A cell-free testing platform to screen chemicals of potential neurotoxic concern across twenty vertebrate species

There is global demand for new in vitro testing tools for ecological risk assessment. The objective of the present study was to apply a set of cell-free neurochemical assays to screen many chemicals across many species in a relatively high-throughput manner. The platform assessed 7 receptors and enzymes that mediate neurotransmission of γ-aminobutyric acid, dopamine, glutamate, and acetylcholine. Each assay was optimized to work across 20 vertebrate species (5 fish, 5 birds, 7 mammalian wildlife, 3 biomedical species including humans). We tested the screening assay platform against 80 chemicals (23 pharmaceuticals and personal care products, 20 metal[loid]s, 22 polycyclic aromatic hydrocarbons and halogenated organic compounds, 15 pesticides). In total, 10 800 species-chemical-assay combinations were tested, and significant differences were found in 4041 cases. All 7 assays were significantly affected by at least one chemical in each species tested. Among the 80 chemicals tested, nearly all resulted in a significant impact on at least one species and one assay. The 5 most active chemicals were prochloraz, HgCl₂ , Sn, benzo[a]pyrene, and vinclozolin. Clustering analyses revealed groupings according to chemicals, species, and chemical-assay combinations. The results show that cell-free assays can screen a large number of samples in a short period of time in a cost-effective manner in a range of animals not easily studied using traditional approaches. Strengths and limitations of this approach are discussed, as well as next steps. Environ Toxicol Chem 2017;36:3081-3090. © 2017 SETAC.

Sick leave among people in paid work after age 65: A Swedish population-based study covering 1995, 2000, 2005 and 2010

Aims: Extending working life into older age groups is discussed in many countries. However, there is no knowledge about how this affects rates of sick leave. The aim of this work was to investigate rates of sick leave among people in paid work after retirement age and if such rates have changed over time. Methods: Swedish nationwide register data on people aged >65 years and living in Sweden in 1995, 2000, 2005 and 2010 were analysed. All people with a sufficiently high work income to be eligible for public sick leave benefits were included. The proportions in paid work and compensated rates of sick leave for people aged 66–70 and ≥71 were analysed by sex, educational level, country of birth, living area, and employment type and sector. Results: The percentage of people in paid work at ages 66–70 years increased from <10% in 1995 to 24% in 2010 and among those aged ≥71 years from 2.7% in 1995 to 3.5% in 2010. The rates of sick leave among working people aged 66–70 years were 3.3% in 1995 and 2.4% in 2010 and for people aged ≥71 years the rates of sick leave were 2.2% in 1995 and 0.2% in 2010. Women had higher rates of sick leave than men in 2005 and 2010, but lower in 1995 and 2000. In 2010, the rates of sick leave were similar between employees and the self-employed, and higher among employees in the public sector than among employees in the private sector. Conclusions: Rates of sick leave among workers aged >65 years were lower in 2010 than in 1995, despite much higher rates of labour market participation in 2010.

Developmental Methylmercury Exposure Affects Swimming Behavior and Foraging Efficiency of Yellow Perch (Perca flavescens) Larvae

Methylmercury (MeHg) is a pervasive and ubiquitous environmental neurotoxicant within aquatic ecosystems, known to alter behavior in fish and other vertebrates. This study sought to assess the behavioral effects of developmental MeHg exposure on larval yellow perch (Perca flavescens)-a nonmodel fish species native to the Great Lakes. Embryos were exposed to MeHg (0, 30, 100, 300, and 1000 nM) for 20 h and then reared to 25 days post fertilization (dpf) for analyses of spontaneous swimming, visual motor response (VMR), and foraging efficiency. MeHg exposures rendered total mercury (THg) body burdens of 0.02, 0.21, 0.95, 3.14, and 14.93 μg/g (wet weight). Organisms exposed to 1000 nM exhibited high mortality; thus, they were excluded from downstream behavioral analyses. All MeHg exposures tested were associated with a reduction in spontaneous swimming at 17 and 25 dpf. Exposure to 30 and 100 nM MeHg caused altered locomotor output during the VMR assay at 21 dpf, whereas exposure to 100 nM MeHg was associated with decreased foraging efficiency at 25 dpf. For the sake of comparison, the second-lowest exposure tested here rendered a THg burden that represents the permissible level of consumable fish in the United States. Moreover, this dose is reported in roughly two-thirds of consumable fish species monitored in the United States, according to the Food and Drug Administration. Although the THg body burdens reported here were higher than expected in the environment, our study is the first to analyze the effects of MeHg exposure on fundamental survival behaviors of yellow perch larvae and advances in the exploration of the ecological relevance of behavioral end points.

Impact of childhood and adulthood psychological health on labour force participation and exit in later life

BACKGROUND

Adulthood psychological health predicts labour force activity but few studies have examined childhood psychological health. We hypothesized that childhood psychological ill-health would be associated with labour force exit at 55 years.

