*(1) By survey design, not all 2-digit SICs were surveyed. (2) The estimates for each 2-digit SIC apply only to the 3- and 4-digit SICs surveyed within the 2-digit SIC. Not all SICs were surveyed. (3) When using the estimates, standard errors associated with estimates should be considered. (4) Potential exposures to a chemical agent are categorized as actual (i.e., the surveyor observed the use of the specific agent) or tradename (i.e., the surveyor observed the use of a tradename product known to contain the specific agent). The estimates presented in the table combine both categories.