WEST READING (AP) – Last week’s fatal blast at the R.M. Palmer factory in West Reading, Berks County highlighted the combustibility of food plants in general and chocolate making in particular. Local, state, and federal investigations are ongoing as they try to pinpoint the origin and cause. Federal officials said they were investigating the role of a natural gas pipeline in the explosion. Experts say commercial ovens and furnaces, commercial refrigerant using ammonia, and combustible dust are primary explosive hazards at food plants. At least two workplace accidents happened at Palmer since 2018, according to federal records. OSHA visited the West Reading plant in 2018, when an employee lost the tip of a finger while cleaning a pressurized valve. In 2019, OSHA investigated an accident at Palmer’s plant in nearby Wyomissing, when a conveyor belt was turned on while a worker was cleaning a roller. And in January, records show, OSHA levied a penalty of more than $12,000 after an inspection at the Wyomissing plant. Details of that case were not available.