United States
Environmental Protection
1=1 m m Agency
EPA/690/R-09/071F
Final
9-29-2009
Provisional Peer-Reviewed Toxicity Values for
White Mineral Oil
(CASRN 8012-95-1 and 8020-83-5)
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

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Commonly Used Abbreviations
BMD
Benchmark Dose
IRIS
Integrated Risk Information System
IUR
inhalation unit risk
LOAEL
lowest-observed-adverse-effect level
LOAELadj
LOAEL adjusted to continuous exposure duration
LOAELhec
LOAEL adjusted for dosimetric differences across species to a human
NOAEL
no-ob served-adverse-effect level
NOAELadj
NOAEL adjusted to continuous exposure duration
NOAELhec
NOAEL adjusted for dosimetric differences across species to a human
NOEL
no-ob served-effect level
OSF
oral slope factor
p-IUR
provisional inhalation unit risk
p-OSF
provisional oral slope factor
p-RfC
provisional inhalation reference concentration
p-RfD
provisional oral reference dose
RfC
inhalation reference concentration
RfD
oral reference dose
UF
uncertainty factor
UFa
animal to human uncertainty factor
UFC
composite uncertainty factor
UFd
incomplete to complete database uncertainty factor
UFh
interhuman uncertainty factor
UFl
LOAEL to NOAEL uncertainty factor
UFS
subchronic to chronic uncertainty factor
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PROVISIONAL PEER-REVIEWED TOXICITY VALUES FOR
WHITE MINERAL OIL (CASRN 8012-95-1 AND 8020-83-5)
Background
On December 5, 2003, the U.S. Environmental Protection Agency's (U.S. EPA) Office of
Superfund Remediation and Technology Innovation (OSRTI) revised its hierarchy of human
health toxicity values for Superfund risk assessments, establishing the following three tiers as the
new hierarchy:
1.	U.S. EPA's Integrated Risk Information System (IRIS).
2.	Provisional Peer-Reviewed Toxicity Values (PPRTVs) used in U.S. EPA's Superfund
Program.
3.	Other (peer-reviewed) toxicity values, including:
~	Minimal Risk Levels produced by the Agency for Toxic Substances and Disease
Registry (ATSDR),
~	California Environmental Protection Agency (CalEPA) values, and
~	EPA Health Effects Assessment Summary Table (HEAST) values.
A PPRTV is defined as a toxicity value derived for use in the Superfund Program when
such a value is not available in U.S. EPA's IRIS. PPRTVs are developed according to a Standard
Operating Procedure (SOP) and are derived after a review of the relevant scientific literature
using the same methods, sources of data, and Agency guidance for value derivation generally
used by the U.S. EPA IRIS Program. All provisional toxicity values receive internal review by
two U.S. EPA scientists and external peer review by three independently selected scientific
experts. PPRTVs differ from IRIS values in that PPRTVs do not receive the multiprogram
consensus review provided for IRIS values. This is because IRIS values are generally intended
to be used in all U.S. EPA programs, while PPRTVs are developed specifically for the Superfund
Program.
Because new information becomes available and scientific methods improve over time,
PPRTVs are reviewed on a 5-year basis and updated into the active database. Once an IRIS
value for a specific chemical becomes available for Agency review, the analogous PPRTV for
that same chemical is retired. It should also be noted that some PPRTV documents conclude that
a PPRTV cannot be derived based on inadequate data.
Disclaimers
Users of this document should first check to see if any IRIS values exist for the chemical
of concern before proceeding to use a PPRTV. If no IRIS value is available, staff in the regional
Superfund and Resource Conservation and Recovery Act (RCRA) program offices are advised to
carefully review the information provided in this document to ensure that the PPRTVs used are
appropriate for the types of exposures and circumstances at the Superfund site or RCRA facility
in question. PPRTVs are periodically updated; therefore, users should ensure that the values
contained in the PPRTV are current at the time of use.
It is important to remember that a provisional value alone tells very little about the
adverse effects of a chemical or the quality of evidence on which the value is based. Therefore,
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users are strongly encouraged to read the entire PPRTV document and understand the strengths
and limitations of the derived provisional values. PPRTVs are developed by the U.S. EPA
Office of Research and Development's National Center for Environmental Assessment,
Superfund Health Risk Technical Support Center for OSRTI. Other U.S. EPA programs or
external parties who may choose of their own initiative to use these PPRTVs are advised that
Superfund resources will not generally be used to respond to challenges of PPRTVs used in a
context outside of the Superfund Program.
