[Exposure to traffic noise and effects on attention]

This study was aimed to evaluate if workers exposed to environmental stressors, including the urban traffic noise, might show significant differences compared to a control group in neuro-psychological and emotional profile as well as neurophysiological functions. In particular if these differences could be evidenced by the application of the "oddball paradigm" for event related potential P300 component. The study consisted of the following examinations: (1) exposed workers vs. controls under the odd-ball paradigm and the Stroop test in baseline condition; (2) amplitude and latency ofP300 (in baseline condition and after administration of acute urban traffic noise and Stroop test). The research was carried on a sample of 81 volunteers: 39 workers exposed to environmental stressors and 42 controls. The phonometric measurements showed mean levels of noise due urban traffic like 74 dBAeq. In baseline condition significative differences in exposed workers vs. control were found in Raven's Matrices PM 38 (p = 0.002) and Arithmetic reasoning from WAIS-R (p = 0.0024). Attention capacities as measured by Digit Span Forward and Visual Search, emotional functioning as measured by state- and trait-anxiety test and mood profile were not different in the two groups. Either in baseline condition or after acute stimuli no significant changes were found in two groups concerning the odd-ball paradigm. Exposed workers showed a higher execution time at Stroop test compared to controls (p = 0.047). No differences were found in the number of errors at the Stroop test. Before the acute stimulus, P300 amplitude was significant higher in the exposed workers than in controls (p = 0.002) while the latency was not different between two groups. Both noise (p = 0.001) and Stroop test (p = 0.002) stimulation increased the P300 latency of the whole sample, without significant differences between exposed workers and controls. A significative decrease of P300 amplitude due noise both in the exposed workers (p = 0.001) and in controls (p = 0.012) was found, without significant difference between the two groups. These results are interpreted as follows: (1) there are chronic effects on cognitive functioning in the exposed group vs. controls in baseline condition, like showed by significant differences in Raven PM38 and WAIS-R; (2) the exposed workers have a smaller cognitive flexibility, as shown by the Stroop test results; (3) in baseline condition the greater P300 amplitude in exposed workers reflect a greater division of attentive resources vs. controls, probably linked to the chronic stimulation by environmental stressors, especially noise, to which these workers are exposed; (4) the effects on P300 latency and amplitude can document the physiological response both in the exposed and not exposed to the acute stimulus and that the lack of significative differences in P300 latency and amplitude may be due to adaptative response to acute stimuli in exposed too. Our results allow us to consider that in workers exposed to urban stressor, such as noise, there are effects on cognitive functioning, especially on attention, without auditory damages. The valuation of P300 might represent a valid diagnostic instrument to evaluate the effects on cognitive functions especially on attention, in workers chronically and acutely exposed to urban stressors.