Associations of per- and polyfluoroalkyl substances (PFAS) and their mixture with risk of rheumatoid arthritis in the U.S. adult population.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are known environmental contaminants with immunosuppressive properties. Their connection to rheumatoid arthritis (RA), a condition influenced by the immune system, is not well studied. This research explores the association between PFAS exposure and RA prevalence. METHODS: This research utilized data from the NHANES, encompassing a sample of 10,496 adults from the 2003-2018 cycles, focusing on serum levels of several PFAS. The presence of RA was determined based on self-reports. This study used multivariable logistic regression to assess the relationship between individual PFAS and RA risk, adjusting for covariates to calculate odds ratios (ORs). The combined effects of PFAS mixtures were evaluated using BKMR, WQS regression, and quantile g-computation. Additionally, sex-specific associations were explored through stratified analysis. RESULTS: Higher serum PFOA (OR = 0.88, 95% CI: 0.79, 0.98), PFHxS (OR = 0.91, 95% CI: 0.83, 1.00), PFNA (OR = 0.87, 95% CI: 0.77, 0.98), and PFDA (OR = 0.89, 95% CI: 0.81, 0.99) concentration was related to lower odds of RA. Sex-specific analysis in single chemical models indicated the significant inverse associations were only evident in females. BKMR did not show an obvious pattern of RA estimates across PFAS mixture. The outcomes of sex-stratified quantile g-computation demonstrated that an increase in PFAS mixture was associated with a decreased odds of RA in females (OR: 0.76, 95% CI: 0.62, 0.92). We identified a significant interaction term of the WQS*sex in the 100 repeated hold out WQS analysis. Notably, a higher concentration of the PFAS mixture was significantly associated with reduced odds of RA in females (mean OR = 0.93, 95% CI: 0.88, 0.98). CONCLUSIONS: This study indicates potential sex-specific associations of exposure to various individual PFAS and their mixtures with RA. Notably, the observed inverse relationships were statistically significant in females but not in males. These findings contribute to the growing body of evidence indicating that PFAS may have immunosuppressive effects.

[δ¹5N-NO3⁻ and δ¹8O-NO3⁻ Tracing of Nitrate Sources in Beijing Urban Rivers].

In order to quantitatively identify sources of nitrate pollution in Beijing urban area and provide effective guidance for relevant departments to control the pollution of Beijing rivers, δ¹5N-NO3⁻ and δ¹8O-NO3⁻ isotope tracing method was used to analyze the composition of nitrogen and oxygen stable isotopes from nitrate in Beijing urban river. Besides, stable isotope mixing model was adopted to track nitrogen sources of nitrate in Beijing urban rivers and the contribution rates of respective pollution sources were evaluated. The results showed that: (1) NO3⁻-N pollution was the main inorganic nitrogen pollution in Beijing rivers and pollution of downstream was more serious than that of upstream. (2) δ¹5N-NO3⁻ in Beijing urban surface rivers was in range of 6.26 per thousand-24.94 per thousand, while δ¹8O-NO3⁻ ranged -0.41 per thousand-11.74 per thousand; δ¹5N-NO3⁻ increased from upstream to downstream along the flow of the surface water. (3) The nitrate pollution composition of Beijing rivers could be gained from the stable isotope mixing model. The average contribution rates of manure and sewage, soil nitrate and atmospheric deposition were 61.2%, 31.5% and 7.3%, respectively.

[Characteristics of Total Nitrogen and Total Phosphorus Pollution and Eutrophication Assessment of Secondary River in Urban Chongqing].

To understand the secondary river quality in Chongqing urban area, six typical secondary rivers were chosen to investigate the pollution characteristics of total nitrogen and total phosphorus and to evaluate the water eutrophication level according to the monitoring data of water physicochemical characteristics and chlorophyll content from April 2013 to March 2014. The study results showed that: the six rivers mentioned above have been seriously polluted by TN and TP, with the monthly mean values of TN and TP far exceeding the universally accepted threshold values of water eutrophication. Water eutrophicaton appraisal result indicated that all rivers in each season were in a state of eutrophication, and the eutrophication level could be arranged in the order of Panxi River > Qingshui River > Tiaodeng River > Huaxi River > Funiu River > Chaoyang River. The seasonal changes in TN and TP of secondary rivers were significant, with high concentrations of TN and TP in spring and winter, and lower concentrations in summer and autumn. TN and TP of the rivers showed a trend of increasing from the upstream to the downstream in each season. Pollutant concentration accumulated gradually along rivers and the maximum accumulation rate reached 1. 25 mg . (L . km) -1. Therefore, further study on urban secondary river pollution characteristics is of great significance to urban water pollution control.