Questions Regarding PPRTVs
Questions regarding the contents of the PPRTVs and their appropriate use (e.g., on
chemicals not covered, or whether chemicals have pending IRIS toxicity values) may be directed
to the U.S. EPA Office of Research and Development's National Center for Environmental
Assessment, Superfund Health Risk Technical Support Center (513-569-7300), or OSRTI.
INTRODUCTION
Food-grade and medicinal-grade mineral oils are pure (aromatic-free) mixtures of highly
refined paraffinic and naphthenic petroleum hydrocarbons. Mineral oil formulations are often
designated by their content (P for paraffinic, N for naphthenic), viscosity (reported in mm2/sec at
40°C), and whether the mixture was hydrotreated (H indicating catalytic hydrogenation). Thus, a
mixture designated as P15H is a hydrotreated paraffinic mineral oil with a viscosity of
15 mm2/sec (WHO, 2003). Mineral oils of lower molecular weight (<480) and carbon range are
most pertinent to the C9-C32 petroleum fraction. Among the mineral oils that have been studied
for toxicity in laboratory animals, the most relevant mixtures are: N10A, N15H, P15H, N70A,
N70H, P15H, Marcol 72, Marcol 82, and EZL 600. Paraffinic waxes, which are related
mixtures, include many compounds outside the carbon range of interest (e.g., C>32) for this
petroleum fraction and, thus, were not considered in this review.
No chronic or subchronic RfDs or RfCs or cancer assessment for mineral oil are available
on IRIS (U.S. EPA, 2009), the Drinking Water Standards and Health Advisory list
(U.S. EPA, 2006) or in the HEAST (U.S. EPA, 1997). No documents for mineral oil are listed in
the Chemical Assessments and Related Activities (CARA) list (U.S. EPA 1991, 1994). The
American Conference of Governmental Industrial Hygienists (ACGIH) recommends a threshold
limit value-time-weighted average (TLV-TWA) of 0.2 mg/m3 for mineral oil used in metal
working and a TLV-TWA of 5 mg/m3 for pure, highly and severely refined mineral oil; the
critical effects are given as lower respiratory tract irritation and pulmonary function
(ACGIH, 2007). The National Institute of Occupational Safety and Health (NIOSH)
recommended exposure limit (REL) for mineral oil mists is 5 mg/m3 to protect against
respiratory effects (NIOSH, 2008). The Occupational Safety and Health Administration (OSHA)
permissible exposure limit (PEL) is also 5 mg/m3 (OSHA, 2008). Neither ATSDR nor the
International Agency for Research on Cancer (IARC) has published documents on mineral oil
toxicity or carcinogenicity (ATSDR, 2007; IARC, 2008). The National Toxicology Program
(NTP, 2008) has not performed toxicity or carcinogenicity assessments for mineral oil, and this
compound is not on the 11th Report on Carcinogens (NTP, 2005). The World Health
Organization (WHO, 2003) has published a review of food-grade mineral oils and paraffin
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waxes, which was reviewed for pertinent information. In addition, reviews of mineral oil
toxicity published by the Massachusetts Department of Environmental Protection
(MADEP, 2003) and the Total Petroleum Hydrocarbon Criteria Working Group
(TPHCWG, 1997) were consulted.
To identify toxicological information pertinent to the derivation of provisional toxicity
values for mineral oil, update literature searches (January 2002-August 2009) of the following
databases: MEDLINE, TOXLINE, BIOSIS, TSCATS, CCRIS, GENETOX, DART/ETIC,
HSDB, and Current Contents were conducted to August, 2009, to identify studies published
since the MADEP (2003) review.
REVIEW OF PERTINENT DATA
Human Studies
Oral Exposure
Oral mineral oil has long been used therapeutically in humans to treat constipation. The
North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHN)
suggests a maintenance dose of 1-3 mL/kg-day for oral use of mineral oil to treat constipation in
children older than 1 year of age (NASPGHN, 2006); this is roughly equivalent to a dose of
870-2600 mg/kg-day1. In their guidelines for treatment of constipation, NASPGHN (2006)
reported that long-term studies support the safety and efficacy of mineral oil use; the only study
cited, however, was Clark et al. (1987) (reviewed below). The NASPGHN (2006) also noted
that, while mineral oil could theoretically interfere with absorption of fat-soluble vitamins, there
was no evidence in the literature to support this hypothesis.
