The human health impact of fiber reinforced polymer (FRP) composite materials manufactured by the pultrusion industry is not fully understood. In particular, it is unclear whether the human health impact of toxic chemicals present in low concentrations in fire retardant pultruded FRP materials is disproportionately high. This impact may be an important criterion when making boundary selection decisions in the life cycle assessment (LCA) of these materials. The North American pultrusion industry was surveyed to determine resin mix concentration levels and workplace inhalation toxicity exposure levels. LCAs were then conducted on three building panel resin mixes to determine whether the human health impact of toxic chemicals used in the mixes was low enough to exclude the chemicals from the life cycle inventory (LCI) boundary. The first resin mix represented a typical pultruded product, the second mix removed toxic chemicals present in small concentrations, and the third mix replaced toxic chemicals present in small concentrations with a nontoxic chemical. Results showed that toxicity levels fell below exposure limits and no significant difference in human health impact existed among the LCAs. The research concludes that human health impact is a useful criterion when defining an LCI boundary. Toxic chemicals present in small concentrations in pultruded FRP materials may be excluded from the LCI boundary, as their human health impacts are low. Because these levels are marginal in North American pultrusion factories, no changes in resin mixes are recommended for the pultrusion industry.