and their potential persistence in the environment, various pesticide residues can be found in the diet. Consumers are therefore exposed to complex pesticide mixtures which may have combined adverse effects on human health. By modelling food exposure to multiple pesticides, this paper aims to determine the main mixtures to which the general population is exposed in France. Dietary exposure of 3337 individuals from the INCA2 French national consumption survey was assessed for 79 pesticide residues, based on results of the 2006 French food monitoring programmes. Individuals were divided into groups with similar patterns of co-exposure using the clustering ability of a Bayesian nonparametric model. In the 5 groups of individuals with the highest exposure, mixtures are formed by pairs of pesticides with correlations above 0.7. Seven mixtures of 2-6 pesticides each were characterised. We identified the commodities that contributed the most to exposure. Pesticide mixtures can either be components of a single plant protection product applied together on the same crop or be from separate products that are consumed together during a meal. Of the 25 pesticides forming the mixtures, two--DDT and Dieldrin--are known persistent organic pollutants. The approach developed is generic and can be applied to all types of substances found in the diet in order to characterise the mixtures that should be studied first because of their adverse effects on health.

The PERICLES research program: an integrated approach to characterize the combined effects of mixtures of pesticide residues to which the French population is exposed.

Due to the broad spectrum of pesticide usages, consumers are exposed to mixtures of residues, which may have combined effects on human health. The PERICLES research program aims to test the potential combined effects of pesticide mixtures, which are likely to occur through dietary exposure. The co-exposure of the French general population to 79 pesticide residues present in the diet was first assessed. A Bayesian nonparametric model was then applied to define the main mixtures to which the French general population is simultaneously and most heavily exposed. Seven mixtures made of two to six pesticides were identified from the exposure assessment. An in vitro approach was used for investigating the toxicological effects of these mixtures and their corresponding individual compounds, using a panel of cellular models, i.e. primary rat and human hepatocytes, liver, intestine, kidney, colon and brain human cell lines. A set of cell functions and corresponding end-points were monitored such as cytotoxicity, real-time cell impedance, genotoxicity, oxidative stress, apoptosis and PXR nuclear receptor transactivation. The mixtures were tested in equimolar concentrations. Among the seven mixtures, two appeared highly cytotoxic, five activated PXR and depending on the assay one or two were genotoxic. In some experiments, the mixture effect was quantitatively different from the effect expected from the addition concept. The PERICLES program shows that, for the most pesticides mixtures to which the French general population is exposed, the toxic effects observed on human cells cannot be easily predicted based on the toxic potential of each compound. Consequently, additional studies should be carried on in order to more accurately define the mixtures of chemicals to which the consumers are exposed, as well as to improve the investigation, prediction and monitoring of their potential human health effects.

Assessment of dietary exposure of nitrate and nitrite in France.

The aim of this study was to assess the dietary exposure of nitrate and nitrite in France. A total of 13, 657 concentration levels of nitrate and nitrite measured in food, representing 138 and 109 food items, respectively, and coming from French monitoring programmes between 2000 and 2006, were used. Depending on the non-detected and non-quantified analysis treatment, lower and upper concentration mean estimates were calculated for each food item. These were combined with consumption data derived from 1474 adults and 1018 children from the French national individual consumption survey (INCA1), conducted in 1999 and based on a 7-day food record diary. A total of 18% of spinaches, 6% of salads, 10% of cheeses, 8% of meat products and 6% of industrial meat products exceeded the European nitrate maximum level or maximum residual level. A total of 0.4% of industrial meat products and 0.2% of meat products exceeded their European nitrite maximum level or maximum residual level. Nitrate dietary exposure averaged 40% of the acceptable daily intake (ADI; 3.7 mg kg(-1) body weight day(-1)) for adults and 51 - 54% of the ADI for children with the major contributors being, for adults and children, respectively, vegetables (24 and 27% of ADI), potatoes (5 and 11% of ADI), and water (5 and 5% of ADI). The individual nitrate dietary intake of 1.4% (confidence interval (CI(95th)) [0.8; 2.0]) to 1.5% (CI(95th) [0.9; 2.1]) of adults and 7.9% (CI(95th) [6.2; 9.6]) to 8.4% (CI(95th) [6.7; 10.1]) of children were higher than the ADI. Nitrite dietary exposure averaged 33-67% of the ADI (0.06 mg kg(-1) body weight day(-1)) for adults and 67-133% of the ADI for children, with contributions of additive food vectors at 33% of ADI for adults and 50-67% of ADI for children. The individual nitrite dietary intake of 0.7% (CI(95th) [0.3; 1.1]) to 16.4% (CI(95th) [14.5; 18.3]) of adults and 10.5% (CI(95th) [8.6; 12.4]) to 66.2% (CI(95th) [63.3; 69.1]) of children were higher than the ADI.

