industrial parks. Products can be transported to their final place of use by truck, rail, pipeline, or other means in both large and small quantities.

To identify the vulnerabilities posed to the nation to terrorist attack on or other catastrophic loss in the nation’s chemical infrastructure, it is necessary first to somehow succinctly characterize this large and varied sector. This is done below in two steps: (1) a scheme for categorizing the vast number of chemicals produced by the sector and defining these categories and (2) a general model describing the sector’s supply chain.

Virtually all chemical manufacturing, storage, and use in the United States fits into one of the following categories:

• Petrochemicals and fossil fuels

• Inorganic chemicals including fertilizers

• Industrial gases

• Specialty chemicals

• Pharmaceuticals

• Consumer products.²

A description of each of these categories, including a generalized discussion of the manufacture, transport, and use of the chemicals within that category, is given below:

This category entails chemicals produced from hydrocarbon feedstocks, such as crude oil products and natural gas. It includes such chemicals as hydrocarbons and industrial chemicals (e.g., alcohols, acrylates, acetates), aromatics (e.g., benzene, toluene, xylenes), and olefins (e.g., ethylene, propylene, butadiene, methanol).

Manufacture and Use. Most of these chemicals are produced and sold in large volumes—so-called commodity chemicals—and most can be pro-