IARC-NCI workshop on an epidemiological toolkit to assess biases in human cancer studies for hazard identification: beyond the algorithm

The role of study quality in aspartame and cancer epidemiology study reviews

Toews et al. [1] and the World Health Organization (WHO) [2] reviewed observational epidemiology studies of non-sugar sweeteners (NSSs) and various health effects. The former used the Risk of Bias in Non-randomised Studies - of Interventions (ROBINS-I) tool and the latter used both the ROBINS-I tool and the Newcastle-Ottawa Scale to evaluate study quality. Both reviews concluded that there were no associations between NSS or aspartame consumption and cancer (except possibly between saccharin and bladder cancer) but indicated that the certainty of the evidence for all cancer types was "very low." While we agree with this conclusion, the support for the confidence in the evidence generally was not transparently documented, as the results of the study quality assessment were only provided in scores or ratings. An examination of illustrative case studies shows that some important aspects of study quality domains specific for NSSs generally or aspartame specifically (i.e., issues with the exposure and outcome assessments, the consideration of confounding/covariates, and selection bias) may have been overlooked or not given appropriate consideration, while other aspects that were less likely to have a large impact on overall study quality dominated the results in the two assessments. Our review of other studies published after the WHO [2] review further demonstrates this point. While this may not seem important given the overall lack of associations, it impacts the degree to which evidence supports a lack of effects as opposed to not being adequate to evaluate associations. In the future, aspartame and cancer outcome reviews should focus on those study quality domains that are most likely to impact the interpretation of results and discuss them in a transparent, systematic manner. If there is very low certainty in the evidence as a result of low study quality, reviewers should conclude the evidence is inadequate for making a causal determination.

Organizational interventions and occupational burnout: a meta-analysis with focus on exhaustion

PURPOSE

To assess whether organizational interventions are effective to prevent or reduce exhaustion, the core dimension of occupational burnout.

METHODS

We searched in PubMed, EMBASE, PsycINFO, and Cochrane Library databases randomized and non-randomized controlled trials conducted among active workers and reporting the outcome as exhaustion score. We calculated the effect sizes using the pre-test-post-test control group design's estimate. We used the random effects model in meta-analysis and Cochrane collaboration's tool for interventions to assess the risk of bias. Overall quality of evidence was appraised using the GRADE.

RESULTS

From the 2425 identified records, we assessed 228 full texts for eligibility and included 11 original articles describing 13 studies, 11 on organizational interventions, and 2 on combined inventions. The interventions were participatory (n = 9), focused on workload (n = 2), or on work schedule (n = 2). The overall effect size was - 0.30 ((95% CI = - 0.42; - 0.18), I2 = 62.28%), corresponding to a small reduction in exhaustion with a very low quality of evidence. Combined interventions had a larger effect (- 0.54 (95% CI = - 0.76; - 0.32)) than organizational interventions. When split by type of intervention, both participatory interventions and interventions focused on workload had a benefic effect of exhaustion reduction, with an estimated effect size of - 0.34 (95% CI = - 0.47; - 0.20) and - 0.44 (95% CI = - 0.68, - 0.20), respectively.

CONCLUSION

Interventions at combined level in workplaces could be helpful in preventing exhaustion. However, the evidence is still limited, due to a high heterogeneity between studies, bias potential, and small number of eligible studies. This calls for further research, using workload interventions at organizational level, especially in sectors with high risk of job stress and exhaustion.

Research Recommendations for Selected IARC-Classified Agents: Impact and Lessons Learned

BACKGROUND

The International Agency for Research on Cancer (IARC) Monographs program assembles expert working groups who publish a critical review and evaluation of data on agents of interest. These comprehensive reviews provide a unique opportunity to identify research needs to address classification uncertainties. A multidisciplinary expert review and workshop held in 2009 identified research gaps and needs for 20 priority occupational chemicals, metals, dusts, and physical agents, with the goal of stimulating advances in epidemiological studies of cancer and carcinogen mechanisms. Overarching issues were also described.

OBJECTIVES

In this commentary we review the current status of the evidence for the 20 priority agents identified in 2009. We examine whether identified Research Recommendations for each agent were addressed and their potential impact on resolving classification uncertainties.

METHODS

We reviewed the IARC classifications of each of the 20 priority agents and identified major new epidemiological and human mechanistic studies published since the last evaluation. Information sources were either the published Monograph for agents that have been reevaluated or, for agents not yet reevaluated, Advisory Group reports and literature searches. Findings are described in view of recent methodological developments in Monographs evidence evaluation processes.

DISCUSSION

The majority of the 20 priority agents were reevaluated by IARC since 2009. The overall carcinogen classifications of 9 agents advanced, and new cancer sites with either "sufficient" or "limited" evidence of carcinogenicity were also identified for 9 agents. Examination of published findings revealed whether evidence gaps and Research Recommendations have been addressed and highlighted remaining uncertainties. During the past decade, new research addressed a range of the 2009 recommendations and supported updated classifications for priority agents. This supports future efforts to systematically apply findings of Monograph reviews to identify research gaps and priorities relevant to evaluation criteria established in the updated IARC Monograph Preamble. https://doi.org/10.1289/EHP12547.