Natural chondroitin sulphates increase aggregation of proteoglycan complexes and decrease ADAMTS-5 expression in interleukin 1 beta-treated chondrocytes.

OBJECTIVE: To assess the effect of natural chondroitin sulphate (CS) on the ability of neosynthesized sulphated proteoglycans (PGs) to aggregate in cultured chondrocytes treated with interleukin (IL)1 beta. METHODS: Primary cultured rabbit articular chondrocytes were treated or not with IL1 beta alone or with concentrations of CS for 20 h. Neosynthesized PGs were labelled by incorporation of [35SO(4)]-sulphate and analysed by chromatography on Sepharose 2B columns. Gelatinolytic activity was measured by zymography, and matrix metalloproteinase (MMP)1 mRNA level in chondrocytes underwent real-time PCR. Expression of ADAMTS (for "a disintegrin and metalloproteinase with thrombospondin motifs") -4 and -5 was analysed by real-time PCR and western blotting. RESULTS: The production of [35SO(4)]-labelled PGs was significantly increased with 10 microg/ml CS in the cellular pool rather than in the incubation medium. The addition of CS to IL1 beta-treated cells inhibited in part the disaggregation of sulphated PGs induced by IL1 beta. This inhibitory effect of CS is associated with a significant decrease in ADAMTS-5 expression at the mRNA and protein levels. No effect of CS was observed on IL1 beta-induced gelatinolytic activity, MMP1 mRNA expression or ADAMTS-4 expression. CONCLUSION: CS increases the production of functional sulphated PGs in the direct environment of chondrocytes in vitro. This beneficial effect of CS in IL1 beta-treated cells is associated with decreased expression of ADAMTS-5.

Copper modulation of extracellular matrix synthesis by human articular chondrocytes.

OBJECTIVE: The effects of Cu2+ on human articular chondrocytes, arising from both N (normal) and OA (osteoarthritic) cartilage, were investigated "in vitro". METHODS: Chondrocytes, cultured in high density, were incubated with copper chloride (0.01-0.25 microM/mL). Proteoglycan and collagen were assessed by incorporation of [35S]-Sulfate and [3H]-Proline. SDS-PAGE analysis was performed to quantify the ratio of type II to type I collagen. RESULTS: Cu2+ neither increased proteoglycan synthesis by chondrocytes. of origin N or OA, nor influenced their proliferation rate. Collagen synthesis was increased. This effect is time and concentration dependant: in cultures treated for 12 days, collagen synthesis stimulation was +20% and +26% (P < 0.02) in N and OA cultures respectively, the ratio of type II to type I collagen was slightly increased. This effect was more obvious in OA cell lines than in N ones. CONCLUSION: The observations suggest that Cu2+ upregulates collagen anabolism in human articular chondrocytes.

Apoptosis in normal and osteoarthritic human articular cartilage.

OBJECTIVES: To investigate whether apoptosis occurs in osteoarthritis (OA), and if this phenomenon is modulated by human recombinant interleukin 1beta (hrIL1beta). METHODS: Human articular cartilage samples were obtained at the time of hip arthroplasty because of femoral neck fracture (normal cartilage) (n=4) or advanced coxarthrosis (OA cartilage) (n=14). Apoptotic chondrocytes, isolated by collagenase digestion and cultivated for 24 hours, or present in situ in frozen cartilage sections, were quantified by fluorescent microscopy using two apoptosis markers: the TUNEL reaction, which detects nuclear DNA fragmentation, and Annexin-V-fluos, which labels at the membrane level the externalisation of phosphatidylserine. RESULTS: In OA cartilage 18-21% of chondrocytes showed apoptotic features, compared with 2-5% in normal cartilage. The results were similar for the two comparative studies (in situ and in vitro) and for both apoptosis markers. Moreover, hrIL1beta increased the apoptosis rate in vitro in a dose dependent manner in OA and normal chondrocytes. CONCLUSION: These results suggest that apoptosis may be an important factor in the evolution of OA and may be a new target for treatment of OA.