Blood uptake and urine excretion of nano- and micro-plastics after a single exposure.

Nano- and micro-plastic (NMP) pollution has emerged as a global issue; however, uptake in the blood is controversial. Also, there is no evidence that NMPs are excreted via urine. This study was designed to clarify the time course of NMPs absorption in blood and the excretion in urine. Male mice received a single administration of fluorescent polystyrene (PS) beads (100-nm and 3-µm) via tail vein injection, gavage, or pulmonary perfusion. Blood and urine samples were measured 0.5, 1, 2, and 4 h after exposure by confocal laser scanning microscope (CLSM). Transmission electron microscopy (TEM) was performed to corroborate the findings. Fluorescence particles were detected in both blood and urine from the 100-nm and 3-µm PS-treated groups after exposure. In the 3-µm PS treated group, particles with corresponding diameters were detected after intravenous injection and pulmonary perfusion, and particles with a diameter <3 µm were detected in blood samples after gavage. The fluorescent signal in urine was particularly weak and the size was <3 µm. Significant time course changes in fluorescence intensity were demonstrated in blood and urine (P < 0.05) after intravenous injection and pulmonary perfusion in the 100-nm PS-treated group. By contrast, significant changes were detected in the urine (P < 0.05), but not the blood, after gavage. TEM confirmed the presence of particles with corresponding diameters in blood samples; however, the excretion in urine was difficult to confirm for nano-plastics (NPs) and micro-plastics (MPs) because all particles with diameters of approximately 100 nm and 3 µm had irregular shapes and no clear boundaries. Our findings revealed that both NPs and MPs enter the blood circulation through digestive and respiratory pathways. Both 100-nm and 3-µm NMPs may be excreted through urine, but further evidence is needed. The physical and chemical properties of MPs may be impacted by digestive processes in vivo.

Association of Obesity with Onset of Puberty and Sex Hormones in Chinese Girls: A 4-Year Longitudinal Study.

OBJECTIVE: To examine the influence of childhood obesity on the early onset of puberty and sex hormones in girls. METHODS: Healthy girls with different percentages of body fat at baseline (40 obese, 40 normal, and 40 lean) were recruited from three elementary schools in Shenyang, China. These girls (mean age 8.5 years) were also matched by height, school grade, Tanner stage, and family economic status at baseline. Anthropometry, puberty characteristics, and sex hormone concentrations were measured at baseline and at each follow-up visit. The generalized estimating equation model and analysis of variance for repeated measures using a generalized linear model were used to determine the differences in puberty characteristics and sex hormones among three groups. RESULTS: Over 4 years, mean age of breast II onset was earlier among obese girls (8.8 years) than normal girls (9.2 years) and lean girls (9.3 years). The prevalence (%) of early-maturation in the obese, normal, and lean groups was 25.9%, 11.1%, and 7.4%, respectively. Obesity was associated with an increased risk for breast stage II (year 2: RR, 6.3; 95% CI, 1.9-21.1 and year 3: RR, 6.9; 95% CI, 0.8-60.1). None of the girls experienced menarche in the first year; however, by the fourth year 50.0% of obese girls had menarche onset, which was higher than normal weight (27.5%) and lean girls (8.1%). The mean estradiol level increased with age in the obese, normal, and lean groups. The mean estradiol concentration was higher in obese girls than in normal and lean girls throughout the 4-year period (P<0.05). CONCLUSIONS: Childhood obesity contributes to early onset of puberty and elevated levels of estradiol in girls.

Sexual development in prepubertal obese boys: a 4-year longitudinal study.

The objective of the study was to evaluate whether or not sexual development differs between boys with prepubertal obesity and boys of normal weight. We enrolled healthy obese and normoweight schoolboys from Shenyang City, Liaoning, China. Eligible boys were at Tanner stage 1 and 8 years of age at baseline. We measured testosterone and estradiol concentrations in the saliva and assessed auxology annually for 4 years. In all 56 obese and 56 normoweight boys, the height, weight, body composition, and sex organ volume increased with age. The percentages of body fat, fat mass, and lean mass were all higher in obese than in normoweight boys. The mean testicular volume was smaller in obese boys than in normoweight boys. The sex hormone concentrations increased with age, except for testosterone in obese boys in year 3 of follow-up. In year 4, estradiol concentrations were significantly higher in obese boys than in normoweight boys. Excessive adiposity in prepubertal boys might affect testicular volume, possibly because of high estradiol and low testosterone concentrations.