Can exposure to industrial solvents (e.g. chemicals used in manufacturing) increase the risk of developing gastric (stomach) cancer?

Industrial Solvents and Gastric Cancer Risk

There is limited evidence suggesting that exposure to certain industrial solvents may increase the risk of gastric cancer, particularly for those working in specific industries such as organic chemical manufacturing, inorganic chemical manufacturing, and surface treatment using organic solvents.

Evidence Overview

The relationship between industrial solvent exposure and gastric cancer has been investigated in several epidemiological studies with mixed results. While no definitive causal relationship has been established across all industrial solvents, certain specific exposures and industries show concerning associations.

Specific Industrial Sectors with Increased Risk

Research indicates elevated gastric cancer risk in workers from specific industrial sectors:

• Organic chemical industry: 3.51-fold increased risk (95% CI: 1.42-8.69) for those living within 2 km 1
• Inorganic chemical industry: 3.33-fold increased risk (95% CI: 1.12-9.85) within 2 km 1
• Surface treatment using organic solvents: 3.59-fold increased risk (95% CI: 1.40-9.22) within 3 km 1
• Metal industry: 46% excess gastric cancer risk (OR: 1.46; 95% CI: 1.10-1.94), increasing to 65% (OR: 1.65; 95% CI: 1.17-2.32) for those with >10 years in the industry 2

Specific Solvents and Chemicals

Some specific solvents and chemicals have shown associations with gastric cancer:

• Phenoxyacetic acids (herbicides): 70% increased risk (OR: 1.70; 95% CI: 1.16-2.48) 2
• Industries releasing nonylphenol: 6.43-fold increased risk (95% CI: 2.30-17.97) within 3 km 1
• Industries releasing antimony: 4.82-fold increased risk (95% CI: 1.94-12.01) within 3 km 1

A Montreal case-control study identified several potential occupational exposures associated with gastric cancer, including:

• Crystalline silica
• Leaded gasoline
• Grain dust
• Lead dust
• Zinc dust
• Hydraulic fluids
• Glycol ethers 3

Limitations and Considerations

It's important to note several limitations in the current evidence:

1. Mixed exposures: Many workers are exposed to multiple chemicals simultaneously, making it difficult to identify specific causative agents 4

2. Confounding factors: Studies must account for other known risk factors for gastric cancer, including:

   • Helicobacter pylori infection
   • Smoking
   • Diet
   • Body mass index 2

3. Limited research focus: While some solvents like trichloroethylene (TCE) have been extensively studied for liver and kidney cancers, their association with gastric cancer specifically has received less attention 5

Clinical Implications

For patients with a history of occupational exposure to industrial solvents:

1. Risk assessment: Evaluate the specific industry, duration of exposure, and particular solvents involved

2. Screening considerations: Consider earlier or more frequent gastric cancer screening for patients with:

   • Long-term employment (>10 years) in high-risk industries (metal, chemical manufacturing)
   • Direct exposure to phenoxyacetic acids or other implicated chemicals
   • Multiple risk factors (occupational exposure plus H. pylori infection)

3. Synergistic effects: Be aware of potential multiplicative effects with other risk factors. For example, the combined risk of H. pylori infection and phenoxyacetic acid exposure showed a multiplicative effect (OR: 3.42; 95% CI: 1.41-8.26) 2

Conclusion

While the evidence doesn't support a broad conclusion that all industrial solvents cause gastric cancer, specific exposures in certain industries appear to increase risk. The strongest associations are seen with employment in chemical industries, metal work, and exposure to certain herbicides like phenoxyacetic acids. Patients with significant occupational exposure histories should be evaluated for appropriate gastric cancer screening based on their specific exposure profile and other risk factors.