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In this study, we sought to investigate the effectiveness of inferior vena cava (IVC) filter placement in reducing the incidence of venous thromboembolism (VTE) in patients diagnosed with isolated calf deep vein thrombosis (DVT) after an intracranial hemorrhage or intracranial operation. A retrospective chart review (January 2000-December 2019) was performed to identify patients diagnosed with calf DVT after intracranial hemorrhage or intracranial operation. A total of 100 patients met the study criteria and were divided into groups based on treatment: IVC filter placement (n = 22), prophylactic anticoagulation (n = 42), or imaging surveillance (n = 36). Treatment-related complications were identified, and differences between groups in the primary endpoint (VTE occurrence after DVT diagnosis) were assessed using logistic regression. VTE occurred in 15 patients after calf DVT diagnosis. The rate of VTE was higher in the IVC filter group (9/22; 41%) than in the anticoagulation (2/42; 5%; p = 0.002) and surveillance (4/36; 11%; p = 0.013) groups. These treatment effects remained significant after adjustments were made for baseline characteristics (IVC filter vs anticoagulation, p = 0.009; IVC filter vs surveillance, p = 0.019). There was a single occurrence of pulmonary embolism in the surveillance group (3%). A single case of IVC filter thrombus was identified; no anticoagulation-related complications were reported. The findings of this study do not support IVC filter placement as a primary and solitary treatment for isolated calf DVT occurring after intracranial hemorrhage or intracranial operation.

Polychlorinated biphenyl (PCB) input–output balance studies were performed on five male volunteers, aged between 24 and 30, for periods of 8–14 days in 1998. Dietary exposure was quantified by the duplicate meals method and varied between 220 and 460 ng of ∑PCB (sum of 20 congeners) per day for each of the five individuals over the study period. Dietary intake was dominated by congeners 118, 138, 153 and 180. Average faecal outputs for the five volunteers were 50–290 ng of ∑PCB (sum of 20 congeners) per day for each of the five individuals over the same period and was dominated by the same four congeners. Whilst the total PCB fluxes were therefore into the body (i.e., accumulation), important differences were noted for different individual congeners. PCBs 44, 47, 49, 52, 60, 66, 101, 105, 110, 118, 149, 151 and 183 all showed net absorption for all five volunteers. Some congeners showed a net absorption in some of the individuals but net excretion in others, as seen by other workers. These congeners (PCBs 138, 153, 180, 187 and 194) are all higher chlorinated congeners and lack meta-para-vicinal hydrogen atoms. There were differences in the net absorption/excretion between individuals, which appeared to be a function of body fat index (BFI). The volunteers with the lowest BFIs showed net excretion for the greatest number of congeners, whilst the individual with the highest BFI was a net absorber of all the congeners studied. The problems in determining and interpreting absorption efficiency values for use in quantitative exposure assessments are discussed. Various factors that influence net absorption of PCBs and other persistent organic pollutants are identified. These include compound properties (including susceptibility to metabolism), the individual's fat status and balance, exposure history and diet. Keywords: Polychlorinated biphenyls, Organochlorine, Metabolism, Excretion, Blood

Seasonal variations of biogenic volatile organic compound (VOC) emission rates and standardised emission factors from gorse (Ulex europaeus) have been measured at two sites in the United Kingdom, from October 1994 to September 1995, within temperature and PAR conditions ranging from 3 to 34°C and 10–1300 μmol m−2 s−1, respectively. Isoprene was the dominant emitted compound with a relative composition fluctuating from 7% of the total VOC (winter) to 97% (late summer). The monoterpenes α-pinene, camphene, sabinene, β-pinene, myrcene, limonene, trans-ocimene and γ-terpinene were also emitted, with α-pinene being the dominant monoterpene during most the year. Trans-ocimene represented 33–66% of the total monoterpene during the hottest months from June to September. VOC emissions were found to be accurately predicted using existing algorithms. Standard (normalised) emission factors of VOCs from gorse were calculated using experimental parameters measured during the experiment and found to fluctuate with season, from 13.3±2.1 to 0.1±0.1 μg C (g dwt)−1 h−1 in August 1995 and January 1995, respectively, for isoprene, and from 2.5±0.2 to 0.4±0.2 μg C (g dwt)−1 h−1 in July and November 1995, respectively, for total monoterpenes. No simple clear relation was found to allow prediction of these seasonal variations with respect to temperature and light intensity. The effects of using inappropriate algorithms to derive VOC fluxes from gorse were assessed for isoprene and monoterpenes. Although on an annual basis the discrepancies are not significant, monthly estimation of isoprene were found to be overestimated by more than a factor of 50 during wintertime when the seasonality of emission factors is not considered.

A method was developed to determine trace concentrations of a range of individual PCB congeners in biological samples (serum, food and faeces) using GC-MS, to prepare a mass balance of PCBs in humans. A simple method for the analysis of PCBs in human serum, which excluded an extraction step, was first employed. Results indicated that the recoveries of 13C12 PCB spikes were variable. A soxhlet extraction step was added and was found to be efficient and reproducible. A quality control routine and method validation results are presented. In batch tests of the methods presented it was found that the serum analysis method gave within batch mean 13C12 spike recoveries of 98 – 120% and standard deviations between 6 and 20%. The food/faeces analysis method gave within-batch mean 13C12 spike recoveries of 88 – 100%, and within batch standard deviations between 4 and 12%. The batch to batch mean recovery for serum analysis was 100%, with an RSD of 9% for high spikes and 10% for low spikes. For food/faeces analysis the batch to batch average recovery was 110%, with an RSD of 5% for high spikes and 9% for low spikes.

The statistical treatment of data-sets from environmental pollutant studies in which different measurements are combined to produce averages or comparative factors (e.g., transfer coefficients (TCs), input–output balance values) are considered here, with particular reference to the analysis of data from input–output balance studies of pollutants such as PCBs in animals and humans. Many methods of statistical analysis ignore the fact that all measurements are subject to error, and generally assume that the normal distribution applies to all data-sets, which is commonly inappropriate for environmental (and particularly biological system) data. Considerably different estimations can be obtained by applying different, commonly used, statistical methods, as shown in a simulation study presented here and when applied to data from an input–output balance study of PCBs in humans. Alternative average and combined factor estimators for the treatment of data from these types of studies that give considerable advantages in terms of bias and the ease of assessment of accuracy are proposed.

We have developed a model which successfully reconstructs the lifetime polychlorinated biphenyl (PCB)-101 burden of the UK population for individuals born between 1920 and 1980. It not only follows burdens and clearance of persistent organic contaminants throughout a human lifetime — taking changes in age and body composition into account — but also, importantly, incorporates changing environmental concentrations of the compound of interest. Predicted results agree well with available measured lipid concentrations in human tissues. Its unique construction takes into account both changing environmental concentrations of PCBs in principal food groups and changing dietary habits during the time period. Because environmental burdens of persistent organic contaminants have changed over the last 60 years, residues in food will also have mirrored this change. Critically in this respect, the year in which an individual was born determines the shape and magnitude of their exposure profile for a given compound. Observed trends with age represent an historical legacy of exposure and are not simply a function of equal yearly cumulative inputs. We can demonstrate that the release profile of PCB-101 controls levels in the food supply and ultimately the burden of individuals throughout their life. This effect is expected to be similar for other PCB congeners and persistent organic compounds such as polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs). Models of this type have important applications as predictive tools to estimate the likely impact of source-reduction strategies on human tissue concentrations.