METHOD

Data were from the 55-year follow-up of the National Child Development Study (n = 9137). Labour force participation and exit (unemployment, retirement, permanent sickness, homemaking/other) were self-reported at 55 years. Internalizing and externalizing problems in childhood (7, 11 and 16 years) and malaise in adulthood (23, 33, 42, 50 years) were assessed. Education, social class, periods of unemployment, partnership separations, number of children, and homemaking activity were measured throughout adulthood.

RESULTS

Childhood internalizing and externalizing problems were associated with unemployment, permanent sickness and homemaking/other at 55 years, after adjustment for adulthood psychological health and education: one or two reports of internalizing was associated with increased risk for unemployment [relative risk (RR) 1.59, 95% confidence interval (CI) 1.12-2.25; RR 2.37, 95% CI 1.48-3.79] and permanent sickness (RR 1.32, 95% CI 1.00-1.74; RR, 1.48, 95% CI 1.00-2.17); three reports of externalizing was associated with increased risk for unemployment (RR 2.26, 95% CI 1.01-5.04), permanent sickness (RR 2.63, 95% CI 1.46-4.73) and homemaking/other (RR 1.95, 95% CI 1.00-3.78).

CONCLUSIONS

Psychological ill-health across the lifecourse, including during childhood, reduces the likelihood of working in older age. Support for those with mental health problems at different life stages and for those with limited connections to the labour market, including homemakers, is an essential dimension of attempts to extend working lives.

Informal caregiving as a risk factor for type 2 diabetes in individuals with favourable and unfavourable psychosocial work environments: A longitudinal multi-cohort study

AIM

To examine whether informal caregiving is associated with increased risk of type 2 diabetes (T2D), and whether job strain and social support at work modify the association.

METHODS

Individual participant's data were pooled from three cohort studies-the French GAZEL study, the Swedish Longitudinal Occupational Survey of Health (SLOSH) and the British Whitehall II study-a total of 21,243 study subjects. Informal caregiving was defined as unpaid care for a closely related person. Job strain was assessed using the demand-control model, and questions on co-worker and supervisor support were combined in a measure of social support at work. Incident T2D was ascertained using registry-based, clinically assessed and self-reported data.

RESULTS

A total of 1058 participants developed T2D during the up to 10 years of follow-up. Neither informal caregiving (OR: 1.09, 95% CI: 0.92-1.30) nor high job strain (OR: 1.04, 95% CI: 0.86-1.26) were associated with T2D risk, whereas low social support at work was a risk factor for T2D (OR: 1.18, 95% CI: 1.02-1.37). Also, informal caregivers who were also exposed to low social support at work were at higher risk of T2D (OR: 1.40, 95% CI: 1.08-1.82) compared with those who were not informal caregivers and had high social support at work (multiplicative test for interaction, P=0.04; additive test for interaction, synergy index=10).

CONCLUSION

Informal caregiving was not independently associated with T2D risk. However, low social support at work was a risk factor, and informal caregivers with low social support at work had even higher risks of T2D.

Parental Whole Life Cycle Exposure to Dietary Methylmercury in Zebrafish (Danio rerio) Affects the Behavior of Offspring

Methylmercury (MeHg) is an established neurotoxicant of concern to fish-eating organisms. While most studies have focused on the fish consumers, much less is known about the effects of MeHg on the fish themselves, especially following exposures to chronic and environmentally relevant scenarios. Here we evaluated the behavioral effects of developmental MeHg insult by exposing parental generations of zebrafish to an environmentally realistic MeHg dietary concentration (1 ppm) and two higher concentrations (3 and 10 ppm) throughout their whole life span. Upon reaching adulthood, their offspring were analyzed through a series of behavioral tests, including the visual-motor response (VMR) assay, analysis of spontaneous swimming and evaluation of foraging efficiency. The VMR assay identified decreased locomotor output in the 6 day postfertilization (dpf) offspring of fish exposed to 3 and 10 ppm MeHg. However, in a second test 7 dpf fish revealed an increase in locomotor activity in all MeHg exposures tested. Increases in locomotion continued to be observed until 16 dpf, which coincided with increased foraging efficiency. These results suggest an association between MeHg and hyperactivity, and imply that fish chronically exposed to MeHg in the wild may be vulnerable to predation.

Serum C-reactive protein levels predict regional brain responses to noxious cold stimulation of the hand in chronic whiplash associated disorders

BACKGROUND AND AIMS

Whiplash Associated Disorders (WAD) are a costly health burden. The condition is characterised by sensory disturbances such as widespread hyperalgesia likely indicative of central hyperexcitability. Recently elevated levels of pro-inflammatory biomarkers have also found in acute and chronic WAD. The aim of this cross-sectional study was to investigate the relationship between inflammatory biomarkers and pain processing in people with persistent whiplash associated disorders (WAD).

