Activated carbon adsorption sheets suppress volatilization of anticancer drugs excreted in urine,preventing environmental contamination and human exposure

Abstract

Background

Anticancer drugs excreted in urine can disperse during urination, contaminating toilets and causing secondary exposure. Activated carbon sheets adsorb urinary drugs and limit surface diffusion, but whether adsorbed drugs subsequently vaporize is unknown. We evaluated vaporization of cyclophosphamide (CPA) applied to activated carbon sheets.

Methods

CPA (10 mg/2 mL) was placed on 100-cm² activated carbon sheets or control sheets without activated carbon and incubated for 24 h in a 4-L chamber at 37 °C. Vaporization was assessed by Ames test (reverse-mutated Salmonella colony counts). CPA in chamber gas and wipe samples from the inner surfaces of the chamber was quantified by HPLC–MS/MS. Sheets were tested immediately after CPA application, after drying, and after rewetting (immediately and at 3 and 7 days after contamination).

Results

Compared with no-CPA exposure, colony counts increased significantly after exposure to CPA-dropped control sheets (p < 0.001), whereas no increase occurred with CPA-coated activated carbon sheets. Gas analysis detected no CPA above the quantification limit when applied to activated carbon sheets; a small amount (49 ng) appeared in one control sample. Wipe samples contained far less CPA on activated carbon than on control sheets (79–93% reduction), and these differences persisted through day 7.

Conclusions

Across bioassay and instrumental analyses, activated carbon sheets retained adsorbed CPA without measurable vaporization for at least 7 days. Activated carbon sheets may offer a practical measure to reduce urine-derived antineoplastic contamination and inhalational exposure from vaporization in toilet environments.