Quantification of Ochratoxin A in 90 spice and herb samples using the ELISA method

This study addressed the challenge of accurately detecting mycotoxins in herbs and spices, which have gained popularity as alternative medicines but pose health risks due to potential contamination. We used a competitive direct ELISA kit (Art No. 8610), Veratox for Ochratoxin, to quantify Ochratoxin A in the herb and spice samples. The samples were first prepared using solid-liquid extraction with 70% methanol. The resulting filtrate was then subjected to ELISA analysis. The results of the analysis were then further analyzed using principal component analysis (PCA). In this study, PCA was used to classify the concentration levels of Ochratoxin A based on various factors, such as the packaging type, country of origin, shelf life, and sample weight. The limits of detection (LOD) and quantification (LOQ) values indicate the lowest amount of Ochratoxin A that can be detected and quantified, respectively, with high accuracy and precision. The range of the LOD and LOQ values (0.43-0.58 µg/kg and 1.45-1.95 µg/kg, respectively) suggests that the method used was capable of detecting and quantifying Ochratoxin A in the herb and spice samples at different concentrations with a high degree of accuracy and precision. These results suggest that while most of the samples (73.33%) were below the maximum residue limit (MRL) for Ochratoxin A, a significant number of samples (26.67%) had concentrations of Ochratoxin A that were higher than the MRL. This highlights the importance of monitoring Ochratoxin A in herb and spice samples and ensuring the products are safe for consumption.

Occupational exposure to nanomaterials and biomarkers in exhaled air and urine: Insights from the NanoExplore international cohort

The current evidence on nanomaterial toxicity is mostly derived from experimental studies making it challenging to translate it into human health risks. We established an international cohort (N = 141 workers) within the EU-LIFE project "NanoExplore" to address possible health effects from occupational exposures to nanomaterials. We used a handheld direct-reading optical particle counter to measure airborne nanoparticle number concentrations (PNC) and lung-deposited surface areas (LDSAs). Airborne particles were characterized by TEM and SEM-EDAX. We assessed oxidative/nitrosative stress with a panel of biomarkers in exhaled breath condensate (EBC) (8-isoprostane, malondialdehyde, nitrotyrosine), inflammation (high-sensitivity C reactive protein (hs-CRP), IL-1β, TNF-α, IL-10) and KL-6 (considered as biomarker of interstitial lung fibrosis) and urine (total antioxidant power (TAP), 8-isoprostane, and malondialdehyde). Exhaled breath sampled in gas-sampling bags were assessed for oxidative potential. These biomarkers were quantified pre-shift at the beginning of the workweek and post-shift the 4th day. Relationships between airborne nanoparticle concentration and biomarkers were assessed by multiple linear regression with log-transformed exposure and biomarker concentrations adjusted for potential confounders. We found a positive dose-response relationship for three inflammation biomarkers (IL-10, IL-1β and TNF-α) in EBC with both PNC and LDSA. A negative dose-response relationship was observed between PNC and TAP. This study suggests that occupational exposures to nanoparticles can affect the oxidative balance and the innate immunity in occupationally exposed workers. However, owing to the intrinsic variability of biomarkers, the observed changes along with their health significance should be assessed in a long-term perspective study.

Healthy Bus Drivers, Sustainable Public Transport: A Three-Time Repeated Cross-Sectional Study in Switzerland

Objectives: To study the change in the prevalence of bus drivers' health outcomes between 2010 and 2022 and their relationship with working conditions. Method: Unionized bus drivers completed a self-administered questionnaire in 2010, 2018, and 2022 on 13 health outcomes, sick leaves, and accidents and working conditions and their change during SARS-CoV-2 crisis. For outcomes which prevalence increased since 2010, we performed logistic regression models adjusted for covariates. Results: The study sample included 772 participants in 2010, 393 in 2018, and 916 in 2022. The most prevalent health problem (≥50%) was shoulder or neck muscle pain. The most tedious working conditions were working days over 10 h. Shoulder or neck pain, sleep disorders, sick leaves, and accidents increased since 2010 and were associated with working conditions, and co-morbidity. The SARS-CoV-2 pandemic had additional negative consequences. Conclusion: Most bus drivers' working and health conditions worsened in the last 12 years. Given the study design, the results deserve a cautious interpretation and generalization. Cohort studies should confirm these results and inform interventions targeting the most tedious and harmful working conditions.

The carcinogenicity of opium consumption: a systematic review and meta-analysis

The carcinogenicity of opium consumption was recently evaluated by a Working Group convened by the International Agency for Research on Cancer (IARC). We supplement the recent IARC evaluation by conducting an extended systematic review as well as a quantitative meta-analytic assessment of the role of opium consumption and risk for selected cancers, evaluating in detail various aspects of study quality on meta-analytic findings. We searched the published literature to identify all relevant studies on opium consumption and risk of selected cancers in humans through 31 October, 2022. Meta-relative risks (mRRs) and associated 95% confidence intervals (CIs) were estimated using random-effects models for studies of cancer of the urinary bladder, larynx, lung, oesophagus, pancreas, and stomach. Heterogeneity among studies was assessed using the I2 statistic. We assessed study quality and conducted sensitivity analyses to evaluate the impact of potential reverse causation, protopathic bias, selection bias, information bias, and confounding. In total, 2 prospective cohort studies and 33 case-control studies were included. The overall pooled mRR estimated for 'ever or regular' versus 'never' use of opium ranged from 1.50 (95% CI 1.13-1.99, I2 = 0%, 6 studies) for oesophageal cancer to 7.97 (95% CI 4.79-13.3, I2 = 62%, 7 studies) for laryngeal cancer. Analyses of cumulative opium exposure suggested greater risk of cancer associated with higher opium consumption. Findings were robust in sensitivity analyses excluding studies prone to potential methodological sources of biases and confounding. Findings support an adverse association between opium consumption and cancers of the urinary bladder, larynx, lung, oesophagus, pancreas and stomach.