An approach to quantify ortho-phthalaldehyde contamination on work surfaces.

Ortho-phthalaldehyde (OPA) is used as a high-level disinfectant for reusable medical devices in healthcare settings. The ACGIH recently adopted a Threshold Limit Value-Surface Limit (TLV-SL; 25 µg/100 cm2) for OPA surface contamination to prevent induction of dermal and respiratory sensitization following dermal exposure. However, there is no current validated method to measure OPA surface contamination. This study aimed to develop a standardized approach for sample collection and quantitative determination of OPA from work surfaces for use in risk assessment practices. The reported method utilises readily available commercial wipes to collect surface samples coupled with direct detection of OPA via liquid chromatography time of flight mass spectrometry (LC-ToF-MS). This approach avoided complex derivatization steps commonly required for the analysis of aldehydes. Method evaluation was conducted in accordance with the Occupational Safety and Health Administration (OSHA) surface sampling guidelines. Overall recoveries of 25 µg/100 cm2 of OPA from stainless steel and glass surfaces were 70% and 72%, respectively. The reported LOD for this method was 1.1 µg/sample and the LOQ was 3.7 µg/sample. OPA remained stable on the sampling medium for up to 10 days, when stored at 4 °C. The method was demonstrated in a workplace surface assessment at a local hospital sterilising unit, successfully detecting OPA on work surfaces. This method is intended to supplement airborne exposure assessment and provide a quantitative assessment tool for potential dermal exposure. When used in conjunction with a thorough occupational hygiene program that includes hazard communication, engineering controls, and personal protective equipment, skin exposure and consequent sensitization risks in the workplace can be minimized.

Rhizoremediation of hydrocarbon contaminated soil using Australian native grasses.

Rhizoremediation involves the breakdown of contaminants in soil resulting from microbial activity that is enhanced in the plant root zone. The objective of this study was to assess Australian native grasses for their ability to stimulate removal of aliphatic hydrocarbons from a mine site soil. Time-course pot experiments were conducted in a greenhouse with three grass species (Cymbopogon ambiguus, Brachiaria decumbens, and Microlaena stipoides) in a mine site soil experimentally contaminated with a 60:40 diesel:oil mixture at 1% (w/w) concentration. Plants were cultivated for 100days with periodic evaluation of changes in soil total petroleum hydrocarbon (TPH) concentration, soil lipase activity, and abundance of hydrocarbon-degrading microorganisms. Results were compared to unplanted control treatments. Significantly lower endpoint TPH concentrations were recorded in planted soil compared to unplanted soil (p=0.01). Final TPH concentrations and rates of TPH removal varied between grass species, with total TPH removal of between 50% and 88% achieved in planted treatments. The presence of grasses significantly increased the abundance of hydrocarbon-degrading microorganisms and soil lipase activity relative to unplanted soil (p<0.05). Residual TPH concentration was found to be closely (negatively) correlated with abundance of hydrocarbon-degrading microorganisms and to a lesser extent with soil lipase activity. Australian native grass species were identified that effectively enhance the remediation of diesel/oil contaminated soil, without any requirement for nutrient supplementation. Results may have extensive application to the nationwide problems associated with hydrocarbon contaminated sites.