Comments Regarding
Chapter 8. "Toxicology of Particulate Matter"
Of the External Review Draft of the Air Quality Criteria
Document for
Particulate Matter (PM)
By Joel N. Kline, M.D.
Associate Professor
Division of Pulmonary Medicine
University of Iowa
Overall, this document demonstrates that there exists
a serious lack in the research area involving children
and inhalation of particulates.
1. Section 8.2, page 8-2, Lines 26-27 notes:
“there are substantial differences in the
inhalability and deposition profiles of PM in humans
and rodents,” but does not note that age of
subjects also affects these profiles.
2. Similarly, Section 8.2, page 8-3, Lines 17-19
notes: “More research on particle dose
extrapolation is needed, therefore, to determine
species differences and the importance of exercise
and other factors influencing particle deposition in
humans that together can account for a 50-fold or
more difference in dose.” This should mention
the need to study children.
3. Section 8.2.2 [Metal Particles, Fumes, and
Smoke], pages 8-4 to 8-9 does not cover the
inhalation of lead, which is a significant pediatric
health hazard.
The chapter includes affirmative discussions of risks
to pediatric populations:
4. Section 8.2.1, page 8-4, Lines 12-14, discusses
the effects of inhalation of acid aerosols by
adolescent more sensitive than adults. asthmatics,
who appear to be
5. Table 8-10, page 8-79, Section 8.6, page 8-82,
lines 3-15, and Section 8.7, page 8-84, lines 11-15
review the studies by Linn et al in which healthy and
asthmatic children were exposed to H2SO4 alone or
H2SO4, ozone, and SO2 by inhalation; inhalation led
to symptoms but not bronchospasm in asthmatic
children; no symptoms in healthy children. Combined
exposures to PM and gaseous co-pollutants were found
by Thurston et al to have greater effects in a field
study then were found in laboratory conditions.
Animal studies addressing age of subjects were cited:
6. Section 8.4.1, page 8-36, describes the study
by Clarke et al in which young and old rats were
exposed to concentrated ambient PM. Young rats
developed mild inflammation which was significantly
worse than that seen in older rats.
7. Table 8-5, page 8-18 and Section 8.4.1, page
8-38 review a study by Johnston et al in which
exposure to PTFE fumes led to enhanced inflammation
in old mice relative to young mice
8. In Section 8.5.4, pages 8-70 and 8-71, lines
30-31 and 1-4 describe a study by Oberdorster et al
in which the investigators found that old rats
sensitized with endotoxin and then exposed to ozone
and ultrafine particles developed significantly
greater release of reactive oxygen species than young
rats.
9. Table 8-6, page 8-24 and Section 8.6, page 8-81
and 8-82, lines 24-31 and 1-2 describe a study by
Elder et al comparing the response to ultrafine
particles, ozone, and previous endotoxin inhalation
between young and old rats. In this setting, the
young rats had less cellular and mediator-defined
inflammation induced by the combined exposure than
the older rats.
Studies/manuscripts not reviewed in this document,
(identified by a Medline search using terms
“Particulate,” “Inhalation,” and
Children”) which are relevant to pediatric
inhalation exposures:
10. Mauderly JL. Animal models for the effect of
age on susceptibility to inhaled particulate matter.
Inhal Toxicol 2000;12(9):863-900.
11. Calderon-Garciduenas L, Mora-Tiscareno A,
Chung CJ, et al. Exposure to air pollution is
associated with lung hyperinflation in healthy
children and adolescents in Southwest Mexico City: a
pilot study. Inhal Toxicol 2000;12(6):537-611.
12. Schlipkoter HW, Dolgner R. [Air pollution and
biological defence (author's transl)]. Zentralbl
Bakteriol [B] 1981;172(4-5):299-311.
13. Horak F, Jr., Studnicka M, Gartner C, et al.
[The effect of inhalable dust particles (PN10) on
lung function and respiratory symptoms of school
children in Lower Austria]. Wien Klin Wochenschr
2000;112(3):126-32.
14. Cox FA, Stiller-Winkler R, Hadnagy W, Ranft U,
Idel H. Soluble tumor necrosis factor receptor (sTNF
RII) in sera of children and traffic-derived
particulate air pollution. Zentralbl Hyg Umweltmed
1999;202(6):489-500.
15. Raghunath R, Tripathi RM, Kumar AV, Sathe AP,
Khandekar RN, Nambi KS. Assessment of Pb, Cd, Cu, and
Zn exposures of 6- to 10-year-old children in Mumbai.
Environ Res 1999;80(3):215-21.
16. von Mutius E, Fritzsch C, Weiland SK, Roll G,
Magnussen H. Prevalence of asthma and allergic
disorders among children in united Germany: a
descriptive comparison. Bmj 1992;305(6866):1395-9.
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