Formaldehyde might be a key risk factor for the rise in asthma cases
Formaldehyde has been classified as a known human carcinogen (cancer-causing substance) by the International Agency for Research on Cancer and as a probable human carcinogen by the U.S. Environmental Protection Agency. Research studies of workers exposed to formaldehyde have suggested an association between formaldehyde exposure and several cancers, including nasopharyngeal cancer and leukemia
There was little evidence for any association between pesticides/herbicide exposure and ALS. In contrast, evidence was found, suggesting an increased risk of ALS with formaldehyde exposure. Because of the longitudinal design, this result is unlikely to be due to bias, but it should nevertheless be interpreted cautiously and needs to be verified independently.