Identification of micro- and nanoplastic particles in postnatal sprague-dawley rat offspring after maternal inhalation exposure throughout gestation

Abstract

Micro-nanoplastic particulates (MNPs) have been identified in both indoor and outdoor environments. From these real-world exposures, MNPs have been identified in human fluids and organ tissues, including the placenta and breastmilk. Laboratory studies have identified MNPs are capable of crossing the placental barrier and depositing in fetal tissues; however, it remained unclear if MNPs persist in offspring tissues after birth. Six pregnant Sprague-Dawley rats were divided equally into two groups: control and exposed to polyamide-12 (PA-12) MNP aerosols (11.46 ± 3.78 mg/m³) over an average of 4.35 h ± 0.39 for 10 non-consecutive days between gestational day (GD) 6 - GD 19, in our custom rodent exposure chamber, allowing for whole-body inhalation. Two-weeks after delivery in-house, offspring tissues (i.e. lung, liver, kidney, heart, brain) from 1 male and 1 female pup per litter were fixed in 4 % paraformaldehyde, sectioned, stained with hematoxylin and eosin, and assessed using hyperspectral dark-field microscopy. PA-12 MNPs were identified in all offspring tissues of the exposed dams. No MNPs were visualized in control tissues. These findings have important implications for human MNPs translocation, deposition, maternal/fetal health, and the developmental origins of health and disease. Further research is warranted to quantify MNPs mass deposition, biological accumulation, and systemic toxicity.

Keywords: Deposition; Inhalation; Maternal-fetal; Microplastic; Nanoplastic; Offspring; Particle; Polyamide; Translocation.

Figure 1:

Real-time size characterization of aerosolized polyamide powder identifies the presence of micro- and nano-scale particles as characterized by electrical mobility (A; SMPS) and aerodynamic diameter (B; ELPI). SMPS data (A) are presented as geometric mean ± SEM for the animal exposures. HR-ELPI data (B) is presented as representative data acquired on March 16, 2023.

Figure 2:

Hyperspectral dark-field microscopy images of the offspring lung tissues for control male (A) and female (B) pups. Polyamide MNPs (white arrows) in the male (C) and female (D) offspring. Panels (E) and (F) apply the spectral EDHF SLF overlay to the male and female tissues, respectively. The wavelength spectra is presented in panel (G). No polyamide MNPs were identified in any (male or female) control pups. n=6 (3 male/3 female) offspring representing 3 litters in each group.

Figure 3:

Hyperspectral dark-field microscopy images of the offspring heart tissues for control male (A) and female (B) pups. Polyamide MNPs (white arrows) in the male (C) and female (D) offspring. Panels (E) and (F) apply the spectral EDHF SLF overlay to the male and female tissues, respectively. The wavelength spectra is presented in panel (G). No polyamide MNPs were identified in any (male or female) control pups. n=6 (3 male/3 female) offspring representing 3 litters in each group.

Figure 4:

Hyperspectral dark-field microscopy images of the offspring liver tissues for control male (A) and female (B) pups. Polyamide MNPs (white arrows) in the male (C) and female (D) offspring. Panels (E) and (F) apply the spectral EDHF SLF overlay to the male and female tissues, respectively. The wavelength spectra is presented in panel (G). No polyamide MNPs were identified in any (male or female) control pups. n=6 (3 male/3 female) offspring representing 3 litters in each group.

Figure 5:

Hyperspectral dark-field microscopy images of the offspring kidney tissues for control male (A) and female (B) pups. Polyamide MNPs (white arrows) in the male (C) and female (D) offspring. Panels (E) and (F) apply the spectral EDHF SLF overlay to the male and female tissues, respectively. The wavelength spectra is presented in panel (G). No polyamide MNPs were identified in any (male or female) control pups. n=6 (3 male/3 female) offspring representing 3 litters in each group.

Figure 6:

Hyperspectral dark-field microscopy images of the offspring brain tissues for control male (A) and female (B) pups. Polyamide MNPs (white arrows) in the male (C) and female (D) offspring. Panels (E) and (F) apply the spectral EDHF SLF overlay to the male and female tissues, respectively. The wavelength spectra is presented in panel (G). No polyamide MNPs were identified in any (male or female) control pups. n=6 (3 male/3 female) offspring representing 3 litters in each group.