PROGRAMS AND PLANS--Dyes for Water Tracers
In Reply Refer To: July 21, 1986
WGS-Mail Stop 415
OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 86.08
Subject: PROGRAMS AND PLANS--Dyes for Water Tracers
Surface Water Branch Technical Memorandum 81.05 provided a statement from the
Environmental Protection Agency (EPA) that EPA would not object to the use of
rhodamine WT dye as a tracer in lieu of additional information on human toxi-
cology or a change in the position of the Food and Drug Administration.
A 1982 paper by S. L. Abidi (U.S. Fish and Wildlife Service, National Fishery
Research Laboratory, La Crosse, Wisconsin) showed that diethylnitrosamine
(DENA), a recognized carcinogen, can be formed under laboratory conditions
when rhodamine WT dye is added to nitrite-rich water.
An advance copy of a paper by T. R. Steinheimer and S. M. Johnson was dis-
tributed with Water Resources Division Memorandum 85.82. This report has
since been published in Water-Supply Paper 2290 (1986, pages 37-49). This
paper showed that nitrosamine (NDEA) formation didnotoccur in nitrite-
enriched river-water samples injected with rhodamine WT at concentrations
typically used in the field. It also was determined that the rate of photo-
chemical decomposition of NDEA in the presence of dissolved oxygen and nitrite
at environmental levels is approximately the same as its rate of formation
from the dye, so NDEA becomes a transient species with a very short half
life in river water. Steinheimer's and Johnson's analysis also did_not
detect_NDEA in any samples tested from four rivers where rhodamine WT was
injected in water known to contain nitrite.
Attached for your information are two letters from Crompton and Knowles
Corporation, the manufacturer of rhodamine WT, one of which includes a risk-
assessment report to evaluate the potential risk associated with the genera-
tion of DENA as a result of the use of rhodamine WT. Also attached is a copy
of a report by P. L. Smart entitled "A Review of the Toxicity of Twelve
Fluorescent Dyes Used for Water Tracing."
The letter dated October 28, 1982, from Crompton and Knowles Corporation
supports the work of Steinheimer and Johnson in showing that DENA degrades
rapidly in water by photolysis and that DENA which may result from the use of
rhodamine WT would be transient.
The letter dated September 27, 1983, from Crompton and Knowles Corporation
shows that the risk associated with a typical use of rhodamine WT is expected
to be several orders of magnitude less than the risk believed to be acceptable
to EPA.
OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 86.08 2
The report by P. L. Smart provides information on the toxicities of some dyes
used in the U.S. Geological Survey for water tracing. The most commonly used
water-tracing dye, rhodamine WT, couldnotbe demonstrated to provide either
a carcinogenic or mutagenic hazard. The author states that, "Based on the
experimental results reviewed . . ., there is no evidence of either a short
or long-term toxic hazard to dye users or those drinking water containing
tracer dyes." However, he also points out that rhodamine WT is a severe
irritant to the eyes and is moderately irritating to the skin. He therefore
recommends that all personnel handling dyes should wear protective gloves and
clothing and that all skin areas contaminated by dye be washed immediately
with soap and water and that any splashes in the eye be flushed with copious
quantities of water.
Based on the above-summarized information, the policy concerning concentra-
tions at intakes, as specified in Water Resources Division Memorandum 66.90,
is still in effect. In that memorandum, the policy specifically referred to
the use of rhodamine B. The statement has since been extended to the use of
rhodamine WT (Wilson and others, 1984, page 11). The pertinent policy state-
ment is that 10 ppb (parts per billion is equivalent to micrograms per liter)
shall be the maximum allowable concentration passing any water intake that
ultimately results in direct or indirect human consumption.
It also is recommended that rubber or plastic gloves be worn when handling
concentrated dye solutions. When the dye does come into contact with the
skin, it should be washed off immediately. If dye gets into an eye, the
eye should be immediately and thoroughly flushed with water. Also, pipetting
of dye solutions should be done with a squeeze bulb or by using a long piece
of flexible tubing to prevent accidental ingestion of the dye (Wilson and
others, 1984, page 11).
Reference: Wilson, James E., Jr., Cobb, Ernest D., and Kilpatrick, Frederick A.,
1984, Fluorometric procedures for dye tracing: U.S. Geological Survey Open-
File Report 84-234, 53 pages (to be printed as U.S. Geological Survey Techniques
of Water-Resources Investigations, Book 3, Chapter A12, revised).
Verne R. Schneider
Chief, Office of Surface Water
3 Attachments
WRD Distribution: A, B, S, FO, PO, SL
This memorandum supersedes WRD memoranda 66.90 and 85.82 and SWB memorandum 81.05.