METHODS

Twenty one participants with chronic whiplash (>3 months) were recruited. Venous blood samples were collected and assays performed for C-reactive protein (CRP) and TNF-α. Blood oxygen level-dependent (BOLD) contrast images of the brain were acquired with a Siemens 1.5T MRI scanner during repeated 24s stimulus blocks of innocuous or painful stimuli (thumbnail pressure and cold stimulation of dorsum of hand) separated by 36s inter-stimulus intervals. Stimulus intensities used during scanning were at the level of participants' thresholds for moderate pain. Parameter estimates representing BOLD signal increases during painful events from each participant were tested for associations with inflammatory biomarkers.

RESULTS

Clinically relevant levels of CRP and TNF-α were found in 33% and 38% of participants. Levels of CRP showed a positive correlation with levels of cold pain activation in brain regions including the anterior insula, posterior parietal cortex, caudate and thalamus (p_corrected<0.05). Levels of TNF-α were not related to activation levels during either noxious pressure or cold. Pressure pain activations also did not show a relationship with CRP levels.

CONCLUSIONS

Shared variance between inflammation and increased levels of regional pain-related activation in people with persistent whiplash symptoms is apparent for cold, but not pressure stimuli.

IMPLICATIONS

The results highlight cold pain processing as an important aspect of whiplash chronicity, although the implications of this modality-specific effect are not readily apparent.

Psychosocial factors associated with work disability in men and women with diabetes: a pooled analysis of three occupational cohort studies

AIMS

To examine the extent to which adverse psychosocial factors, such as living alone, psychological distress, job strain and low support from supervisor, increase the risk of work disability (sickness absence and disability pension) among employees with diabetes.

METHODS

In this pooled analysis of individual-participant data from three occupational cohort studies (the Finnish Public Sector Study, the British Whitehall II study, and the French GAZEL study), 1088 women and 949 men with diabetes were followed up to determine the duration (number of days) and frequency (number of spells) of work disability. The mean follow-up periods were 3.2 years in the GAZEL study, 4.6 years in the Whitehall II study and 4.7 years in the Finnish Public Sector Study. Psychosocial factors and potential confounding factors were assessed at baseline using standard questionnaires. Study-specific estimates were pooled using fixed-effects meta-analysis.

RESULTS

In analysis adjusted for sociodemographic factors, health behaviours and comorbidities, participants with psychological distress had longer (rate ratio 1.66; 95% CI 1.31-2.09) and more frequent absences (rate ratio 1.33; 95% CI 1.19-1.49) compared with those with no psychological distress. Job strain was associated with slightly increased absence frequency (rate ratio 1.19 95% CI 1.05-1.35), but not with absence duration. Living alone and low supervisor support were not associated with absence duration or frequency. We observed no sex differences in these associations.

CONCLUSIONS

Psychological distress was associated with increased duration and frequency of work disability among employees with diabetes. Job strain was associated with increased absence frequency but not with absence duration.

Lifestyle-related risk factors and trajectories of work disability over 5 years in employees with diabetes: findings from two prospective cohort studies

AIMS

To examine work disability trajectories among employees with and without diabetes and identify lifestyle-related factors associated with these trajectories.

METHODS

We assessed work disability using records of sickness absence and disability pension among participants with diabetes and age- sex-, socio-economic status- and marital status-matched controls in the Finnish Public Sector Study (1102 cases; 2204 controls) and the French GAZEL study (500 cases; 1000 controls), followed up for 5 years. Obesity, physical activity, smoking and alcohol consumption were assessed at baseline and the data analysed using group-based trajectory modelling.

RESULTS

Five trajectories described work disability: 'no/very low disability' (41.1% among cases and 48.0% among controls); 'low-steady' (35.4 and 34.7%, respectively); 'high-steady' (13.6 and 12.1%, respectively); and two 'high-increasing' trajectories (10.0 and 5.2%, respectively). Diabetes was associated with a 'high-increasing' trajectory only (odds ratio 1.90, 95% CI 1.47-2.46). Obesity and low physical activity were similarly associated with high work disability in people with and without diabetes. Smoking was associated with 'high-increasing' trajectory in employees with diabetes (odds ratio 1.88, 95% CI 1.21-2.93) but not in those without diabetes (odds ratio 1.32, 95% CI 0.87-2.00). Diabetes was associated with having multiple ( ≥ 2) risk factors (21.1 vs. 11.4%) but the association between multiple risk factors and the 'high-increasing' trajectory was similar in both groups.

CONCLUSIONS

The majority of employees with diabetes have low disability rates, although 10% are on a high and increasing disability trajectory. Lifestyle-related risk factors have similar associations with disability among employees with and without diabetes, except smoking which was only associated with poorer prognosis in diabetes.