Impact of a risk-benefit advisory on fish consumption and dietary exposure to methylmercury in France.

We designed the CORAI (COnsumer Risk Advisory Inquiry) study to observe consumer reactions' after an advisory revealing risk of methylmercury contamination together with benefits of Long-Chain Poly Unsaturated Fatty Acids of the n-3 variety (LC n-3 PUFA). The message was very close to the ones commonly delivered by national food agencies and included recommendations for women of childbearing age and children below 15 years old. Two groups of subjects including consumers at risk were selected. Participants recorded the frequency of their fish consumption detailed by species for them and their family over a one-month period one month before, a month immediately after and 3 month after the advisory. Results were compared between consumers receiving the advisory and controls. Results show that the message revelation led to a significant decrease in total fish consumption which is greater for children below 6 years old than for the children between 6 and 15 years old and women. The consumption of the most contaminated fish quoted in the advisory, rarely consumed and poorly known by French consumers did not decrease in any group despite the advice to avoid their consumption. The consumption of other fish products quoted in the advisory but frequently consumed and better known, as canned tuna, did decrease and was a major contributor to the overall reduction of exposure for the advised group. Before the information, about 3% of women of childbearing age are exceeding the PTWI for MeHg and both the average and the high percentiles of the exposure to MeHg are decreasing significantly in the advised group. Regarding the number of subjects of the advised group exceeding the PTWI, they were 6, 3 and 2, respectively, in May, June and September. Accompanying questionnaires show that consumers imperfectly memorize most of the fish species quoted in the recommendation. This paper concludes that consumer advisory, which is a major tool for risk management, has a minimal effect under our experimental conditions to reduce the exposure of groups at risk. Messages to be carried to consumers should be carefully tested for long term memorization in order to become more effective.

Application of laser scanning cytometry followed by epifluorescent and differential interference contrast microscopy for the detection and enumeration of Cryptosporidium and Giardia in raw and potable waters.

AIMS: The main goal of this study was to validate a new laser scanning cytometry method (ChemScanRDI) that couples immunofluorescence detection with differential interference contrast (DIC) confirmation, against manual microscopic enumeration of Giardia and Cryptosporidium (oo)cysts. This study also assessed the basic performance of the new Association Française de Normalisation (AFNOR) NF T 90-455 method for Giardia and Cryptosporidium (oo)cyst enumeration with respect to (oo)cyst yield, linearity, repeatability, influence of turbidity and detection limit in raw and potable waters. METHODS AND RESULTS: The new standard method relies on cartridge (Envirocheck) filtration, immunomagnetic separation purification, immunofluorescence staining and detection followed by DIC confirmation. The recovery was 30-50% for both parasites at seeding levels from 30 to 230 (oo)cysts. The method is linear from 0 to around 400 seeded (oo)cysts and the yield does not significantly vary for turbidity levels from 10 to 40 Formazin Nephelometric Units (FNU). The results were obtained using manual microscopic enumeration of the (oo)cysts. The ChemScanRDI yielded counts that were at least equivalent to those obtained using manual microscopy for both parasites in raw and potable water concentrates, for seeding levels of 10-300 or 10-100, respectively. The purification and labelling method proposed by the supplier of theChemScanRDI (Chemunex) reached very similar recoveries to the AFNOR protocol (70-86% in both cases). CONCLUSIONS: Laser scanning cytometry can be used as a more standardized alternative to manual enumeration as part of the new AFNOR standard method. SIGNIFICANCE AND IMPACT OF THE STUDY: By using laser scanning cytometry instead of manual microscopy, laboratories could circumvent the limitations of manual microscopy, namely: low sample throughput, operator subjectivity and operator fatigue. The study further supports the drive to incorporate laser scanning cytometry in the standard methods for Giardia and Cryptosporidium enumeration.