Multiple linear regression based congener profile correlation to estimate the toxicity (TEQ) and dioxin concentration in atmospheric emissions.

The formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) is governed by complex chemical reactions with complex kinetic models. The simulation of Municipal Solid Waste incinerators, or other industrial thermal processes, is a powerful tool that can be used to optimize and control them, and reducing the number of components to simulate is mandatory for a proper use. In this study it has been determined that only the formation of 3 of the 17 main PCDD/F congeners can be considered as linearly independent. This fact has been used to establish linear regression models that are able to estimate properly the total amount and toxicity of a sample considering only the amount of 1,2,3,6,7,8-HxCDD, OCDF and 2,3,7,8-TCDF. All models have been validated using new samples performing a close approach to the real values provided by complete analytical studies. The average relative error is 3.5% and the maximum relative error is below 9% for these new testing samples. The main goal of our investigation is to build a dynamic simulation process of a MSW facility and include the dioxins formation on it using these models.

Aphysiologic performance on dynamic posturography in work-related patients.

It has been suggested that malingering should be suspected in patients suffering from dizziness or imbalance and who had a potential gain associated with insurance and worker's compensation claims. This study aimed to assess and compare the prevalence of aphysiologic performance on computerized dynamic posturography (CDP) in patients with the potential for secondary gain using a retrospective review of two groups of patients: work-related patients referred for dizziness and/or imbalance (Group 1) were compared against a group of patients with complaints of dizziness or imbalance, who had no history of work-related injury, or litigation procedures (Group 2). CDP and videonystagmography (VNG) were carried out in all patients. The Sensory Organization Test summaries were scored as normal, aphysiologic, or vestibular using the scoring method published by Cevette et al. in Otolaryngol Head Neck Surg 112:676-688 (1995). 24 out of 88 (27%) patients had aphysiologic CDP in Group 1 and 9 out of 51 (18%) in Group 2 but these differences were not significant (p > 0.05). Definite signs of vestibular dysfunction were found in 12 out of 24 (50%) of patients with aphysiologic performance in Group 1 although the presence of VNG abnormalities was significantly higher (p = 0.005) in Group 2. The hypothesis that the occupational group could show a significantly higher rate of aphysiologic results than a control group is not confirmed. Furthermore, VNG abnormalities were found in 50% of the work-related cases with non organic sway patterns. These results suggest that patient's complaints should be considered genuine in work-related cases and due caution exercised when evaluating aphysiologic CDP patterns.