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Global marine plastic pollution, which is derived mainly from the input of vast amounts of land-based plastic waste, has drawn increasing public attention. Riverine plastic outflows estimated using models based on the concept of mismanaged plastic waste (MPW) are substantially greater than reported field measurements. Herein, we formulate a robust model using the Human Development Index (HDI) as the main predictor, and the modeled riverine plastic outflows are calibrated and validated by available field data. A strong correlation is achieved between model estimates and field measurements, with a regression coefficient of r 2 = 0.9. The model estimates that the global plastic outflows from 1518 main rivers were in the range of 57,000–265,000 (median: 134,000) MT year–1 in 2018, which were approximately one-tenth of the estimates by MPW-based models. With increased plastic production and human development, the global riverine plastic outflow is projected to peak in 2028 in a modeled trajectory of 2010–2050. The HDI is a better indicator than MPW to estimate global riverine plastic outflows, and plastic pollution can be effectively assessed and contained during human development processes. The much lower global riverine plastic outflows should substantially ease the public’s concern about marine plastic pollution and financial pressure for remediation.

-N′-phenyl-p-phenylenediamine (6PPD) and its quinone derivative, 6PPD-quinone (6PPD-Q), have been found to be prevalent in the environment, but there are currently no data on their presence in humans. Herein, we conducted the first human biomonitoring study of 6PPD and 6PPD-Q by measuring 150 urine samples collected from three different populations (general adults, children, and pregnant women) in South China. Both 6PPD and 6PPD-Q were detected in the urine samples, with detection frequencies between 60% and 100%. Urinary 6PPD-Q concentrations were significantly higher than those of 6PPD and correlated well with those of 6PPD (p < 0.01), indicating coexposure to 6PPD and 6PPD-Q in humans. In vitro metabolic experiments demonstrated rapid depletion of 6PPD by human liver microsomes, which should be responsible for the lower concentrations of 6PPD in human urine. Additionally, pregnant women exhibited apparently higher concentrations of 6PPD and 6PPD-Q (median 0.068 and 2.91 ng/mL, respectively) than did adults (0.018 and 0.40 ng/mL) and children (0.015 and 0.076 ng/mL). The high daily urinary excretion of 6PPD-Q in pregnant women was estimated to be 273 (ng/kg bw)/day. Considering that 6PPD-Q was a lethal toxicant to multiple aquatic species, the potential human health risks posed by its long-term exposure require urgent attention.