The association between ambient PM2.5 exposure and the risk of preterm birth in China: A retrospective cohort study

BACKGROUND

The relationship between PM2.5 exposure and preterm birth remains unclear.

OBJECTIVES

To explore the effect of exposure to PM2.5 on preterm birth in China.

METHODS

The birth outcomes of 426,246 pregnant women enrolled between January 2014 and December 2014 in NFPCP (National Free Pre-pregnancy Checkups Project) were collected, and their individual PM2.5 exposure values were estimated from the China National Environmental Monitoring Centre. The time of gestational exposure to PM2.5 was divided into four periods (the first trimester, the second trimester, the third trimester and the entire pregnancy). The average concentration and the corresponding quartiles of PM2.5 were calculated in these periods by the daily average PM2.5 data. Cox proportional hazards regression was used and he effects of maternal age, education level, occupation, second-hand smoking, alcohol use, pre-pregnancy BMI, baby's sex, number of previous pregnancies, coastal areas and season of conception were adjusted for.

RESULTS

A total of 426,246 singleton births were included, among which 35,261 (8.3%) were preterm birth. Effect of each 10μg/m³ increase of PM2.5 on preterm birth was most significant during the third trimester (HR, 1.06; 95%CI, 1.06-1.07), and also significant during the first trimester (HR, 1.04; 95%CI, 1.03-1.04), the second trimester (HR, 1.02; 95%CI, 1.02-1.02) and the entire pregnancy (HR, 1.06; 95%CI, 1.05-1.06). Compared with the lowest quartile of PM2.5, other quartiles increased the risk of preterm birth, and were most significant during the third trimester (HR, 1.87; 95%CI, 1.69-2.06). Subgroup analysis showed that compared with other subgroups, women who were older than 30years, had low education level, worked as farmers, had male baby, had previous pregnancies, not live in coastal areas and pregnant in winter were more sensitive to PM2.5 exposure.

CONCLUSIONS

Ambient PM2.5 exposure during pregnancy played an important role in the pregnancy process and increased the risk of preterm birth.

The effects of maternal and children phthalate exposure on the neurocognitive function of 6-year-old children

The primary purpose of this study was to investigate the effects of phthalate exposure on the intelligence and attentional performance of 6-year old children when adjusting each other as covariates. We also investigated the differential effects of phthalate exposure on the intelligence and attention according to exposure period (maternal or children). Urine concentrations of mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-n-butyl phthalate (MBP) were analyzed. Multivariable linear regression models were used to investigate the relationship between exposure to various phthalates with IQ scores and continuous performance test (CPT) variables. There were robust associations between child MEHHP and MEOHP levels with full scale IQ (FSIQ) even after adjusting for demographic variables and CPT scores (MEHHP -9.27, 95% CI: -17.25, -1.29; MEOHP -9.83, 95% CI: -17.44, -2.21). Child MEHHP and MEHOP levels negatively affected omission errors (MEHHP -20.36, 95% CI: -34.17, -6.55; MEOHP -18.93, 95% CI: -32.58, -5.28) and the response time variability (MEHHP -21.07, 95% CI: -39.04, -3.10; MEOHP -20.41, 95% CI -38.14, -2.69) of the CPT after adjusting for demographic variables and IQ. Maternal phthalate exposure had no effects on IQ or CPT variables. These results suggest that children phthalate exposure, but not maternal exposure, has an adverse effect on IQ and attentional performance, and these associations were found to be independent of each other.

Phytotoxicity of silver nanoparticles to Lemna minor: Surface coating and exposure period-related effects

Silver nanoparticles (Ag NPs) exponential production raises concern about their environmental impact. The effects of Ag NPs to aquatic plants remain scarcely studied, especially in extended exposures. This paper aims to evaluate Ag NPs effects in Lemna minor at individual and sub-individual levels, focusing on three variables: Ag form (NPs versus ions - Ag⁺), NPs surface coating (citrate vs polyvinylpyrrolidone - PVP) and exposure period (7 vs 14days). Endpoints were assessed at individual level (specific growth rate, chlorosis incidence and number of fronds per colony) and sub-individual level (enzymatic activities of catalase (CAT), guaiacol peroxidase (GPx) and glutathione-S-transferase (GST)). Generally, plants exposed to all Ag forms underwent decays on growth rate and fronds per colony, and increases on chlorosis, GPX and GST, but no effects on CAT. The most sensitive endpoints were specific growth rate and GPx activity, showing significant effects down to 0.05mg/L for Ag NPs and 3μg/L for Ag⁺, after 14days. Ag⁺ showed higher toxicity with a 14d-EC₅₀ of 0.0037mg Ag/L. Concerning surface coating, PVP-Ag NPs were more deleterious on growth rate and fronds per colony, whereas citrate-Ag NPs affected more the chlorosis incidence and GPx and GST activities. The exposure period significantly affected chlorosis: 14days triggered a chlorosis increase in Ag⁺-exposed plants and a decrease in Ag NPs-exposed plants when compared to 7days. Ag NPs induced an oxidative stress status in cells, thus ensuing upregulated enzymatic activity as a self-defense mechanism. Since Ag NPs dissolution might occur on a steady and continuous mode along time, and the average longevity of fronds, we propose longer exposures periods than the recommended by the OECD guideline. This approach would provide more relevant and holistic evidences on the overall response of freshwater plants to Ag NPs in an ecological relevant scenario.

