A Putative Adverse Outcome Pathway Relevant to Carcinogenicity Induced by Sulfuric Acid in Strong Inorganic Acid Mists

Tobacco and alcohol use are the risk factors responsible for the greatest burden of head and neck cancers: a study from the Global Burden of Disease Study 2019

BACKGROUND

The risk factors associated with cancers of the larynx, nasopharynx, lips, and oral cavity, as well as other pharyngeal cancers, share many similarities. To better understand how these risk factors manifest differently across various head and neck tumor types, we utilized data from the GBD database to conduct an in-depth analysis.

METHODS

Our study employed the 2019 GBD dataset to scrutinize trends in incidence, mortality, and DALYs related to these cancers. This analysis covered the period from 1990 to 2019 and was stratified by sex, age, geographical region, and the socio-demographic index.

FINDINGS

In 2019, lip and oral cavity cancers were found to have the highest incidence rates, with notably higher ASIRs observed in males compared to females. Interestingly, the ASIRs for laryngeal cancer showed a decreasing trend over the studied time frame from 1990 to 2019. Our findings revealed that smoking posed a significantly greater risk for laryngeal and lip and oral cavity cancers, whereas alcohol consumption was more strongly linked to NPC. Central Europe exhibited the ASDR for laryngeal cancer. For lip and oral cavity cancer, the impact of tobacco chewing on female ASDR was most pronounced in South Asia. In contrast, nasopharyngeal cancer had its highest ASDR in Asia.

CONCLUSION

Our investigation underscores that smoking and alcohol consumption are leading risk factors for cancers of the head and neck, although their effects vary depending on the specific type of cancer, the sex of the patient, age group, and regional demographics. While occupational exposure to carcinogenic substances does not appear to be a predominant factor, it remains an important consideration that should not be overlooked in the comprehensive assessment of risk for these malignancies.

Strong inorganic acid mists and respiratory tract cancers: a meta-analysis

BACKGROUND

Exposure to strong inorganic acid mists (SIAMs) in the workplace has been linked to respiratory tract cancers.

AIMS

We conducted a meta-analysis of cohort and case-control studies examining the association between occupational SIAMs and respiratory tract cancers other than laryngeal cancer, which is already established.

METHODS

Studies mentioned in the 1992 IARC Monograph on carcinogenicity of SIAMs were combined with later studies identified from a systematic search of Scopus, PubMed and Embase. Forest plots of relative risks (RR) and odds ratios were constructed for the 34 identified studies. A random-effects model was used to address heterogeneity.

RESULTS

An association between the roles associated with occupational SIAMs exposure and risk of lung (RR = 1.17; 95% confidence interval [CI] = 1.05-1.32), and nasal cancers (RR = 3.30, 95% CI = 1.16-9.41) was found. The risk of oral and pharyngeal cancer was also associated with SIAMs exposure-related roles (RR = 1.59, 95% CI = 0.98-2.57). Results did not differ by study design, gender or outcome for all three cancers. A positive association for lung cancer was found with chemical (RR = 1.25, 95% CI = 1.13-1.38), and metal and steel industries (RR = 1.19, 95% CI = 1.04-1.37), as well as for oral and pharyngeal cancer with chemical industry (RR = 1.72, 95% CI = 1.57-1.89). We checked publication bias for lung (p = 0.35), oral and pharyngeal (p = 0.02) and nasal cancer (p = 0.40).

CONCLUSIONS

Our study showed an association between occupational SIAM exposure and risk of lung, nasal, and possibly oral and pharyngeal cancers. However, weaknesses in the recording of confounding and exposure data in the currently available literature were found.

Sulfuric acid-induced skin neoplasms in immunocompetent mice

This study investigates the carcinogenic potential of chronic dermal exposure (16 weeks) to sulfuric acid (SA) in immunocompetent mice. Clinical assessments, histopathological analyses, immunohistochemical analyses and biochemical assays were conducted to evaluate skin irritation, oxidative stress biomarkers and the potential carcinogenic effect of SA. Results indicated that prolonged exposure to SA leads to various alterations in skin structure, notably inflammation, preneoplastic and neoplastic proliferation in hair follicles, as well as hyperkeratosis and acanthosis, resulting in an increased epidermal thickness of 98.50 ± 21.6 μm. Immunohistochemistry analysis further corroborates these observations, showcasing elevated nuclear expression of p53 and Ki-67, with a significant mitotic index of (57.5% ± 2.5%). Moreover, biochemical analyses demonstrate that SA induces lipid peroxidation in the skin, evidenced by a high level of Malondialdehyde and a consequential reduction in catalase activity. These findings suggest that prolonged exposure to SA can induce skin neoplasms, highlighting the need for stringent safety measures in environments where SA is frequently used. This study underscores the potential occupational health risks associated with SA exposure.

