Influence of solvent exposure and aging on cognitive functioning: an 18 year follow up of formerly exposed floor layers and their controls

Abstract

Objectives: To extend our knowledge of how exposure to neurotoxic substances during working life affects cognitive functioning in the long term. Does long term occupational exposure to organic solvents lead to aggravated cognitive impairment later in life? Methods: A follow up was conducted of floor layers exposed to solvents and their unexposed referents (carpenters) 18 years after the baseline assessment. The pattern of cognitive changes in the two groups was compared, with the same 10 neuropsychological tests from the test battery for investigating functional disorders (TUFF) that were used at baseline. The study included 41 floor layers and 40 carpenters. A medical examination focused on health at the present and during the past 18 years. An extensive exposure assessment made in the initial study included questionnaires, interviews, and measurements. Additional exposure during the follow up period was minor, as explored in interviews at follow up. Results: The entire group of floor layers did not deteriorate significantly more over time than did the carpenters. However, among the oldest subjects (>60 years), only floor layers showed decline in visual memory. Moreover, the most highly exposed floor layers deteriorated significantly more than their referents in visual memory and perceptual speed, and they tended to display larger decrements in motor speed. Significant dose effect relations were found; higher cumulative exposure was associated with decrements in visual episodic memory, perceptual speed and attention, and visuospatial skill. Conclusions: The hypothesis that floor layers would deteriorate more in cognitive performance than their unexposed referents over a period of 18 years was partly supported by the results of this study. The results are consistent with the view that the negative effects of exposure to solvents may interact with the normal aging process, primarily at heavy exposure.

Effects of long-term low-level solvent exposure on cognitive function

“…e cognitive domains a ected by solvent exposures include attention, verbal memory, and visuospatial skills [69,70]. ere is some evidence that solvent neurotoxicity is commoner among those with at least 10 years of occupational exposure to solvents.…”

Longitudinal Study to Explore Chronic Neuropsychologic Effects on Solvent Exposed Workers

“…An important shortcoming of any longitudinal study may be the occurrence of dropouts. In comparison to the two formally mentioned follow-up studies, with dropouts of 55% after 2 yr and 19% after 18 yr respectively, the dropout in this study (30%) is acceptable 9,11) . Within the two year period, 50 workers left their workplace.…”

“…White et al examined workers during the shift and again after one year 10) . Finally Nilson et al performed an 18 yr follow up of formerly exposed floor layers 11) . The results of these studies indicate that the prognosis of CNS-impairment depends on the length and intensity of exposure to the solvents and elapse of time since cessation of exposure.…”

Organic solvents as chemical risk factors of the work environment in different branches of industry and possible impact of solvents on workers' health

“…During the two last decades epidemiological research has described a relationship between lasting occupational exposure to organic solvents and non-specific symptoms, such as headache, fatigue, irritability, memory disturbances, reduced intellectual abilities, concentration difficulties, emotional instability, depression, sleep disorders, reduced alcohol tolerance, reduction of libido and potency and alters aging processes (Xiao, 2000;Nilson, 2002).…”