Polychlorinated biphenyl (PCB) half-lives in humans: A systematic review.

This manuscript presents a systematic review of PCB half-lives reported in the scientific literature. The review was completed in accordance with PRISMA guidelines and included a review of almost 1000 peer-reviewed publications. In total, 26 articles were found to report half-lives in humans, with the majority of data coming from studies performed in North America on individuals suspected to have been exposed to PCBs. Terminology for reporting PCB half-lives was inconsistent, so we have attempted to consolidate this and recommend using either "apparent half-life" or "intrinsic half-life" in future studies. Within the literature, values for reported half-lives varied considerably for different PCBs. Less chlorinated PCBs generally have shorter half-lives than more chlorinated PCBs. It was interesting to note the large variability of half-lives reported for the same PCB. For example, the reported half-life for PCB 180 varied by nearly 3 orders of magnitude (0.34 years-300 years). Our review identified that the half-lives estimated were largely dependent on the studied cohort. We discuss the importance of PCB body burden, degree of chlorination and PCB structure, gender, age, breastfeeding, BMI, and smoking status on half-life estimations. We also identified significantly shorter half-lives for some PCBs in occupationally exposed individuals compared to results reported from the general population. PCB half-lives are not the same for every PCB or every individual. Therefore, careful consideration is needed when these values are used in human exposure studies.

Occupational risk of organophosphates and other chemical and radiative exposure in the aircraft cabin: A systematic review.

Occupational exposure to oil fumes, organophosphates, halogenated flame retardants, and other volatile and semi-volatile contaminants is a concern within the aviation industry. There is no current consensus on the risk attributed to exposure to these chemical classes within the aircraft cabin. Contaminant concentrations rarely exceed conventional air quality guidelines, but concerns have been raised about these guidelines' applicability within the aircraft environment. This systematic review, the largest and most comprehensive completed to date on the subject matter, aims to synthesize the existing research related to chemical and other exposures inside the aircraft cabin to determine the occupational risk that may be attributed said exposure, as well as, determine knowledge gaps in source, pathway, and receptor that may exist. The Science Direct, Scopus, and Web of Science databases were queried with five search terms generating 138 manuscripts that met acceptance criteria and screening. Several potential areas requiring future examination were identified: Potable water on aircraft should be examined as a potential source of pollutant exposure, as should air conditioning expansion turbines. Historical exposure should also be more fully explored, and non-targeted analysis could provide valuable information to comprehend the aircraft cabin exposome. Occupational risk under typical flight scenarios appears to be limited for most healthy individuals. Contaminants of concern were demonstrated to be extant within the cabin, however the concentrations under normal circumstances do not appear to be individually responsible for the symptomologies that are present in impacted individuals. Questions remain regarding those that are more vulnerable or susceptible to exposure. Additionally, establishing the effects of chronic low dose exposure and exposure to contaminant mixtures has not been satisfied. The risk of acute exposure in mitigable fume events is substantial, and technological solutions or the replacement of compounds of concern for safer alternatives should be a priority.

A comparison of the effectiveness of QuEChERS, FaPEx and a modified QuEChERS method on the determination of organochlorine pesticides in ginseng.

This study provides a review of methods used in the determination of organochlorine pesticides (OCPs) in ginseng and compares the effectiveness of three extraction methods (Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), a modified QuEChERS and a Fast Pesticide Extraction (FaPEx)) in the analyses of 20 OCPs in ginseng root samples. For each method, sample mass, solvent volume and sorbent mass were varied to identify the optimum combination to effectively isolate analytes of interest from the complex sample matrix. Extracts were analyzed using the gas chromatography-µ-electron capture detector (GC-µ-ECD), and confirmatory analyses performed by gas chromatography-tandem-mass spectrometry (GC-MS/MS). Eighteen out of 20 OCPs spiked onto in-house prepared ginseng samples produced acceptable recoveries (51-156%) when extracted using QuEChERS and FaPEx. All 20 analytes, including dichlorodiphenyldichloroethane (p, p'- DDD) and dichlorodiphenyltrichloroethane (o, p'-DDT), produced acceptable recoveries (51-129%) with the use of a modified QuEChERS method. The applicability of the modified QuEChERS method was demonstrated through the analysis of ginseng samples grown in endosulfan-treated soil. The samples were analyzed by both GC-µ-ECD and GC-MS/MS with no significant difference identified in the results of each analytical method. This study highlights the applicability of the modified QuEChERS method, in combination with GC- µ-ECD, to determine organochlorine pesticides in ginseng. This may be especially useful for laboratories in developing countries and less advanced institutions without access to MS/MS instrumentation.

Determination of Halogenated Flame Retardants Using Gas Chromatography with Atmospheric Pressure Chemical Ionization (APCI) and a High-Resolution Quadrupole Time-of-Flight Mass Spectrometer (HRqTOFMS).

A method to determine halogenated flame retardants was developed that utilizes gas chromatography with atmospheric chemical ionization (APCI) high-resolution quadrupole time-of-flight mass spectrometry (HRqTOFMS). The new GC-APCI-HRqTOFMS method was used to determine the presence of 65 halogenated flame retardants (HFRs) in the United Sates National Institute of Standards and Technology (NIST) organic contaminants in house dust standard reference material (SRM). The accuracy of the measurements was compared to the certified NIST value for polybrominated diphenyl ethers (PBDEs) and had an average accuracy for the 14 certified PBDEs of 109% with subpicogram detection limits (on column) from a single 1 µL injection with a run time of 18 min. SRM2585 extracts were also analyzed by GC electron ionization (EI) high-resolution mass spectrometry (HRMS), and there was an excellent correlation between the two data sets (R2 value of 0.996). The presence of 25 additional HFRs were also screened in the dust standard, and 10 were detected in concentrations above the limits of detection; these were p-TBX, PBBZ, PBT, PBEB, TDCPP, HBBZ, EHTBB, TBBPA, BEHTBP, and BTBPE. The results presented show that the proposed APCI-HRqTOFMS method was comparable and in many cases an improvement on the existing EI-HRMS method.

