Digitalis and blue halos around lights), convulsions, and deadly disturbances of the heart. For a case description, see the paper by Lacassie. Vincent van Gogh's "Yellow Period" may have been influenced by digitalis therapy which, at the time, was thought to control seizures. As noted above, other oculotoxic effects of digitalis include generalized blurry vision, as well as seeing a "halo" around each point of light. In some instances, people have confused digitalis with the relatively harmless comfrey ("Symphytum") plant, which is often brewed into a tea, with fatal consequences. Other fatal accidents involve children drinking the water in a vase
Chemical plant workers typically include engineers, plant operators, and maintenance technicians. Other personnel at the site could include chemists, management/administration and office workers. Types of engineers involved in operations or maintenance may include chemical process engineers, mechanical engineers for maintaining mechanical equipment, and electrical/computer engineers for electrical or computer equipment. Large quantities of fluid feedstock or product may enter or leave a plant by pipeline, railroad tank car, or tanker truck. For example, petroleum commonly comes to a refinery by pipeline. Pipelines can also carry petrochemical feedstock from a refinery to a nearby petrochemical plant. Natural gas is a product which comes