Risk-benefit assessment of methylmercury and n-3 polyunsaturated fatty acids through fish intake by pregnant women in Shanghai, China: Findings from the Shanghai Diet and Health Survey.

BACKGROUND: Fish and shellfish contain nutrients essential for fetal health, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The concern of mercury (Hg) pollution limits fish consumption among women in pregnancy, which could adversely affect child development. This study aimed to conduct risk-benefit assessment and provide recommendations for fish intake by pregnant women in Shanghai, China. METHODS: Secondary analysis was conducted using cross-sectional data from a representative sample of the Shanghai Diet and Health Survey (SDHS) (2016-2017), China. Dietary intakes of Hg and DHA + EPA were calculated from the food frequency questionnaire (FFQ) on fish items and 24hr recall record. Raw fish samples (59 common species of fish in Shanghai) were purchased in local markets and their concentrations of DHA, EPA and Hg were measured. Net IQ points gain was used to evaluate the health risk and benefit at a population level by FAO/WHO model. Recommended fish (i.e., high- DHA + EPA and low-level MeHg) were defined, and then the proportion of those hit 5.8 IQ points were simulated with their consumption frequency for 1, 2 and 3 times per week. RESULTS: The average consumption of fish and shellfish was 66.24 g/d among pregnant women in Shanghai. The mean concentrations of Hg and EPA + DHA in fish species most commonly consumed in Shanghai were 0.179 mg/kg and 0.374 g/100 g, respectively. Only 1.4% of the population exceeded the MeHg reference dose of 0.1 µg/kg·bw/d, whereas 81.3% of those who did not meet the recommended daily intakes of 250 mg EPA + DHA. In FAO/WHO model, the proportion of 28.4% reached the maximum IQ points gain. Along with the increase of "recommended fish" consumed, the simulated values of the proportion raised to 74.5, 87.3 and 91.9%, respectively. CONCLUSION: The pregnant women in Shanghai, China had an adequate fish consumption with low-level Hg exposure, but balancing the benefits of fish intake and risk of potential Hg exposure was still a challenge. It is necessary to define a local level of "recommended fish" consumption for developing dietary recommendations for pregnant women.

Estimation of the bio-accessibility of methylmercury from aquatic foods using a PBTK model with an approximate Bayesian computation method in Chinese pregnant women.

BACKGROUND: Fish are the primary source of protein and docosahexaenoic acid (DHA) for pregnant women and children, but methylmercury (MeHg) pollution is the potential hazard of fish consumption. In risk assessments, the bio-accessibility of MeHg is usually assumed to be 100%, which could lead to overestimation of dietary exposure. METHOD: An existing PBTK model was adapted to estimate parameters of the bio-accessibility based on MeHg exposure data from a cohort of 397 Chinese pregnant women. The posterior distributions of parameters were determined by using the ABC - MCMC. RMSEP and Spearman's rank correlation coefficients (Rho) were calculated to determine the goodness of model fitting. The Monte Carlo analysis was performed for the parameter distributions to estimate the model variability. RESULT: The median of daily MeHg intake and maternal MeHg levels were 0.018 µg/kg bw and 3.01 µg/kg in the early and middle terms of pregnancy. The estimated bio-accessibility of freshwater fish, marine fish and others were 46.1, 17.3 and 58.2%, separately. The RMSEP improved from 11.18 to 2.54 and the Rho improved from 0.19 to 0.22 after bio-accessibility optimization. The model variability was estimated to be 2.6. CONCLUSION: The bio-accessibility estimated in this study was comparable to that determined in previous in vitro studies. The optimized model could improve the prediction performance on the MeHg body burden by dietary exposure.

Dose-response evaluation of urinary cadmium and kidney injury biomarkers in Chinese residents and dietary limit standards.

BACKGROUND: Cadmium (Cd) is a common heavy metal that mainly causes renal damage. There is a lack of research on the large-scale and systematic evaluation of the association between urinary Cd (U-Cd) and various effect biomarkers among Chinese residents. METHODS: Based on the establishment process of dietary Cd limit standards by European Food Safety Authority (EFSA), the dose-response relationships between U-Cd and four biomarkers, ß2-microglobulin (ß2-MG), N-acetyl-ß-glucosidase (NAG), microalbumin (mALB), and retinol binding Protein (RBP) were explored, respectively. Toxicokinetic model was used to derive the dietary Cd exposure limit for Chinese residents after critical U-Cd concentration was calculated. RESULTS: As the sensitive biomarkers of renal injury, ß2-MG and NAG were selected to estimate the 95% confidence interval lower limit of the U-Cd benchmark dose (BMDL5) to be 3.07 and 2.98 µg/g Cr, respectively. Dietary Cd exposure limit was calculated to be 0.28 µg/kg bw/day (16.8 µg/day, based on the body weight of 60 kg), which was lower than the average Chinese Cd exposure (30.6 µg/day) by the China National Nutrient and Health Survey. CONCLUSION: This study established an overall association between U-Cd and renal injury biomarkers, and explored the Chinese dietary Cd exposure limits, which helps improve Chinese Cd exposure risk assessment and provides a reference basis for formulating reasonable exposure standards.

