A small number of Toxic Release Inventory chemicals have not
been assigned human health hazard identifications based on
Environmental Defense's review of scientific and regulatory literature and
analysis of toxicological databases. Environmental Defense conducted a
customized, supplementary review of TRI compounds with
reported environmental releases to identify any remaining
potential human health hazards. We determined that there
were three potential explanations for why a substance listed
under TRI might be missing a human health hazard
identification:
1) TRI lists a category or class of compounds, rather than a
specific chemical that has been the subject of toxicity
evaluations. For example, the TRI category of "certain
glycol ethers" has not specifically been the subject of
hazard identification efforts, although many glycol ethers
covered by this category have been characterized as human
health hazards. Since the class of glycol ethers includes
recognized developmental and reproductive toxicants, the TRI
category can be considered suspect for these health effects.
Environmental Defense's Member Class
documentation explains how and when Scorecard assigns
classes of compounds hazards based on their constituent
members. In some cases, TRI categories are not known to
contain recognized hazards, although constituent members may
be suspected of harming human health. Since Scorecard does
not designate a class as suspect based on members
being suspect, these TRI categories do not have any
identified health effects.
2) No toxicological data are readily available that
characterize the potential human health effects of a TRI
chemical. Environmental Defense widened its search for hazard identification
data for all TRI chemicals that are not assigned health
effects in Scorecard. We examined sources that were not
generally relied on for hazard identification because they
do not support abstracting hazard classifications for large
numbers of chemicals. Many references do not utilize
consistent hazard descriptors or summarize hazard
identification evaluations in tables, so they could not be
utilized as a hazard identification source without chemical-
by-chemical review. "Last resort" source of hazard
identification include several US EPA databases: Integrated
Risk Information System (IRIS), Health Effects Assessment
Summary Tables (HEAST) and Office of Pesticide Programs
Databases (OPP). Last-resort sources also include the
California Air Resources Board's Toxic Air Contaminant
Identification Summaries (TAC), and factsheets and material
safety data sheets available on the internet.
3) The TRI chemical is an environmental hazard, but not a
human health hazard. For example, several
chlorofluorocarbons (CFCs) do not directly pose human health
risks, but are listed under TRI because of their capacity to
deplete the stratospheric ozone layer. On the basis of
available data, such chemicals do not appear to pose direct
human health risks.
The following CFC chemicals with substantial reported
environmental releases have not been assigned human health
effects:
2-chloro-1,1,1-trifluorethane (75-88-7)
1,1,1-trifluoro-2,2-dichloroethane (306-83-2)
1-chloro-1,1,2,2-tetrafluoroethane (354-25-6)
2-chloro-1,1,1,2-tetrafluoroethane (2837-89-0)
1,2-dichloro-1,1,2-trifluoroethane (354-23-4)
