Effects of Motion Sickness on Encoding and Retrieval Performance and on Psychophysiological Responses

Background: Motion sickness has previously been found to deteriorate performance. In complex working environments, sustained ability to perform despite motion sickness is crucial. This study focuses on effects of motion sickness on encoding and retrieval of words. In addition, the temporal development of psychophysiological responses and their relationship with perceived motion sickness were investigated. Methods: Forty healthy participants (20 male and 20 female, age 19-51) performed an encoding and retrieval task during exposure to an optokinetic drum and were compared with 20 controls (8 male and 12 female, age 21-47) not exposed to motion sickness. Measurements of heart rate, heart rate variability, skin conductance, blood volume pulse, respiration rate, and skin temperature were made throughout optokinetic drum exposure. Results: Moderate levels of motion sickness did not affect the ability to encode or retrieve words. Perceived motion sickness was positively related to heart rate, blood volume pulse and skin temperature and negatively related to respiration rate. Conclusions: The psychophysiological measurements did not show consistent patterns of sympathetic activation and parasympathetic withdrawal, as could be expected. Subjective reports of progressing symptoms are still likely to be the most reliable way of assessing motion sickness

Ecotoxicity of carbamazepine and its UV photolysis transformation products

Carbamazepine, an anti-epileptic pharmaceutical agent commonly found in wastewater, is highly recalcitrant to standard wastewater treatment practices. This study investigated the mixture toxicity of carbamazepine transformation products formed during UV photolysis using three standard ecotoxicity assays (representing bacteria, algae and crustaceans). UV-treatment of 6 mg L-1 carbamazepine solution was carried out over a 120 min period and samples were removed periodically over the course of the experiment. Quantification results confirmed the degradation of carbamazepine throughout the treatment period, together with concurrent increases in acridine and acridone concentrations. Ecotoxicity was shown to increase in parallel with carbamazepine degradation indicating that the mixture of degradation products formed was more toxic than the parent compound. In fact, ecotoxicity was still greater than 60 % for all three endpoints even when the carbamazepine concentration had decreased to < 1 % of the starting concentration, and acridine and acridone had decreased to < 10 % of their maximum measured concentrations. Single compound toxicity testing also confirmed the higher toxicity of measured degradation products relative to the parent compound. These results show that transformation products considerably more toxic than carbamazepine itself are likely to be produced during UV treatment of wastewater effluents and/or photo-induced degradation of carbamazepine in natural waters. This study highlights the need to consider mixture toxicity and the formation and persistence of toxicologically relevant transformation products when assessing the environmental risks posed by pharmaceutical compounds

Removal of pharmaceuticals in WWTP effluents by ozone and hydrogen peroxide

Ozonation to achieve removal of pharmaceuticals from wastewater effluents, with pH values in the upper and lower regions of the typical range for Swedish wastewater, was investigated. The main aim was to study the effects of varying pH values (6.0 and 8.0), and if small additions of H2O2 prior to ozone treatment could improve the removal and lower the reaction time. The effluents studied differed in their chemical characteristics, particularly in terms of alkalinity (65.3-427 mg center dot l(-1) HCO3-), COD (18.2-41.8 mg center dot l(-1)), DOC (6.9-12.5 mg center dot l(-1)), ammonium content (0.02-3.6 mg center dot l(-1)) and specific UV absorbance (1.78-2.76 l center dot mg(-1)center dot m(-1)). As expected, lower ozone decomposition rates were observed in the effluents at pH 6.0 compared to pH 8.0. When pH 8.0 effluents were ozonated, a higher degree of pharmaceutical removal occurred in the effluent with low specific UV absorbance. For pH 6.0 effluents, the removal of pharmaceuticals was most efficient in the effluent with the lowest organic content. The addition of H2O2 had no significant effect on the quantitative removal of pharmaceuticals but enhanced the ozone decomposition rate. Thus, H2O2 addition increased the reaction rate. In practice, this will mean that the reactor volume needed for the ozonation of wastewater effluents can be reduced