Bayesian toxicokinetic modeling of cadmium exposure in Chinese population.

Cadmium (Cd) is a toxic heavy metal widely present in the environment. Estimating its internal levels for a given external exposure using toxicokinetic (TK) models is key to the human health risk assessment of Cd. In this study, existing Cd TK models were adapted to develop a one-compartment TK model and a multi-compartment physiologically based toxicokinetic (PBTK) model by estimating the characteristics of Cd kinetics based on Cd exposure data from 814 Chinese residents. Both models not only considered the effect of gender difference on Cd kinetics, but also described the model parameters in terms of distributions to reflect individual variability. For both models, the posterior distributions of sensitive parameters were estimated using the Markov chain-Monte Carlo method (MCMC) and the approximate Bayesian computation-MCMC algorithm (ABC-MCMC). Validation with the test dataset showed 1.4-22.5% improvement in the root mean square error (RMSE) over the original models. After a systematic literature search, the optimized models showed acceptable prediction on other Chinese datasets. The study provides a method for parameter optimization of TK models under different exposure environment, and the validated models can serve as new quantitative assessment tools for the risk assessment of Cd in the Chinese population.

Modes of Transport to School and Their Associations with Weight Status: A Cross-Sectional Survey of Students in Shanghai, China.

Background: Over the past two decades, both transport modes as well as overweight/obesity have changed dramatically among students in China, but their relationships are not clear. This study aimed to investigate modes of transport to school and their associations with the weight status of Chinese students. Methods: A cross-sectional study was conducted with non-resident students aged 6 to 17 years from all 16 districts across Shanghai, China in October and November 2019. Information about sociodemographic characteristics and the models of travel to school among students was investigated using an online, self-administered, structured questionnaire (or those assisted by their parents). Weight and height were measured by school health workers, and the Chinese standard age adjusted BMI (weight/height2) was used to classify students' weight status. Cumulative logistic regression modelling was used to examine the relationships. Results: The main mode of transport to school was an active mode (46.5%, defined as walking, bicycling, or public transport), followed by an inactive mode of transport (30.5%, defined as a car or bicycle as a passenger), and a combination of both modes (23%). About one-third of the students were overweight or obese and 5% were underweight. No statistically significant association between transport modes and weight status was found in this study. Conclusions: In Shanghai, close to one-third of children travel to school by an inactive mode of transport. The findings of this study did not support the notion that an active mode to school could be beneficial for preventing overweight/obesity in students in China.

Cancer risk and disease burden of dietary cadmium exposure changes in Shanghai residents from 1988 to 2018.

Cadmium (Cd) is a widely distributed toxic metal, which is mainly exposed to humans through diet. The impact of dietary guidelines on the Chinese diet structure has indirectly led to changes in dietary Cd exposure. The Chinese Dietary Guidelines were issued in 1997 and revised in 2007. Based on the time between issuance and revision, this study examined the Cd contamination levels in Shanghai foods from 1988 to 2018 and evaluated cancer risk and disease burden of dietary Cd exposure accordingly. Over the time periods of 1988-1997, 1998-2007, and 2008-2018, it was found that Cd dietary exposure of Shanghai residents showed a trend of increasing and then decreasing (39.7, 44.7, and 36.4 µg/day, respectively). In contrast to cereals, the contribution rates of meat and vegetables to Cd exposure have gradually increased over time, and aquatic foods have become the main source of Cd exposure (40.6%). Although the non-cancer risk hazard quotients of dietary Cd exposure and the excess lifetime cancer risks (ELCR) are relatively low (HQ < 1, ELCR < 10-4), 26.6% of Shanghai residents had a potential risk of kidney injury calculated by toxicokinetic model (TK model), and the disability adjusted life years (DALYs) have been rising (from 41.6 to 58.2). Results indicated that in the past three decades, changes of Cd contamination in food due to both limit standards and changes in dietary structure have influenced cancer risk and disease burden from Cd exposure in Shanghai residents. In summary, our study suggested that while regulating the contamination in foods, attention should also be paid to the potential impacts of dietary structure and guidelines on the exposure of pollutants.