Management of Commercially Generated Radioactive Waste - U.S. ...

E.16
E.7 SPECIFIC CONSIDERATION OF HEALTH EFFECTS FROM CARBON-14
The radiological signficance of 1C has received much attention because 1) carbon
occurs everywhere in nature, including man; 2) 14 C has a long half-life, 5730 years; and
3) weapons tests have significantly increased global 14 C levels (UNSCEAR 1977, pp. 41-42).
Only recently has attention been directed to the considerably smaller 14C releases that
may be expected from the nuclear fuel cycle (ERDA 1975, Hayes 1977).
As with tritium, there is concern that transmutation effects (i.e., effects resulting
from the conversion of a carbon atom to a nitrogen atom in a vital molecule) may increase
the health risk from 14 C beyond that attributable to the beta-radiation dose. This is of
particular concern with regard to genetic effects. Direct experimental data to settle this
question are not available. In his original article (1958) calling attention to health
risks from 1C, Pauling concluded "that the special mechanism involving 1C atoms in
the genes themselves is less important than irradiation in causing genetic damage."
Totter, Zelle and Hollister (1958), reviewing the then available data, concluded that
"subject to large uncertainty, the transmutation effect of 14 C atoms contained in the
genetic material of the human body could lead to about the same number of genetic mutations
as the radiation effect from 14C."
The general problem of transmutati'on effects has received much recent study, and the
occurrence and importance of such effects has been clearly demonstrated for 32 P (Krisch
and Zelle 1969). Less work has been done with 1C, and reported results are not entirely
consistent. In studies with Drosophila (fruit flies), Lee and Sega observed little, if any,
mutagenic effect from 14 C-thymidine incorporated in sperm. They concluded that "if transmutation
of 14C is mutagenic at all, it is less effective than 32 P (in similar experi-
ments) by two orders of magnitude;" and that, "for practical purposes in considering muta-
genic hazards or toxicity effects due to chromosome breakage, only the beta radiation of
1C needs to be considered."
On the other hand, McQuade and Friedkin (1960) observed twice the frequency of chromo-
some breakage in onion root tips after administering thymidine with 1C-labeling in the
methyl group, as with 14 C-labeling in the 2 position. This seems to imply a differential
transmutation effect, since the- labeling position should not influence beta-radiation-
induced effects. There is, in any case, no experimental evidence for a transmutation effect
that is many times larger than the radiation effect, although such claims have been made on
theoretical grounds (Golenetskii et al. 1976). Therefore, based on what appears a prepon-
derance of informed opinion (Krisch and Zelle 1969, and Lee and Sega 1973), this report does
not consider the possibility of 14 C transmutation effects.