Some of the toxic chemicals included in Scorecard are
actually classes of related chemicals (e.g., arsenic
compounds or polychlorinated biphenyls). Other Scorecard
chemicals are members of classes (e.g., lead nitrate is a
member of the class of lead compounds). Scorecard indicates
whether substances are classes or members of classes in the
Links section of every Chemical Profile. Tracking the class
and member status of toxic substances is important for
correctly identifying chemical hazards.
Scorecard's authoritative source for identifying recognized
health hazards is Proposition 65. Like most hazard
identification references, Proposition 65 identifies both
chemical classes and specific members as recognized
carcinogens, developmental and reproductive toxicants. For
example, cadmium and cadmium compounds are identified as
carcinogens. This hazard identification extends to all
members of the class of cadmium compounds, although a
detailed listing of specific cadmium compounds is not
To ensure that all members of classes that are recognized
hazards inherit the identification assigned to their class,
Scorecard is programmed to utilize the following decision
1) If a class has been assigned a recognized health effect,
all members of that class should also be assigned that
recognized health effect. Recognized -> recognized hazard
identification inheritance is transferred down through all
intervening subclasses to all constituent members.
In some cases, Proposition 65 identifies the health hazards
of specific members of a class of compounds, but is silent
about the class. To determine the type of hazard that
should be assigned to a class based on its members,
Scorecard utilizes the following decision rules:
2) If all members of a class have been assigned a recognized
health effect, that class should be assigned that recognized
3) If any member of a class has been assigned a recognized
health effect, that class should be assigned that suspect
health effect. Recognized->Suspect hazard identification
inheritance is transferred up through all intervening
subclasses to the most inclusive class.
P65-MC is the reference citation provided for any chemical
with hazard identification based on these rules.
In many cases, suspect health hazards have been identified
for chemicals that are classes or members. Because these
hazard identifications are more uncertain than the
authoritative determinations made under Proposition 65, it
was considered inappropriate to assume all members of a
class should inherit a suspect health effect assigned to
that class. Scorecard also does not transfer suspect health
hazards to a class from a member (even if there is
consistency in suspect health effects across members).
Note that these decision rules are very strict about when it
is appropriate to assign member hazard identifications to a
class. This is done to preserve the scientific
defensibility of Environmental Defense's hazard identification project.
Users are encouraged to examine the suspect health effects
assigned to classes and members via the Links section of
Chemical Profiles. Even if a certain health effect is not directly associated with a TRI category like diisocyanates (EDF-067), for example, it is possible to examine the profiles of
members of this class and learn that several are suspect
immunotoxicants and skin and sense organ toxicants.