Clark et al. (1987) evaluated serum levels of B-carotene, retinol and a-tocopherol before
and after 4 months of mineral oil treatment in 25 children (2-14 years of age, mean age
7.8 years) diagnosed with chronic constipation. Neither the composition nor the
physical/chemical parameters of the mineral oil were reported. Mean mineral oil doses
administered to the children were 4.0, 2.9, 2.1, and 1.4 mL/kg-day (approximately 3500, 2500,
1800, and 1200 mg/kg-day; with an average dose of 2250 mg/kg-day) for Months 1, 2, 3, and 4,
respectively. Treatment was administered between meals to reduce the possibility of
interference with vitamin absorption. Serum vitamin levels were measured monthly during
treatment. Serum levels of a-tocopherol were not affected by treatment. A significant increase
in serum retinol levels (50%, higher than basal levels,/* < 0.01) was observed at Month 3 only; at
other time points, retinol levels were higher with treatment, but not significantly different from
basal levels. Serum levels of B-carotene fell 30% after 1 month of treatment and remained lower
(36-54%)) throughout the treatment period, although the difference was statistically
distinguishable from controls (p < 0.05) only during Months 1-3 and not during Month 4. In
1 Dose conversions have been undertaken and presented throughout this section of the document to characterize the
equivalency between mg/kg-day and mL/kg-day for the reader using the following calculations. The specific
gravity of white mineral oil is 0.83-0.905; HSDB (2007). Using the midpoint of the range (0.87) and the density of
water (1000 mg/mL), a dose of 1 mL/kg-day is calculated to deliver 870 mg/kg-day (1 mL/kg-day x 0.87 x
1000 mg/mL), and a dose of 3 mL/kg-day is calculated to deliver 2600 mg/kg-day (3 mL/kg-day x 0.87 x
1000 mg/mL).
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their discussion, the authors cited an earlier study of 19 children treated with mineral oil for up to
6 years with no effect on prothrombin time or serum retinol or a-tocopherol levels
(Ballantine et al., 1986, as cited in Clark et al., 1987), although true baseline (pretreatment)
measurements were not included in the study. In other studies cited by the authors, fecal
carotene excretion was markedly increased in five adults treated with mineral oil for 5 months
(Mahle and Patton, 1947, as cited in Clark et al., 1987), and visual dark adaptation (a measure of
retinol deficiency) was not affected in 28 patients (age not specified) treated with 5 mL/kg-day
(about 4350 mg/kg-day) mineral oil for 131 days (Isaacs et al., 1940, as cited in Clark et al.,
1987).
Speridiao et al. (2003) evaluated anthropometric parameters in 25 children (ages
2-12 years) treated with mineral oil and increased dietary fiber (for chronic constipation) for up
to 90 days. Chronic constipation is associated with anorexia, so anthropometric parameters,
together with food intake diaries, were used to assess improvement in nutritional status
associated with treatment. The composition and physical/chemical parameters of the mineral oil
were not reported. The median mineral oil dose was 1.0 mL/kg-day (about 870 mg/kg-day). In
16 patients who completed the treatment, height, weight, and midarm muscle area were
unchanged, while triceps skinfold thickness and midarm circumference were significantly
increased. No other effects of mineral oil treatment were discussed.
In a prospective study comparing mineral oil with lactulose (a synthetic disaccharide
compound used in the treatment of constipation) in the treatment of chronic constipation,
Urganci et al. (2005) treated 20 children (2-12 years old, average age, 3.8 years) with mineral oil
for 8 weeks in conjunction with instructions for behavioral modification and increased fiber
intake. No information was provided on the composition or physical/chemical parameters of the
mineral oil. The mineral oil dose was initiated at 1 mL/kg-day and modified by the patients'
parents to achieve improvement in the symptoms; the mean effective dose was 1.88 mL/kg-day
(about 1600 mg/kg-day). Mineral oil treatment was judged to be superior to lactulose based on
compliance and symptom control. Compliance with mineral oil treatment was very high
(95% during Weeks 1-4 and 90% during the final 4 weeks), affected only by taste aversion in
1/20 and watery stools in 2/20 patients. The authors reported that families considered any side
effects minor and acceptable.
Gal-Ezer and Shaoul (2006) presented a case report of a 17-year old girl whose doctor
had prescribed treatment with 25 mL mineral oil twice daily for chronic constipation. The
mineral oil composition and physical/chemical parameters were not given. Without her doctor's
input, the patient had increased the dose to 400 mL daily (348,000 mg/kg-day) and continued
this treatment for at least 5 months before her follow-up visit. A physical examination at the
time of follow-up revealed no abnormalities. Serum levels of fat-soluble vitamins (A and E), as
well as calcium, phosphorus, alkaline phosphatase (ALP) (as measures of vitamin D status) and
prothrombin time (as a measure of vitamin K status) were measured as a precaution. All levels
were within normal limits.
