Takashi Amagai

Organophosphorus compounds, widely used as flame retardants and plasticizers in plastic products, present significant health risks due to their potential adverse effects. While inhalation and ingestion are well-studied exposure pathways, dermal exposure remains underexplored. In recent years, the growing popularity of gamingdriven by extended home stays during the COVID-19 pandemic and the inclusion of e-sports in international competitionshas led to prolonged contact with gaming devices, particularly among young people and professional gamers. This study investigates dermal exposure to triphenyl phosphate (TPhP) from 37 home-use video game controllers. TPhP was detected in 5 first-party and 22 third-party controllers, with concentrations reaching up to 530 μg g^–1. Using artificial skin (EPISKIN), we measured a TPhP skin permeation rate of 0.42 ng cm^–2 h^–1. Monte Carlo simulations were used to estimate daily dermal intake rates; professional gamers (5th percentile–50th percentile–95th percentile, 9.0–22–45 ng kg^–1 day^–1) and e-sports students (5.3–8.5–18 ng kg^–1 day^–1) were identified as the most exposed groups due to prolonged gaming sessions. Remarkably, dermal exposure from the controller was found to rival or exceed other pathways, including dust ingestion and inhalation. This study highlights the urgent need for strategies to mitigate dermal exposure risks from gaming devices.

As an alternative to cigarettes, the sales of heated tobacco products (HTPs) have increased in the Japanese market. This may contribute to improving a smoker's health because the levels of most toxic compounds─such as tobacco-specific nitrosamines (TSNAs) and volatile organic compounds (VOCs)─in the mainstream of HTPs are lower than those in cigarettes. However, the risks associated with the flavors that provide attractive tastes to HTPs remain unknown. We demonstrated that compared with cigarettes, HTPs reduce the health risks associated with VOCs and TSNAs while achieving comparable nicotine and flavor levels. The VOC and TSNA concentrations in the mainstream aerosol of HTPs were 0.0039 (benzene)-0.53 (acetaldehyde) times lower than those in cigarettes. Using HTPs may still pose adverse noncarcinogenic and carcinogenic effects on human health, as indicated by hazard quotients >1 for acrolein and acetaldehyde, margins of exposure 1.0 × 10^-6 for acetaldehyde. Additionally, the exhalation of mainstream aerosol may increase the indoor acrolein concentration to 0.069 μg m^-3, exceeding the reference concentration for acrolein (0.02 μg m^-3). Therefore, reducing acrolein concentrations is an effective measure for improving the safety of HTP use.

Alternative flame retardants, especially those containing phosphorus, have changed over time to meet flammability standards; however, studies on the presence of these alternatives on indoor dust, which is a major exposure carrier to human beings, have been limited. In this study, we measured the concentrations of four novel phosphorus flame retardants (PFRs), including 6‐benzylbenzo[ c ][2,1]benzoxaphosphinine 6‐oxide (BzlDOPO), naphthalen‐2‐yl diphenyl phosphate (NDPhP), (5‐ethyl‐2‐methyl‐2‐oxido‐1,3,2‐dioxaphosphorinan‐5‐yl)methyl methyl methylphosphonate (PMMMP), and bis[(5‐ethyl‐2‐methyl‐2‐oxido‐1,3,2‐dioxaphosphinan‐5‐yl)methyl] methylphosphonate (di‐PMMMP), and 13 conventional PFRs on indoor dust collected from 29 dwellings and a kindergarten in Japan. The concentration of the PFRs on indoor dust ranged from 3.0 ng g ⁻¹ (TPP [tripropyl phosphate]) to 4,600,000 ng g ⁻¹ (TBOEP [tris (2‐butoxyethyl) phosphate]). Among the PFRs targeted in this study, TBOEP exhibited the highest median concentration, followed by tris(2‐chloroisopropyl) phosphate (TCPP), tris(2‐chloroethyl) phosphate (TCEP) and triphenyl phosphate (TPhP), and tris(1,3‐dichloro‐2‐propyl) phosphate (TDCPP). The novel PFRs, PMMMP, di‐PMMMP, BzlDOPO, and NDPhP, were detected at 51, 63, 6, and 3 ng g ⁻¹ , respectively, in dust samples. TBOEP exhibited the lowest margin of exposure (1.5 × 10 ³ [5%ile]) among the PFRs examined. The results indicate that the novel PFRs are present in indoor environments and that humans are exposed through indoor dust. Further studies are needed to evaluate the toxicity of novel PFRs and assess their potential health risks.