Toxicity of phosphine on the developmental stages of rust-red flour beetle, Tribolium castaneum Herbst over a range of concentrations and exposures

The susceptibility of the developmental stages of rust-red flour beetle, Tribolium castaneum to a range of concentrations of phosphine over varying durations from 24 to 168 h was reconnoitered in the laboratory at 25 ± 2 °C. Responses of the life stages exposed to phosphine were compared with those of un-treated controls over 24, 48, 72, 96, 120, 144 and 168 h exposures and mortality was assessed after 14 days. Among the life stages tested, pupae were more tolerant to phosphine followed by the egg and the larval instars. At 24 h, the maximum LC50 value was observed in case of egg; 1.571 mgL(-1); followed by the pupae, 6(th) instar, 4(th) instar and 2(nd) instar larvae with LC50 values of 1.184, 0.336, 0.212 and 0.081 mgL(-1) respectively. However, continued exposure of the developmental stages to phosphine, recorded maximum LC values in the pupae followed by egg and the larval instars. A linear increase in the mortality response was witnessed in all the insect stages when the exposure periods were extended from 24 to 168 h with increasing concentrations of phosphine, conversely significant increase in mortality was greatly apparent during the initial treatment periods.

Mother-level random effect in the association between PM2.5 and fetal growth: A population-based pregnancy cohort

BACKGROUND

A growing body of literature reports associations between exposure to particulate matter with diameter ≤2.5 μm (PM_2.5) during pregnancy and birth outcomes. However, findings are inconsistent across studies.

OBJECTIVES

To assess the association between PM_2.5 and birth outcomes of fetal growth in a cohort with high prevalence of siblings by multilevel models accounting for geographical- and mother-level correlations.

METHODS

In Israel, we used Maccabi Healthcare Services data to establish a population-based cohort of 381,265 singleton births reaching 24-42 weeks' gestation and birth weight of 500-5000 g (2004-2015). Daily PM_2.5 predictions from a satellite-based spatiotemporal model were linked to the date of birth and maternal residence. We generated mean PM_2.5 values for the entire pregnancy and for exposure periods during pregnancy. Associations between exposure and birth outcomes were modeled by using multilevel logistic regression with random effects for maternal locality of residence, administrative census area (ACA) and mother.

RESULTS

In fully adjusted models with a mother-level random intercept only, a 10-μg/m³ increase in PM_2.5 over the entire pregnancy was positively associated with term low birth weight (TLBW) (Odds ratio, OR = 1.25, 95% confidence interval, CI: 1.09,1.43) and small for gestational age (SGA) (OR = 1.15, 95% CI: 1.06,1.26). Locality- and ACA-level effects accounted for <0.4% of the variance while mother-level effects explained ∼50% of the variability. Associations varied by exposure period, infants' sex, birth order, and maternal pre-pregnancy BMI.

CONCLUSIONS

Consideration of mother-level variability in a region with high fertility rates provides new insights on the strength of associations between PM_2.5 and birth outcomes.

The influence of biofilm maturation on fluoride's anticaries efficacy

OBJECTIVES

(1) To explore the influence of biofilm maturation and timing of exposure on fluoride anticaries efficacy and (2) to explore biofilm recovery post-treatment.

