SEPA
United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S1 -81 -040 July 1981
Project Summary
Temporal Variability of
Toxic Contaminants in
Animal Diets
J. P. Bercz
Uncertified commercial research
animal feed (Purina Chow™) was
analyzed over forty-one months to
determine essential and trace elements
and toxic contaminants. Parametric
statistics and graphic chronologic
progressions of the results are pre-
sented for cat, monkey, rodent (rat/
mouse), guinea pig and dog diets.
Concentrations of toxic contaminants
are discussed in terms of Maximum
Allowable Concentrations (MAC)
proposed by EPA. The impact of un-
desirable contaminants on in vivo
animal studies is analyzed. Practical
aspects of cost-effectiveness of feed
analysis in a major research setting is
discussed.
This Project Summary was develop-
ed by EPA's Health Effects Research
Laboratory, Cincinnati, OH, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
In recent years increasing attention
has focused on nutritional and toxico-
logical qualities of feed and water
administered to experimental animals.
Governmental regulations were pro-
posed by the Food and Drug Administra-
tion and by EPA tocontrol quality of non-
clinical animal testing. Within the broad
range of requirements for quality assur-
ance, the Good Laboratory Practices
(GLP) regulation mandates description
and periodic analysis of animal feed.
Maximum Allowable Concentrations
(MAC) for critical toxic substances in
feed have been proposed by EPA based
on the recommendation of the National
Research Council's Committee for Long
Term Holding of Laboratory Rodents.
In spite of the growing concern about
feed contamination, only limited infor-
mation is available in the literature
about types, sources and timing of
contamination.
In the past literature several authors
dealt extensively with rodent feed con-
tamination and its potential impact on
toxicological procedures. Literature
listings of multiple assays on rodent
chow provide neither source nor
chronology of sampling.
Objectives
This report summarizes our labora-
tory's experiences since mid-1976 in
testing uncertified animal diets. In
compliance with Agency-wide policy for
quality assurance and in anticipation of
the imminent GLP regulations, we
initiated analyzing all batches of feed
purchased from Purina. The mode of
analysis was retrospective, e.g. sampling
and analysis was done immediately
upon receipt of the feed lot. Assay data
was available a- month later, by which
time the feed was dispensed for con-
sumption.
-------
The project included six diet types,
and thirty components were assayed in
each of these formulae during varying
segments of 41 contiguous months,
from June 1976 to December 1979
inclusive. Classification of these was as
follows:
• Essential elements, for which the
manufacturer specifies values in
composition charts.
• Toxic elemental and'molecular
contaminants for which MACs
have been proposed by EPA.
• Elements of undefined significance.
The manufacturer neither attempts
to control these, nor provides state-
ments regarding levels in feed.
The intent of this report is to: provide a
chronological "snapshot" of a popular
commercial feed; discuss the appro-
priateness of MACs; and evaluate meth-
ods of feed analysis.
Conclusions
Essential Elements - The range of
variations indicated reasonably rigid
control in the manufacturing process.
Mean concentrations of each elemental
component were comparable across
feed types, and corresponded to those
listed by the manufacturer in composi-
tion charts.
Toxic Contaminants
Cadmium - More than one third of all
observations on all feed types exceeded
the EPA limit. Had we obtained the
monthly analytical data before we
administered the feed to our rodents,
based on the EPA MAC, we would have
had to reject 34% of the lots. In practice,
the exclusion of the diets exceeding the
arbitrary MACs was not necessary due
to the nature of the studies being
undertaken in our laboratory.
Lead - The variability of this element
was particularly high in cat, monkey and
rodent chows. The ambient range in
rodent feed presented a practical con-
cern to our investigators because of a
previous experience. During 1978, a
large rat cross-fostering study involving
low lead levels in drinking water had to
be invalidated because of an outlier
{2.59 mcg/g) lead level occurring in
rodent chow.
Mercury - This contaminant was
detected only in June 1979 in cat and
rodent feeds, both being lower than the
MAC recommended by EPA.
Arsenic - Arsenic appeared to be the
most variable of all contaminants across
feed types but none of the observations
exceeded the EPA MAC.
Selenium - The chronological pro-
gression of this element showed sudden
and simultaneous elevation in all feeds,
followed by persistence and slow decay
during the period studied. The biological
significance of this incidence could not
be assessed.
Malathion - Ma lath ion was the most
stable and best controlled pesticide
residue in all diets tested.
DDTs - DDTs were ubiquitous con-
taminants appearing in spikes at regular
frequency throughout the study, sug-
gesting seasonality.
PCBs - Rodent diet, the most frequently
encountered intoxicological laboratories,
showed two instances of contamination.
Based on levels obtained, it is our
conclusion that the contamfnation peaks
were not sufficient to alter liver function
in our animals. However, PBCs are
known carcinogens and based on this
fact, we would have probably discarded
the contaminated lots had we known
beforehand.
Since electrical equipment containing
PCBs is still in use in feed processing
plants, accidental spills are possible to
occur. Therefore, the need for pre-ad-
ministration surveillance of PCB is
warranted.
Aluminum - In view of our experiences
one cannot speculate as to the signifi-
cance of aluminum in animal feeds. The
highest observed level in rodent feed
was about 10-fold over the level one
might find in human food (oatmeal)
cooked in aluminum pots. From the
analytical data, it is not possible to
discern in what chemical form aluminum
was present in animal feed.
Barium - The cardiovascular toxicity
of this element received considerable
attention, especially in view of its
abundance in drinking water. Therefore,
feed barium levels are of significant
interest to many researchers.
An example of this concern emerged
in our laboratory when the rate of
gastrointestinal absorption of naturally
occurring barium in drinking water was
studied in rats. The study had to be
repeated after the investigators realized
that the ambient feed levels interfered
with the interpretation, since the rat
chow contained 2-5 times the amount
of barium that was present in the water
sample studied.
Strontium and Boron - Very little is
known about the potential impact of
these contaminants in the ppm range in
animal studies. The levels detected are
documented.
-------
The EPA author J. P. Bercz is with the Health Effects Research Laboratory,
Cincinnati, OH 45268.
W. Emile Coleman is the EPA Project Officer (see below).
The complete report, entitled "Temporal Variability of Toxic Contaminants in
A nimal Diets," (Order No. PB 81 -205 9 73; Cost: $8.00, subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Health Effects Research Laboratory
U. S. Environmental Protection Agency
Cincinnati. OH 45268
> U.S. GOVERNMENT HUNTING OFFICE: 1W1 -757-012/7225
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
RETURN POSTAGE GUARANTEED
PS OOOOiM
------- |