Dichloroacetic acid

Additional toxicological data

Administrative data

Endpoint:

additional toxicological information

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Publication peer reviewed

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Materials and methods

Type of study / information:

Adducts

Test material

Test material information

Constituent 1

Reference substance name:

Dichloroacetic acid

EC Number:

201-207-0

EC Name:

Dichloroacetic acid

Cas Number:

79-43-6

Molecular formula:

C2H2Cl2O2

IUPAC Name:

2,2-dichloroacetic acid

Details on test material:

- Name of test material (as cited in study report):

Results and discussion

Any other information on results incl. tables

Formation of hemoglobin and albumin-adducts, in which the rat had a larger amount of adducts than the mouse.

Applicant's summary and conclusion

Conclusions:

DCA (dichloroacetate) formed hemoglobin and albumin adducts. Portions of this binding was also due to metabolic incorporation.

Executive summary:

Adducts to macromolecules from trichloroethylene formed by in vivo and in vitro metabolism have been reported by many investigators. We examined the in vivo adduction of the blood proteins hemoglobin (Hb) and albumin in rats and mice dosed orally with [¹⁴C]trichloroethylene ([¹⁴C]TRI) to explore the development of a protein adduct biomarker of TRI exposure. We also examined the adduction of these two proteins from doses of [¹⁴C]trichloroacetate (TCA) and [¹⁴C]dichloroacetate (DCA), two metabolites of TRI. Association of label with albumin peaked at 4-8 hr in the rat (2480 nmol eq TRI/mg protein) and 2-4 hr in the mouse (1580 nmol eq TRI/mg protein). The decay was exponential with a half-life consistent with that of rat or mouse albumin (approx 24 hr). The time course of label with Hb was characterized by an early plateau at 8 hr in rat (28 nmol eq TRI/mg protein), 4 hr in mouse (7 nmol eq TRI/mg protein), and followed by a slow steady increase, peaking at 120 hr (54 nmol eq TRI/mg protein, rat; 38 nmol eq TRI/mg protein, mouse). This apparent binding was linear with dose in the rat, but was convex in the mouse albumin (mouse Hb label was below detection at low dose). We also found that a portion of the irreversibly associated label, referred to by previous investigators as "binding," could be accounted for as metabolic incorporation of label into glycine and serine. The fraction accounted for by metabolic incorporation was constant in albumin.(approximately 2/3), while in Hb, this portion was time dependent, approximately 30% at the early sampling time, 75% at the late time, implying the observed late increase could be accounted for by metabolic incorporation. TCA and DCA also formed Hb and albumin adducts. Portions of this binding was also due to metabolic incorporation. The pattern of the binding from TCA in albumin was different from that of TRI, implying a route to adduct from TRI which does not proceed through TCA.