8100

• UCREFRP Catalog Number: 8100
• Author: American Fisheries Society.
• Title: Proceedings of the 22nd Annual Meeting, Colorado - Wyoming Chapter, American Fisheries Society.
• USFW Year: 1987.
• USFW - Doc Type: March 11-12, 1987.
• Copyright Material: NO

very effective control of external protozoan parasites.

F or several years now, mal ach ite green has been regarded as a potent i a 1
hazard to human health. Since 1958, various researchers in several different
countries have found that malachite green is carcinogenic, teratogenic,
mutagenic, or causes fractures in chromosomes or reduced fertility in organisms
as diverse as insects, fish, rats and rabbits (Meyer and Jorgenson 1983). It
should be noted, however, that in many of these studies, the dosage levels used
were up to 1,000 times those levels normally used in fish culture. Also, some
test animals were force-fed (galvaged) high doses of the chemical. In one study,
rabbits were dosed orally with aqueous solutions of malachite green. If the
rabbits coughed-up and accidently aspirated malachite green into the lungs, they
died within minutes of acute pulmonary toxicity. Developmental anomal ies in
surviving rabbit progeny were similar to those caused by thalidomide, a know
teratogen used as the positive control. Physical defects occurred in both
skeletal and visceral tissues (Meyer and Jorgenson 1983).

So, malachite green does pose a potential h~alth problem to human handlers
of the chemical. It is highly unlikely that the compound will ever become an FDA
registered or approved product.

The good news is that throughout the long use of malachite green in fish
culture (about 54 years now), there have been no recognized cases of accidental
human poisoning or other associated human health problems (Nelson 1974, as cited
in Meyer and Jorgenson 1983).

Today, with few exceptions, it is illegal to use malachite green in fish
culture. The USFWS has a special use permit (INAD #2573) for treating Atlantic
and Pacific salmon and some species of bass and endangered sturgeon (R.A.
Schnick, personal communication). Special precautions must be enforced in these
cases. For example, in at least one instance, salmon culturists have one person
known as a "designated malachite green mixer." This worker is required to use a
rubber suit and gloves, face mask and respirator (D.E. Anderson, personal
communication). In emergency situations, other fish culturists may also obtain
legal authorization to use the fungicide on a case-by-case basis. In this
protocol, the agency's fisheries chief contacts Dr. Donald Gable, Chief, Division
of Drugs for Food Producing Animals, FDA (telephone number [phone]), and
describes the problem. This officer then may decide on-the-spot to give FDA
authorization to use malachite green for that situation (R.A. Schnick, personal
communication).

Also, the states of Idaho, Oregon and Washington are attempting to obtain an
extension of the USFWS INAD permit for their most critical situations. In
response to these state requests, the FDA has required action to assure a zero
level of malachite green in hatchery effluents within two years (via charcoal
filtration), strict accountability for the chemical, employee safety training and
equipment, and USFWS monitoring of state usage and records (Anonymous 1987).

Much research has been done in attempt to find a suitable replacement for
malachite green. To date, no new chemical has proven very effective. If workers
do use malachite green, it is highly recommended that protective clothing and
respirators be used to prevent contamination and inhalation of the chemical.

21