Merging Redundant Columns

I'm doing up a database of hazardous chemicals, based on publicly available information from various agencies. Each chemical has a name and a number, and has different hazards associated to it. The hazards are grouped into classes, and for each class the hazard is further broken down into categories. Hence for an explosive hazard (the class) I could have categories 1, 2 and 3 based on severity. For each iteration of the hazard class and category (for example explosive hazard category 1), there is a non-unique hazard statement. Another complication is that there is a qualitative element in the classification system, and hence agencies from different countries could classify the same chemical differently. This should be captured into the database as well. Thus for every chemical, I will have to enter the Japanese classification, the EU classification, etc.

I've managed to set up what I think is a correct relationship, based on my understanding of databases. However when I generate the report, fields such as the chemical name and ID are repeated for each hazard. I would like to merge these redundant entries, so the chemical name, I.D., and any other repeated fields appear only once. In essence, I'm trying to make it such that there is only one entry for each chemical+I.D/country, with multiple hazard subentries, rather than having multiple, seemingly duplicate entries.