Probabilistic cumulative risk assessment of anti-androgenic pesticides in food

In this paper, we present a cumulative risk assessment of three anti-androgenic pesticides (vinclozolin, procymidone and prochloraz) using the relative potency factor (RPF) approach and an integrated probabilistic risk assessment (IPRA) model. RPFs for each substance were estimated for three reproductive endpoints (ano-genital distance, and weights of the seminal vesicles and the musculus levator ani/bulbocavernosus) in male rat foetuses exposed in utero. The cumulative dietary intake was estimated based on consumption data and residue data from the Netherlands. The IPRA model combines variability in both exposure and sensitivity between individuals into a distribution of individual margins of exposures (IMoEs) and IMoEs of 1 or less indicate a possible concern.     

Between‐hospital variation in rates of complications and decline of patient performance after glioblastoma surgery in the dutch Quality Registry Neuro Surgery

Journal of Neuro-Oncology - For decisions on glioblastoma surgery, the risk of complications and decline in performance is decisive. In this study, we determine the rate of complications and...     

Gamma knife radiosurgery for recurrent gliomas

Objective

In recent years, gamma knife radiosurgery (GKRS) has become increasingly more popular as a salvage treatment modality for patients diagnosed with recurrent gliomas. The goal of GKRS for recurrent glioma patients is to improve survival rates with minimal burden for these patients. The emphasis of this report is on local tumor control (TC), clinical outcome and survival analysis.

Methods

We performed a retrospective analysis of prospectively collected data of all patients who underwent GKRS for gliomas at the Gamma Knife Center Tilburg between 23-09-2002 and 21-05-2015. In total, 94 patients with glioma were treated with GKRS. Two patients were excluded because GKRS was used as a first stage treatment. The other 92 patients were included for analysis.

Results

TC was 37% for all tumors (TC was 50% in LGGs and 27% in HGGs). Local progression (LP) was 46% for all tumors (LP was 31% in LGGs and 58% in HGGs). New distant lesions were seen in 18% of all patients (in 5% of LGG patients and 31% of HGG patients). Median progression-free and overall survival (PFS and OS) for all patients were 10.5 and 34.4 months, respectively. Median PFS was 50.1 and 5.7 months for low and high grade tumors, respectively. Median OS was 86.6 and 12.8 months for low and high grade tumors, respectively. No serious adverse events were noted post-GKRS.

Conclusion

GKRS can safely be used as salvage treatment for recurrent glioma and seems to improve survival rates in (high grade) glioma patients with minimal burden.

     

Comparison of human health risks resulting from exposure to fungicides and mycotoxins via food

The interest in holistic considerations in the area of food safety is increasing. Risk managers may face the problem that reducing the risk of one compound may increase the risk of another compound. An example is the potential increase in mycotoxin levels due to a reduced use of fungicides in crop production. The Integrated Probabilistic Risk Assessment (IPRA) model was used to compare the estimated health impacts on humans caused by crops contaminated with the fungicides spiroxamine (SPI) and tebuconazole (TEB) or with the mycotoxins deoxynivalenol (DON) and zearalenone (ZEA). The IPRA model integrates a distribution characterising the exposure of individuals with a distribution characterising the susceptibility of individuals towards toxic effects. Its outcome, a distribution of Individual Margins of Exposure (IMoE), served as basis to perform comparisons of compounds, effects, countries, and population groups. Based on the available data and the assumptions made, none of the four compounds was found to have impact on human health in the addressed scenarios. The IMoE distributions were located as follows: DON < TEB = ZEA < SPI, showing DON to be the compound with the highest potential for negative health impacts. The presented approach can help risk managers to prioritise risk-reduction measures.     

Can current dietary exposure models handle aggregated intake from different foods? A simulation study for the case of two foods

Current dietary exposure models provide estimates of long-term intake distributions using short-term food consumption survey data, by statistically modeling the aggregated intakes from different foods consumed on the same day for each participant of the survey. Food consumption behaviour in a population may, however, show all sorts of correlations which are not modelled in these exposure models. We developed a simulation model describing a hypothetical population of consumers, assuming various types of correlation between two foods. Using this simulation model we found that the impact of the correlations in many cases is limited, but in particular circumstances it can be substantial, depending on the properties of the marginal distributions. Further, we found that the usual approach of first aggregating the observed intakes over foods, and then applying the statistical exposure models to the total daily intakes may lead to deviating results, even when all correlations are assumed to be zero. The approach of analyzing the intakes from the separate foods, and then aggregating the results from the statistical model applied to each food performed much better. Our results illustrate that the simulation model can be used for validating dietary exposure models, and for indicating how exposure models may be improved.     

Measurements of the dose distribution in mantle fields

A polystyrene phantom has been constructed which is a model for a reference case employed by the Centers for Radiological Physics in their assessment of irregular field calculation methods. Considerations in the phantom design are given. Measurements of the dose distribution determined in the irradiation of this phantom by 13 machines in the energy range from Co-60 to 15 MV X rays are reported. The clinical significance of the variations observed is discussed. The results clearly demonstrate the need for off-axis calculations in the mantle irradiations and suggest that the off-axis energy change in linear accelerator beams is an important parameter in the dose calculations.     

Pion treatment procedures and verification techniques

Procedures and techniques developed for the negative pi-meson (pion) radiotherapy program at the Los Alamos Meson Physics Facility, Los Alamos, NM, are reviewed and described. A particular pion patient is followed through the entire planning and treatment sequence to describe CT scanning procedures, bolus and collimator and treatment techniques developed to minimize positioning errors (less than 5 mm). Comparison of 2-D and 3-D isodose calculations developed at Los Alamos showed differences of less than 10% attributable to multiple scattering effects and the computational models used. Treatment verification methods using in vivo ion chamber dosimetry generally confirmed the prescribed dose delivery within 10% and using TLD within 18%.     

Thermoluminescence of 7LiF in therapeutic high linear energy transfer (LET) charged-particle beams

The thermoluminescence of the 200 and 260 degrees C peaks of 7LiF has been measured and compared with off-axis dose and depth-dose distributions for three therapeutic high-LET beams: negative pions, helium ions and neon ions. The methods of analysis consisted of both a single-peak analysis and the dual-peak analysis methods of Hogstrom and Irifune and Hoffmann et al. The results indicate that 7LiF, analysed by the dual-peak analysis methods, is potentially useful for extracting total dose, high-LET dose, and beam quality of helium-ion and negative-pion beams. For the higher-LET neon beam, differences in sensitivity between the 200 and 260 degrees C peaks of 7LiF were found to be independent of variations in LET within the beam; consequently, only the single-peak analysis method is applicable in which case the dosemeter at best can only estimate total dose.