A comparison of fresh and used aircraft oil for the identification of toxic substances linked to aerotoxic syndrome.

Fresh and used aircraft engine lubricants (Mobil Jet Oil II) were analysed using a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICRMS) and comprehensive two dimensional gas chromatography with high resolution time of flight mass spectrometry (GCxGC-HRTOFMS). The composition of the fresh oil was established, with special focus to its tricresyl phosphate (TCP) content as this has formed the focus for most investigations into aerotoxic syndrome. The results showed that only four TCP isomers were present at detectable levels in the fresh oil: mmm-TCP, mmp-TCP, ppm-TCP and ppp-TCP. The results indicate that the formulation of Mobile Jet Oil II does not contain the more toxic ortho substituted TCP isomers at concentrations above 0.0005%. The temperatures of jet engines during operation are greater than 200 °C which creates the potential to alter the composition of the original oil and create other toxic compounds. The results show there may be a significant risk from alkylated cresyl phosphates, which were identified in the used oils at concentrations calculated in the range of 0.13-0.69%. w/w. Several xylenyl and ethylphenyl phosphates have been shown to exhibit a similar toxicity to ortho substituted TCP isomers which makes there discovery in used oil significant. These compounds should be included in future aircraft air quality studies and when assessing the risks and causes of aerotoxic syndrome.

Can polychlorinated biphenyl (PCB) signatures and enantiomer fractions be used for source identification and to age date occupational exposure?

Detailed polychlorinated biphenyl (PCB) signatures and chiral Enantiomer Fractions (EFs) of CB-95, CB-136 and CB-149 were measured for 30 workers at a transformer dismantling plant. This was undertaken to identify sources of exposure and investigate changes to the PCB signature and EFs over different exposure periods. Approximately 1.5 g of serum was extracted and PCB signatures were created through analysis by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) and EFs calculated following analysis by gas chromatography with high resolution mass spectrometry (GC-HRMS). A total of 84 PCBs were identified in the serum samples with concentrations of the 7 indicator PCBs ranging from 11-350 ng g(-1) of serum (1.2-39 µg g(-1) lipid). The PCB signatures were interpreted using principal component analysis (PCA) which was able to distinguish workers with background or recent minimal exposure from those with prolonged occupational exposure. Occupationally exposed individuals had a similar PCB profile to Aroclor A1260. However, individuals with prolonged exposure had depleted proportions of several PCB congeners that are susceptible to metabolism (CB-95, CB-101 and CB-151) and elevated proportions of PCBs that are resistant to metabolism (CB-74, CB-153, CB-138 and CB-180). The results also identified a third group of workers with elevated proportions of CB-28, CB-60, CB-66, CB-74, CB-105 and CB-118 who appeared to have been exposed to an additional source of PCBs. The results show near complete removal of the CB-95 E2 enantiomer in some samples, indicating that bioselective metabolism or preferential excretion of one enantiomer occurs in humans. By considering PCB concentrations along with detailed congener specific signatures it was possible to identify different exposure sources, and gain an insight into both the magnitude and duration of exposure.

Identifying the provenance of Leach's storm petrels in the North Atlantic using polychlorinated biphenyl signatures derived from comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

PCB signatures can be used for source identification, exposure studies, age dating and bio-monitoring. This study uses comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToFMS) to produce a PCB signature comprised of over 80 PCBs for individual Leach's storm petrels (Oceanodroma leucorhoa). The Leach's storm petrel is a relatively small, elusive, understudied pelagic bird, which only returns to remote islands under darkness during the breeding season. Samples were obtained from 25 Leach's storm petrels found dead in Canada and the UK following storm events in 2006 and 2009. Tissue samples were extracted and analysed by GCxGC-ToFMS and results showed that 83 PCB congeners were present in >60% of samples. An assessment of the PCB signature in four different tissue types showed that it did not vary greatly in samples obtained from the gut, heart, liver and stomach. Multivariate statistical analysis identified a distinctive PCB signature in birds from Canada and Europe which was used to identify the regional provenance and transatlantic movement of individual birds. The findings showcase the ability of GCxGC-ToFMS to provide the high quality congener specific analysis that is necessary for PCB fingerprinting, as well as highlighting the potential of PCB signatures for use in ecological studies of movement, foraging and behaviour.

Fingerprinting polychlorinated biphenyls in environmental samples using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

A GC × GC-TOFMS installed with a Rtx-PCB (60 m × 0.18 mm × 0.18 µm) in the first dimension and Rxi- 17 (1.5 m × 0.1 mm × 0.1 µm) column in the second dimension was used to separate 188 out of 209 congeners. A further 12 congeners were identified through additional data processing resulting in the identification of a total of 200 congeners. However, caution is advised if these 12 congeners were to be used in quantitative assessments. The remaining 9 co-eluting congeners were three doublets (CB65 + CB62, CB160 + CB163 and CB201 + CB204) and one triplet (CB20 + CB21 + CB33). This method was tested on five Aroclors and resulted in the separation of all congeners present in the heavier Aroclor mixtures A1254 and A1260. The suitability of this method for applications in biological matrices was demonstrated on extracted whiting and guillemot liver samples which resulted in the identification of 137 individual PCBs in the whiting liver sample and 120 in the guillemot sample. Fingerprinting was able to show clear differences in the PCB signature of the two animals. This highlights the potential of this method for PCB fingerprinting in environmental forensics studies and other assessments that require congener specific analysis.