METHODS

Bovine enamel specimens were utilized in a pH cycling model (28 subgroups [n = 18]). Each subgroup received different treatments [exposure]: sodium fluoride [NaF]; stannous fluoride [SnF₂]; amine fluoride [AmF]; and de-ionized water [DIW], at a specific period: early: days 1-4; middle: days 3-6; and late: days 7-10. During non-exposure periods, pH cycling included DIW instead of fluorides. Objective 1: part 1 (cycling for 4, 6, or 10 days). Part 2 (cycling for 10 days). Objective 2: early exposure: three sample collection time points (immediate, 3 days, and 6 days post-treatment); middle exposure: two sample collection time points (immediate, 4 days post-treatment). The enamel and biofilm were analyzed ([surface microhardness; mineral loss; lesion depth]; [lactate dehydrogenase enzyme activity; exopolysaccharide amount; viability]). Data were analyzed using ANOVA (p = 0.05).

RESULTS

Objective 1: Early exposure to fluorides produced protective effects against lesion progression in surface microhardness and mineral loss, but not for lesion depth. Objective 2: Early exposure slowed the demineralization process. SnF₂ and AmF were superior to NaF in reducing LDH and EPS values, regardless of exposure time. They also prevented biofilm recovery.

CONCLUSION

Earlier exposure to SnF₂ and AmF may result in less tolerant biofilm. Early fluoride treatment may produce a protective effect against demineralization. SnF₂ and AmF may be the choice to treat older biofilm and prevent biofilm recovery.

CLINICAL RELEVANCE

The study provides an understanding of biofilm-fluoride interaction with mature biofilm (e.g., hard-to-reach areas, orthodontic patients) and fluoride's sustainable effect hours/days after brushing.

Association of PM2.5 mass and its components with ovarian reserve in a northern peninsular province, China: The critical exposure period and components

BACKGROUND

A possible role of PM2.5 components on ovarian reserve has not been adequately unexplored.

OBJECTIVE

To evaluate the association between PM2.5 components and women' ovarian reserve over critical exposure periods in northern China, where the level of air pollution is among the nation's highest.

METHODS

We included 15,102 women with serum anti-Müllerian hormone (AMH) measurements from the Center for Reproductive Medicine of Shandong University during 2015-2019. Concentrations of PM2.5 and its five major components (0.1° × 0.1°), including sulfate, nitrate, ammonium, organic matter, and black carbon, were assigned to each residential address. Multivariable linear mixed effect models combined with constituent-residual models were performed to estimate the effect sizes of essential components over six short- to long-term exposure periods.

RESULTS

The strength of association was stronger during the process from primary to small antral follicle compared with other longer windows. For every interquartile range increase in PM2.5 mass was associated with - 8.7% (95%CI: -12.3%, -4.9%) change in AMH and the effect size was greatest for sulfate. Women with the lower level of attained education and those living inland were more susceptible compared with other population subgroups.

CONCLUSION

Exposure to specific components of air pollution during critical exposure windows is associated with a decline in ovarian reserve. These data add to the growing body of evidence that environmental factors have adverse effects on reproductive health, particularly for vulnerable population subgroups.

Spatial and temporal evolution and factors influencing soil aggregate stability in the riparian zone during exposure: A case study of the water-level fluctuation zone of the Three Gorges Reservoir, China

The water-level fluctuation zone (WLFZ) is a unique riparian region that forms in response to the operation of the reservoir. The periodic submersion-exposure conditions severely affect the properties of soil and vegetation, thus also change the spatial and temporal development of soil aggregate stability. Nonetheless, the changes in both space and time concerning soil aggregate stability and the factors influencing it during the exposure period in the WLFZ are still unclear. Consequently, the WLFZ within the Three Gorges Reservoir area (TGRA) was taken as the research object, soil and plant samples were obtained from various elevations along the slope at different times to capture the spatial and temporal changes in soil and plant characteristics throughout the exposure period. Moreover, the wet sieving method was utilized to measure the aggregate size distribution and stability of soil aggregates. To further analyze the effects of both individual and mutual variables on the spatial and temporal changes in aggregate stability, methods such as Pearson's correlation analysis, redundancy analysis (RDA), variation partitioning analysis (VPA), and partial least squares path modeling (PLS-PM) were employed. The findings revealed that aggregate stability increased with increasing elevation until peaking and then decreased spatially, whereas the passage of time contributed to enhanced aggregate stability. The spatial variation in aggregate stability was greater than temporal variation. RDA revealed that soil properties (bulk density, soil water content in mass, clay, silt, sand, pH and soil organic matter), environmental factors (elevation, water level, submersion duration and exposure duration) and plant characteristics (shoot and root biomass) contributed 53.6 %, 45.4 % and 0.9 %, respectively, to the spatiotemporal variability in aggregate stability. VPA and PLS-PM analysis further revealed that the main factors controlling the aggregate stability were soil chemical properties. These results provide a basis for further studies on the soil and water conservation in the WLFZ.