AIM: To improve the efficacy of intercalating dyes to distinguishing between infectious and inactivated hepatitis A virus (HAV) in food. METHODS AND RESULTS: Different intercalating dyes were evaluated for the discrimination between infectious and thermally inactivated HAV suspensions combining with the RT‐qPCR proposed in the ISO 15216. Among them, PMAxx was the best dye in removing the RT‐qPCR signal from inactivated HAV. Applied to lettuce and spinach, PMAxx–Triton pretreatment resulted in complete removal of the RT‐qPCR signal from inactivated HAV. Likewise, this study demonstrates that this pretreatment is suitable for the discrimination of inactivated HAV in shellfish without further sample dilution. In mussels and oysters, the developed viability RT‐qPCR method reduced the signal of inactivated HAV between 1·7 and 2·2 logs at high inoculation level, and signal was completely removed at low inoculation level. CONCLUSIONS: This study showed that the use of PMAxx is an important improvement to assess HAV infectivity by RT‐qPCR. It was shown that PMAxx–Triton pretreatment is suitable for the analysis of infectious HAV in complex food samples such as vegetables and shellfish. SIGNIFICANCE AND IMPACT OF THE STUDY: The PMAxx–Triton pretreatment can be easily incorporated to the ISO norm for infectious virus detection.

Aquaculture, which is growing 3–5 times faster than terrestrial agriculture, will play an important role to meet future global food production needs. However, over 80% of global sewage production is returned to the environment untreated or poorly treated. In developing nations, these nontraditional waters of diverse quality are being recycled for aquaculture, yet chemical residues are differentially studied. Here, we examined pharmaceuticals, pesticides, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and flame retardants in marine bivalves using isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and low-pressure gas chromatography-tandem mass spectrometry (LP GC-MS/MS). Green-lipped mussels from the field and oysters from aquaculture net pens, which are harvested as food products, were collected adjacent to point source municipal wastewater and landfill leachate effluent discharges, respectively, in Hong Kong, the fourth most densely populated country in the world. Multiple classes of pharmaceutical, pesticides, PAHs, and phosphorus-based flame retardants were detected at low μg/kg levels. Acceptable servings per week indicated minimal risk for a number of chemicals; however, such calculations could not be performed for other contaminants of emerging concern. Future efforts are needed to better understand contaminant influences on marine bivalve populations and aquaculture product safety, particularly in rapidly urbanizing regions of developing countries with limited wastewater infrastructure.

Global climate change is expected to have multiple impacts on food and water safety. Knowledge synthesis methods can provide a credible and robust assessment of the evidence on these potential impacts to inform risk assessments. To illustrate the utility of these methods to synthesize data for a case study scenario of one of the potential impacts of climate change on food safety, and to inform a complementary risk assessment model, we conducted a systematic review of the effects of water temperature and salinity on Vibrio parahaemolyticus in raw oysters and harvest waters. We searched four bibliographic databases for literature then two independent reviewers screened 953 citations for relevance and extracted data from 120 relevant articles. Sufficient data for meta-analysis were provided in 19 articles. Random-effects meta-analysis, a quality-of-evidence assessment, and meta-regression (where applicable) were conducted on unique data subsets reporting correlation coefficients for the relationships of interest. A positive correlation was identified between water temperature and V. parahaemolyticus in oysters (r=0.58; 95% CI: 0.47 to 0.68) and water (r=0.60; 95% CI: 0.47 to 0.70). However, both analyses were significantly heterogeneous (I2=74% and I2=75%, respectively), which was not explained by the variables evaluated in meta-regression. No consistent relationship was identified for water salinity. A low and very low quality-of-evidence was identified for the water temperature and salinity relationships, irrespective of sampling media. Due to insufficient reporting and availability, we were unable to perform meta-analysis on regression coefficients for direct inclusion in the risk assessment model. However, the synthesis process provided a structured and transparent evaluation of the evidence to confirm associations between water temperature and V. parahaemolyticus densities, indicate no consistent association between salinity and V. parahaemolyticus densities, and compile available regression coefficients. Future synthesis research could evaluate other effects of climate on food and water safety to inform additional risk assessments.

The objectives of this study were to 1) determine the influence of environmental factors (water temperature, food availability [chlorophyll-a], salinity) on nacre deposition rate and tablet thickness at different positions in shells of two strains of pearl oyster, Pinctada fucata (Gould, 1850)—one from Japan, and one a Hybrid between this Japanese strain and another from China; 2) compare nacre deposition rates and tablet thickness in different shell positions within and between these two pearl oyster strains; and 3) determine relationships between shell nacre deposition rate and tablet thickness in host oysters of these two strains with those of their pearls. Nacre and tablet thickness were measured at three positions along the mantle pallial line (anterior, middle, and posterior), and one position close to the hinge, on the left valve of each oyster. Water temperature and chlorophyll-a were positively correlated (p < .001, Spearman's rho >0.75) and salinity was negatively correlated (p < .001, Spearman's rho < −0.7) with nacre deposition rate at all shell positions in both pearl oyster strains. Only water temperature below 13 °C influenced nacre tablet thinning. Significant differences in total nacre deposition occurred between the four sampling positions on the shell in both strains (p < .001), with deposition at the hinge area the slowest for both Hybrid (373.212 μm) and Japanese (569.248 μm) oysters. Nacre tablet thickness in the middle position on the shell increased most steadily over time, and was thinnest in the coolest months (0.151 μm and 0.167 μm for Hybrid and Japanese oysters, respectively). No significant difference (p > .05) in nacre tablet thickness was apparent between strains. Correlation analysis of nacre deposition rate between the shell and pearls showed that all shell positions were highly correlated with their respective pearls (p < .001, Spearman's Rho >0.75). Environmental factors influence shell nacre deposition and thickness, and because shell nacre deposition is related to pearl nacre, pearl growth also. This influence varies in different shell positions, with nacre deposition in the posterior position on the shell the fastest, and the middle position showing the most stable and thin nacre tablet. Japanese pearl oysters exhibit better nacre deposition than Hybrid oysters and would be more appropriate as host oysters in Ago Bay, Japan, should culture occur in environmental conditions comparable to those in this study.