# Neutralization of ricin toxin on building interior surfaces using liquid decontaminants

## TL;DR

This study tested how well common cleaning products can neutralize ricin toxin on building materials, finding that peracetic acid and bleach were most effective.

## Contribution

The study provides empirical data on the decontamination efficacy of COTS cleaners against ricin on various substrates.

## Key findings

- Decontamination efficacy varied by decontaminant and substrate material.
- 0.45% peracetic acid and 20,000-ppm sodium hypochlorite showed the best results.
- 0.45% peracetic acid achieved 97.8 to 99.8% toxin reduction with 30-min contact time.

## Abstract

Ricin is a highly toxic protein, capable of inhibiting protein synthesis within cells, and is produced from the beans of the Ricinus communis (castor bean) plant. Numerous recent incidents involving ricin have occurred, many in the form of mailed letters resulting in both building and mail sorting facility contamination. The goal of this study was to assess the decontamination efficacy of several commercial off-the-shelf (COTS) cleaners and decontaminants (solutions of sodium hypochlorite [bleach], quaternary ammonium, sodium percarbonate, peracetic acid, and hydrogen peroxide) against a crude preparation of ricin toxin. The ricin was inoculated onto four common building materials (pine wood, drywall joint tape, countertop laminate, and industrial carpet), and the decontaminants were applied to the test coupons using a handheld sprayer. Decontamination efficacy was quantified using an in-vitro cytotoxicity assay to measure the quantity of bioactive ricin toxin extracted from test coupons as compared to the corresponding positive controls (not sprayed with decontaminant). Results showed that decontamination efficacy varied by decontaminant and substrate material, and that efficacy generally improved as the number of spray applications or contact time increased. The solutions of 0.45% peracetic acid and the 20,000-parts per million (ppm) sodium hypochlorite provided the overall best decontamination efficacy. The 0.45% peracetic acid solution achieved 97.8 to 99.8% reduction with a 30-min contact time.