vvEPA
United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S1-81-007 Feb. 1981.
Project Summary
Chromosome Aberrations in
Peripheral Lymphocytes of
College Students as a
Response to Photochemical
Air Pollution
Allan R. Magie, David E. Abbey, and Willard R. Centerwall
This research project confirms and
extends to a more homogeneous
group the observations of Scott and
Burkard in their study of chromosome
aberrations in the peripheral lympho-
cytes of students attending the
University of Southern California. This
study compares whether the inci-
dence of chromosome aberrations in
students emigrating from and to an
area with high levels of photochemical
air pollutants versus an area of low
levels differed significantly from
students indigenous to the respective
areas.
The data does not support the hypo-
thesis that living (or attending school)
in the South Coast Air Basin of
Southern California significantly af-
fects the integrity of peripheral blood
lymphocyte chromosomes. Nor is
there evidence that those living in
areas of little or no photochemical air
pollution have statistically signifi-
cant fewer chromosome abnormalities.
This Project Summary was devel-
oped by EPA's Health Effects Research
Laboratory, Research Triangle Park,
NC, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title /see Project Report order-
ing information at back).
Introduction
Conflicting evidence continues to
accumulate that exposure of human,
animal, and plant tissues to the
constituents of photochemical air
pollution may result in increased
chromosome aberrations. Of particular
concern is the potential danger that
exposure of humans to existing ambient
levels of photochemical smog may
result in mutagenic changes leading to
congenital anomalies. Although studies
on ozone effects on human cells have
been limited, considerable evidence
does exist for the induction of both point
and chromosome aberrations in several
animal species.
Methods
Two-hundred and nine (209) male
and female first-year students at the La
Sierra campus of Loma Linda University
(high smog) and two-hundred and six
(206) male and female first-year
students at Pacific Union College (low
smog) were pre-enrolled after
completing a lifestyle questionnaire or
responding to a similar telephone-
administered questionnaire. They were
assigned to groups according to their
previous life-time exposure to air
-------
pollution and the college in which they
were matriculating. This resulted in four
groups: low smog to low smog, low
smog to high smog, high smog to low
smog, and high smog to high smog.
Blood samples and updated health
histories were obtained from the
students at the following times:
September-October 1976 (410
students): November 1976 (407
students); April 1977 (369 students);
and September-October 1977 (317
students). All blood samples were
cultured and slides prepared by the
Genetics Research and Chromosome
Services, Loma Linda University
Medical Center. One hundred cellsfrom
each student were analyzed for
chromosome and chromatid aberra-
tions at Utah Biomedical Test
Laboratory.
Conclusions
Due to technical difficulties in blood
drawings three and four, statistical
analyses of all groups for all four blood
sampling periods was not completed. It
is felt that this study is significant,
however, in that four contrasting
groups, with respect to exposure to
photochemical air pollution in the South
Coast Air Basin of Southern California,
were cytogenetically examined at the
conclusion of the high pollution season
and again two and six months later.
No statistically significant differences
in the aberration rates for the types of
chromosome abnormalities studied
were observed between the four
exposure groups of students at each of
the sampling periods or among the
same students over the duration of the
study. The elevated rate of stable
changes at the initial blood sampling
period for males in the low-to-high
group was, however, an exception of
statistical importance. This group did
not show a statistically significant
elevation in rate when the initial
criterion of allowing students to arrive
on campus 15 days prior to blood
drawing was applied, but the rate
became increasingly elevated over the
other groups and became statistically
significant when two increasingly
stringent criteria for arrival time were
applied, namely within 3 days of blood
drawing and then within 1 day.
Increased differences were also noted
for females in the same group, but these
were not as significant as they were for
the males. Moreover, these elevated
rates dropped off by the second blood
sampling 2 months later.
Recommendations
Future studies can reduce the intra-
student variability by scoring a
minimum of 200 metaphases.
Study group size could be reduced by
using more stringent exclusion criteria
such as those used for statistical
analyses in this study.
An on-going validity study to check
accuracy in chromosome scoring
should be carried out at an independent
laboratory paralleling any cytogenetic
study.
A carefully controlled laboratory
study exposing students having no
previous exposure to significant levels
of ozone could be carried out to test the
"shock effect" hypothesis.
Allan R. Magie, David E. Abbey, and Willard R. Centerwall are with Loma Linda
University, Loma Linda, CA 9235O.
Dorothy C. Calafiore is the EPA Project Officer (see below).
The complete report, entitled "Chromosome Aberrations in Peripheral Lympho-
cytes of College Students as a Response to Photochemical Air Pollution,"
/Order No. PB 81-152 506; Cost: $14.00, 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
Research Triangle Park, NC 27711
: U.S. GOVERNMENT PRINTING OFFICE: 1981 -757-012/7173
------- |