Assessing human exposure risk and lung disease burden posed by airborne silver nanoparticles emitted by consumer spray products

Figures & data

Figure 1 Schematic showing the overall study framework.

Notes: (A) Problem formulation of human health risk or lung burdens posed by exposures of airborne AgNPs emitted from spray products, (B) exposure analysis of mass concentrations and particle size distributions of aerosolized AgNPs, (C) effect analysis of relationship between BALF neutrophil number and AgNPs dose in human lung, (D) threshold estimation of AgNPs lung burdens, and (E) risk characterization of airborne AgNPs toxicities in human lung.

Abbreviation: BALF, bronchoaveolar lavage fluid.

Table 1 Equations for compartmentalized PBAD model along with used values of rate parameters

Interpretation	Equationsa
Mass-based dosimetric exposure model	D = C × DF × ED × BR	(T1)
Silver deposition fraction in alveolar–interstitial region	$\text{DF=}\left(\frac{0.0155}{{\mathrm{d}}_{\mathrm{P}}}\right)\left[\exp \left(-0.416{(\ln {\mathrm{d}}_{\mathrm{P}}+2.84)}^2\right)+19.11\exp \left(-0.482{(\ln {\mathrm{d}}_{\mathrm{P}}-1.362)}^2\right)\right]$	(T2)
AgNPs dose (mg) in alveolar region A: X1	$\frac{{\text{dX}}_1(\mathrm{t})}{\text{dt}}=\mathrm{D}-{\mathrm{k}}_{\mathrm{P}}{\mathrm{X}}_1(\mathrm{t})-{\mathrm{k}}_{\mathrm{i}}{\mathrm{X}}_1(\mathrm{t})+{\mathrm{k}}_{\mathrm{a}}{\mathrm{X}}_2(\mathrm{t})$	(T3)
AgNPs dose in alveolar macrophage region M: X2	$\frac{{\text{dX}}_2(\mathrm{t})}{\text{dt}}={\mathrm{k}}_{\mathrm{P}}{\mathrm{X}}_1(\mathrm{t})-{\mathrm{k}}_{\mathrm{c}}{\mathrm{X}}_2(\mathrm{t})-{\mathrm{k}}_{\mathrm{a}}{\mathrm{X}}_2(\mathrm{t})$	(T4)
AgNPs dose in interstitial region I: X3	$\frac{{\text{dX}}_3(\mathrm{t})}{\text{dt}}={\mathrm{k}}_{\mathrm{i}}{\mathrm{X}}_1(\mathrm{t})-{\mathrm{k}}_1{\mathrm{X}}_3(\mathrm{t})$	(T5)
Total AgNPs deposition, X	$\mathrm{X}(\mathrm{t})={\mathrm{X}}_1(\mathrm{t})+{\mathrm{X}}_2(\mathrm{t})+{\mathrm{X}}_3(\mathrm{t})$	(T6)
AgNPs dose in lymph node region L: X4	$\frac{{\text{dX}}_4(\mathrm{t})}{\text{dt}}={\mathrm{k}}_1{\mathrm{X}}_3(\mathrm{t})$	(T7)
Rate parameter	Value (day^−1)
kp	0.996 (0–0.996)a,b
kc	1.50×10^−3 (1.10×10^−4 –4.40×10^−3)a,c
ka	3.30×10^−2b
ki	0.42943 (0.42939–0.42946)a,d
kl	3.75×10^−3 (2.74×10^−3 –3.90×10^−3)a,d

a Notes: Min–max.

b Data from Tran et al.¹⁸

c Data from Kuempel et al.¹⁶

d Data from Takenaka et al.⁴²

Abbreviations: PBAD, physiologically based alveolar deposition; A, alveolar region; BR, breathing rate; DF, AgNPs deposition fraction in alveolar-interstitial region; ED, exposure duration; I, interstitial region; L, lymph node region; M, alveolar macrophage region; k_a, apoptosis rate of macrophage; k_c, physical clearance rate of nanoparticle; k_i, transferred rate of AgNPs from alveolar region to interstitial region; k_l, transferred rate of AgNPs from interstitial region to lymph node; k_p, phagocytosis rate of macrophage; C, mass concentration of AgNPs aerosols (μg m⁻³); AgNP, silver nanoparticle.

