Sampling
ORs with similar dimensions and air exchange rates at two different hospitals were selected as the sampling environments. In order to collect detectable ES samples, mastectomy was selected as the target operation because of the longer operation time and noteworthy electrocautery usage. Since the clean room classification is a general guideline of environmental cleanliness and sterility for various ORs in hospitals, ORs with a clean room level of 104 (particle number concentration with particle size greater than 0.5 μm should be less than 104/ft3) were chosen for mastectomy investigation in this study.
For sampling consistency and further comparison between different mastectomies, the electrocautery power was kept at 25 W under the coagulation mode throughout the entire study. Fourteen mastectomies were investigated by collecting ES gas/particle samples. According to the results of 2-hour pretest mastectomy, electrocautery usage time was scrupulously recorded with a laser portable particle counter (Met One, Grants Pass, Oregon, USA) monitoring particle number concentrations of particle 50% cut-sizes from 0.3, 0.5, 1, 3, 5, and 10 μm at an interval of 5 minutes until the end of surgery.
For the purpose of investigating surgical staff exposure to ES, air samples were taken within 30 cm at the breathing height of the surgeons and the anesthetic technologist (AT) without contacting the sterile region. Air samples, including particle and gaseous phases, were collected at the sampling flow rate of 30 L/min. The ES air was first passed through a 47-mm quartz fiber filter to collect smoke aerosols, and then polluted gases were trapped by the polyurethane foam of PUF-XAD-PUF adsorbent. Before surgical operation, background air samples were also collected for comparison. This study was approved by the Institutional Review Board and Ethics Committee in our hospital. Informed consent was obtained from all patients.
PAH analysis
The PAH chemical analysis protocol included soxhlet and sonication extraction, solvent exchange, cleanup, nitrogen blow down, and the final gas chromatography/mass spectrometry (GC/MS) analysis. Prior to sample solvent extraction, samples for PAHs were spiked with a deuterium surrogate solution containing 10 ng of d8-naphthalene, d10-fluorene, d12-chrysene, and d12-perylene to monitor efficiency throughout the entire analytical process. A sonication method was modified to extract particle-bound PAHs from quartz fiber filter samples, while PUF-XAD-PUF adsorbent samples were soxhlet-extracted for 24 hours. This was followed by a solvent exchange to hexane, cleanup with 5% water deactivated silica gel, and nitrogen blow down to about 100 μL. Before GC/MS, a deuterium internal standard solution (10 ng) consisting of d10-phenanthrene, d10-pyrene, and d12-BaP was injected to analyze PAHs both qualitatively and quantitatively.
A Hewlett-Packard gas chromatography (GC, Model 6890) equipped with a mass selective detector (MS, Hewlett-Packard Model 5973) was used to quantify PAHs. The GC/MS was tuned weekly with 1 ng/μL decafluorotriphenylphosphine. A 30 m × 0.25 mm identity column of 0.25-μm film thickness DB-5MS phase (J&W Scientific, Folsom, CA, USA) was used to separate PAHs. A splitless injection system was used, with a 2-minute delay before purge. Helium was the carrier gas, operated at a constant linear velocity of 25 cm/second. The injector and transfer line were maintained at 290°C and 300°C, respectively. The GC temperature program was 50°C for one minute, 20°C/minute to 300°C, and maintained for 15 minutes; the sample injection volume was 1 μL. Selective ion monitoring in the GC/MS was used to quantify individual PAHs.
The PAHs analyzed in this study included naphthalene, acenaphthylene, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, BaP, indeno[c,d]pyrene, dibenzo[a,h]anthracene, and benzo[g,h,i] perylene. In addition, hetero-PAHs, including oxygen, sulfur, and nitrogen, were also detected: 2,3 benzofuran, dibenzofuran, dibenzothiophene, 7,8 benzoquinolene, and carbazole.
In order to positively identify trace level PAHs, a final sample volume of approximately 100 μL and GC/MS detection limits of approximately 3 to 25 pg of individual PAHs per injection were achieved. The significance of PAH concentration above the method detection limit was checked by evaluating field and laboratory blanks, and spiked PAH recovery. The method detection limit was determined as three times the standard deviation above the mean in the field blanks.