Insights from Epidemiology into Dichloromethane and Cancer Risk

Abstract

Dichloromethane (methylene chloride) is a widely used chlorinated solvent. We review the available epidemiology studies (five cohort studies, 13 case-control studies, including seven of hematopoietic cancers), focusing on specific cancer sites. There was little indication of an increased risk of lung cancer in the cohort studies (standardized mortality ratios ranging from 0.46 to 1.21). These cohorts are relatively small, and variable effects (e.g., point estimates ranging from 0.5 to 2.0) were seen for the rarer forms of cancers such as brain cancer and specific hematopoietic cancers. Three large population-based case-control studies of incident non-Hodgkin lymphoma in Europe and the United States observed odds ratios between 1.5 and 2.2 with dichloromethane exposure (ever exposed or highest category of exposure), with higher risk seen in specific subsets of disease. More limited indications of associations with brain cancer, breast cancer, and liver and biliary cancer were also seen in this collection of studies. Existing cohort studies, given their size and uneven exposure information, are unlikely to resolve questions of cancer risks and dichloromethane exposure. More promising approaches are population-based case-control studies of incident disease, and the combination of data from such studies, with robust exposure assessments that include detailed occupational information and exposure assignment based on industry-wide surveys or direct exposure measurements.

Risk of lung cancer associated with six types of chlorinated solvents: results from two case–control studies in Montreal, Canada: Table 1

“…Previous studies have not indicated an excess risk of lung cancer associated with exposure to TCE and methylene chloride 6 7 41. For methylene chloride, our results showed a null association both overall and across the various subgroup analyses.…”

Acute inhalation co‐exposure to 1,2‐dichloropropane and dichloromethane cause liver damage by inhibiting mitochondrial respiration and defense ability in mice

“…This study demonstrated the hepatotoxic effects of acute inhalation exposure to 1,2‐DCP, DCM and their combination and preliminarily clarified the relative mechanism of 1,2‐DCP and DCM‐induced liver damage. The changes in liver weight, elevated serum transaminase and pathological changes in the liver suggest that 1,2‐DCP produces hepatocellular necrosis and liver damage in mice, and our results are in agreement with previous reports (Cooper, Scott, & Bale, ; Gi et al, 2015b; Yanagiba et al, ).…”

Central nervous system tumors: a single center pathology review of 34,140 cases over 60 years

“…Lymphoma has been ranked as one of the top ten malignant tumors in this century, and it has the fastest growing incidence rate of all malignant tumors in China [27]. Despite the inherent biases, certain chemical pollutants should be carefully considered [28,29]. Germ cell tumors are also thought to be closely related to environmental factors.…”