Figure 2 Schematic showing the compartmentalized PBAD model.

Abbreviations: PBAD, physiologically based alveolar deposition; A, alveolar region; M, alveolar macrophage region; I, interstitial region; L, lymph node region; X₁, AgNPs in alveolar region; X₂, AgNPs in alveolar macrophage; X₃, AgNPs in interstitial region; X₄, AgNPs in lymph node region; k_i, transfer rate of AgNPs from alveolar region to interstitial region; k_l, transferred rate of AgNPs from interstitial region to lymph node; k_p, phagocytosis rate of macrophage; k_a, apoptosis rate of macrophage; k_c, physical clearance rate of AgNPs; AgNP, silver nanoparticle.

Figure 3 Estimated mass concentrations of aerosols based on size distributions of droplets in spray (A, B) DI, (C, D) DO_S, and (E, F) DO_L in non-intensive or intensive application.

Abbreviations: DI, disinfectant; DO_S, deodorant of AgNPs in smaller scales; DO_L, deodorant of AgNPs in larger scales; LN, lognormal; AUC, area under the curve; AgNP, silver nanoparticle.

Figure 4 (A, B) Total AgNP lung burden and (C, D) accumulation rates after long-term exposure of aerosolized AgNPs released by AgNP-containing spray products in non-intensive and intensive using condition.

Abbreviations: AgNP, silver nanoparticle; DO_S, deodorant of AgNPs in smaller scales; DO_L, deodorant of AgNPs in larger scales; DI, disinfectant.

Figure 5 Dose–response describing relationship between lung burdens of (A) 34 nm and (B) 60 nm AgNPs and increase of neutrophils in BALF-based on the Hill model.

Abbreviations: AgNP, silver nanoparticle; BALF, bronchoalveolar lavage fluid.

Figure 6 (A) Box and whisker plots of HQs in the criteria of γ₁-based threshold for the elevation of neutrophils in BALF. (B) Probability distribution of HQ exposed to spray DO_S in intensive application, and ERs for HQ of using (C, D) DO_S and (E, F) DO_L in non-intensive or intensive applications.

Abbreviations: HQ, hazard quotients; γ₁, threshold dose preventing from causing 1% maximum effects on neutrophil elevations; DO_S, deodorant of AgNPs in smaller scales; DO_L, deodorant of AgNPs in larger scales; BALF, bronchoalveolar lavage fluid; ER, exceedance risk; AgNP, silver nanoparticle.

Figure 7 Sensitivity analysis for physiological parameters used in the PBAD model against total AgNP accumulation in human lung (μg) posed by aerosolized AgNP spray products.

Abbreviations: AgNP, silver nanoparticle; PBAD, physiologically based alveolar deposition; k_i, transfer rate of AgNPs from alveolar region to interstitial region; k_l, transfer rate of AgNPs from interstitial region to lymph node; k_p, phagocytosis rate of macrophage; k_a, apoptosis rate of macrophage; k_c, physical clearance rate of nanoparticle.

Figure 8 A conceptual model showing mechanisms of inflammation response exposed to aerosolized AgNPs via inhalation.

Abbreviations: AgNP, silver nanoparticle; PBAD, physiologically based alveolar deposition.

TranCLGrahamMBuchananDA Biomathematical Model for Rodent and Human Lung Describing Exposure, Dose, and Response to Inhaled SilicaEdinburgh, UKInstitute of Occupational Medicine2001

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KuempelEDO’FlahertyEJStaynerLTA biomathematical model of particle clearance and retention in the lungs of coal minersRegul Toxicol Pharmacol2001341698711502158

 PubMed Web of Science ®Google Scholar

TakenakaSKargERothCPulmonary and systemic distribution of inhaled ultrafine silver particles in ratsEnviron Health Perspect2001109Suppl 4547

 PubMed Web of Science ®Google Scholar