Atmospheric Dispersion of Gaseous Amine Emitted from Absorption-Based Carbon Capture Plants in Saskatchewan, Canada

Carbon capture and storage (CCS) is a key strategy to reduce carbon dioxide (CO2) emissions from industrial point sources. Gas absorption into aqueous amine solutions is an immediate technology for carbon capture that has been tested in many demonstration plants. One concern of using the amine-based carbon capture process is the environmental impacts and health risk caused by emissions of gaseous amines from the process to the atmosphere. This work applied the knowledge of air dispersion modelling to map out the atmospheric dispersion and resulting ground surface level concentration of gaseous amine, namely Monoethanolamine (MEA), from a coal-fired power plant (with a carbon capture unit) and in surrounding areas, in case of an accidental leaking of amine from the CCS system to the atmosphere. The chosen study area was centered on a coal-fired power plant in the province of Saskatchewan, Canada. The Environmental Protection (EPA) approved air pollution model (CALPUFF), together with meteorological and geophysical data were used for gaseous amine dispersion simulation. The results were presented, and the ground amine concentrations were found to vary with wind patterns (wind direction and wind speed). The maximum ground surface amine concentrations standard is 15.2 µg/m3. However, the results showed that when using the water wash unit, the MEA concentrations were well below the standard level, compared to those without the water wash unit. It is essential for CO2 capture plants located in highly populated areas to be equipped with water wash units.

Life cycle assessment of environmental impacts associated with oxidative desulfurization of diesel fuels catalyzed by metal-free reduced graphene oxide

This study aimed to analyze the environmental impacts of the oxidative desulfurization (ODS) process catalyzed by metal-free reduced graphene oxide (rGO) through life cycle assessment (LCA). The environmental impacts study containing the rGO production process, the ODS process, the comparison of different oxidants and solvents was developed. This study was performed by using ReCiPe 2016 V1.03 Hierarchist midpoint as well as endpoint approach and SimaPro software. For the production of 1 kg rGO, the results showed that hydrochloric acid (washing), sulfuric acid (mixing), hydrazine (reduction) and electricity were four main contributors in this process, and this process showed a significant impact on human health 14.21 Pt followed by ecosystem 0.845 Pt and resources 0.164 Pt. For the production of 1 kg desulfurized oil (400 ppm), main environmental impacts were terrestrial ecotoxicity (43.256 kg 1,4-DCB), global warming (41.058 kg CO₂), human non-carcinogenic toxicity (19.570 kg 1,4-DCB) and fossil resource scarcity (13.178 kg oil), and the main contributors were electricity, diesel oil and acetonitrile. The whole ODS process also showed a greatest effect on human health. For two common oxidants hydrogen peroxide and oxygen used in ODS, hydrogen peroxide showed a greater impact than oxygen. On the other hand, for three common solvents employed in ODS, N-methyl-2-pyrrolidone had a more serious impact on human health followed by acetonitrile and N,N-dimethylformamide. As such, LCA results demonstrated the detailed environmental impacts originated from the catalytic ODS, hence elucidating systematic guidance for its future development toward practicality.

Application of Standardized Proportional Mortality Ratio to the Assessment of Health Risk in Relatively Healthy Populations: Using a Study of Cancer Risk in Telecommunication Workers with Excess Exposure to Acid Mists as an Example

When a study population is relatively healthy, such as an occupational population, epidemiological studies are likely to underestimate risk. We used a case study on the cancer risk of workers with exposure to acid mists, a well-documented carcinogen, to demonstrate that using proportional mortality ratios (PMRs) is more appropriate than mortality ratios in assessing risk in terms of mortality. The study included 10,229 employees of a telecommunication company who worked in buildings with battery rooms. In these buildings, the battery rooms had the highest levels of sulfuric acid in the air (geometric mean = 10.7 μg/m3). With the general population in Taiwan as a reference, a decreased standardized mortality ratio (0.42, p < 0.01) from all causes combined, between 1 January 1985 and 31 December 1996, was observed, indicating a healthy worker effect. When we reanalyzed the data using standardized PMR, elevated risks were observed for all cancers combined (1.46, p = 0.01) and cancers of the digestive organs and peritoneum (1.61, p = 0.02), especially stomach cancer (2.94, p = 0.01). The results showed that PMR can detect increases in mortality when a study population is generally healthier than the comparison population and call for further studies on the possible carcinogenic effects of low-level acid mist exposures on the stomach.

A pragmatic approach to Adverse Outcome Pathway (AOP) development and evaluation

The adverse outcome pathway (AOP) framework provides a practical means for organizing scientific knowledge that can be used to infer cause-effect relationships between stressor events and toxicity outcomes in intact organisms. It has reached wide acceptance as a tool to aid chemical safety assessment and regulatory toxicology by supporting a systematic way of predicting adverse health outcomes based on accumulated mechanistic knowledge. A major challenge for broader application of the AOP concept in regulatory toxicology, however, has been developing robust AOPs to a level where they are peer reviewed and accepted. This is because the amount of work required to substantiate the modular units of a complete AOP is considerable, to the point where it can take years from start to finish. To help alleviate this bottleneck, we propose a more pragmatic approach to AOP development whereby the focus becomes on smaller blocks. First, we argue that the key event relationship (KER) should be formally recognized as the core building block of knowledge assembly within the AOP knowledge base (AOP-KB), albeit framing them within full AOPs to ensure regulatory utility. Second, we argue that KERs should be developed using systematic review approaches, but only in cases where the underlying concept does not build on what is considered canonical knowledge. In cases where knowledge is considered canonical, rigorous systematic review approaches should not be required. It is our hope that these approaches will contribute to increasing the pace at which the AOP-KB is populated with AOPs with utility for chemical safety assessors and regulators.