The only concern I saw in their documentation was of a release of the TDI from leaks in tanks, pipes or accidental release during delivery of the TDI. There was no concern over by-products release, and no reports of accidents over the last five years.Toluene diisocyanate (TDI) is converted to a less toxic material called prepolymer by reacting the TDI with a polyester polyol resin (polyol) within 24 hours of delivery. The use of the just-in-time inventory practice is intended, in part, to minimize the amount of TDI and TDI-bearing resins present on the premises and minimize the period of time that TDI is present on-site to reduce the risk of a release. During batch processing, the exothermic reaction between TDI and polyol releases heat that raises the batch temperature to a design temperature of 140. This temperature is maintained for 16-20 hours by continuous injection of polyol. Once the reaction is complete, the prepolymer is allowed to cool to and is then transferred to Tank 62 for storage. As needed, the prepolymer is pumped from Tank 62 to the weighing and mixing station where it is mixed with additional polyols and poured into molds to form polyurethane foam surfboard blanks.
http://www.rtknet.org/rmp/sum7/CA/fac100000087078
Also, there is some info on TDI effects on humans (the only one cited is chronic lung function decline), and its non carcinogenic.
http://www.epa.gov/iris/subst/0503.htm