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Inhalation Exposure
Studies of inhalation exposure to mineral oil are limited to analyses of the effects of
mineral oil mists. These studies are typically of workers exposed to mineral oil aerosols
generated from metalworking operations. It is unlikely that environmental releases of petroleum
hydrocarbons will result in the formation of aerosols of hydrocarbons in the C9-C32 range.
Thus, studies of mineral oil mists were not included in this review.
Lipoid pneumonia can occur when mineral oil is aspirated into the lungs during oral
therapeutic use (NASPGHN, 2006); however, this route of exposure is not likely to occur under
environmental exposure conditions.
Animal Studies
Oral Exposure
Subchronic Studies—In a subchronic feeding study, Baldwin et al. (1992) administered
two food grade white oils to F344 rats for 90 days at dietary concentrations of 0, 10, 100, 500,
5000, 10,000, or 20,000 ppm. The test materials were oleum-treated white oil (OTWO) and
hydro-treated white oil (HTWO); both of which were derived from naphthenic crudes. OTWO
had a specific gravity of 0.874 at 15°C and a viscosity of 26 mm2/sec at 40°C; HTWO had a
specific gravity of 0.878 at 15°C and a viscosity of 69 mm2/sec at 40°C. Neither the average
molecular weight nor the carbon range of the materials was reported. The oils were dissolved in
"DISTOL"-grade hexane for diet preparation; this solvent was also incorporated into the control
diet (fed to groups of 20 rats/sex). Only two experiments were conducted; the first used only the
three highest concentrations and groups of 10 male and 10 female rats per concentration, while
the second used the entire range reported above and 10 female rats per concentration. The rats
were given the diet ad libitum for 13 weeks; ranges of intakes were estimated by the authors and
are reported below in Table 1.
Table 1. Estimated Dose Ranges for White Oil Intakea
Test Material
Dietary
concentration
(ppm)
Experiment 1
Experiment 2
Male Dose
Range
(mg/kg-day)
Female Dose
Range
(mg/kg-day)
Female Dose
Range
(mg/kg-day)
OTWO
10
-
-
0.65-1.2
100
-
-
6.5-12.2
500
-
-
33.5-58.2
5000
245-455
298-482
337-594
10,000
490-852
595-979
661-1163
20,000
1039-1812
1214-1920
1336-2321
HTWO
10
-
-
0.66-1.2
100
-
-
6.4-11.5
500
-
-
32.5-57.6
5000
244-441
294-481
320-576
10,000
506-894
592-975
664-1213
20,000
1009-1744
1216-1927
1327-2225
aBaldwin et al., 1992
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Clinical observations were made daily, while body weight and food intake were recorded
weekly (Baldwin et al., 1992). Experiment 1 included hematology (packed cell volume,
erythrocyte count [RBC], total leukocyte count [WBC], platelet count, hemoglobin concentration
[Hb], mean corpuscular volume [MCV], mean corpuscular hemoglobin [MCH], mean
corpuscular hemoglobin concentration [MCHC], and erythrocyte and platelet volume distribution
width) and clinical chemistry analyses (glucose, total protein, blood urea nitrogen [BUN],
calcium, phosphate, electrolytes, total cholesterol, triglycerides, total bilirubin, creatinine,
alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [ALP],
gamma glutamyl transferase [GGT], and lactate dehydrogenase [LDH]) on blood samples
collected at sacrifice.
Necropsy procedures differed between the two experiments (Baldwin et al., 1992). In the
first experiment, all animals were examined grossly, and brain, heart, liver, kidneys, spleen, and
testes were weighed. Histopathology examinations were made on a comprehensive list of tissues
(not specified) from control and 20,000-ppm animals, as well as on the lung, liver, kidneys,
spleen, and mesenteric lymph nodes of 5000- and 10,000-ppm animals. Tissue analysis for
hydrocarbons was performed on 5 animals in the control and 20,000-ppm groups; it is not clear
whether these animals were from the initial group of 10 or were maintained as a satellite group.
In the second experiment, 5 rats from the 500- and 10,000-ppm groups were sacrificed after
25 days, and all other animals were sacrificed after 13 weeks. Liver and spleen were weighed,
and these organs, together with the mesenteric lymph nodes, were subjected to microscopic
examination.
All rats survived the treatment, and there were no clinical signs of toxicity
(Baldwin et al., 1992). A statistically significant increase (data and magnitude not reported;
p < 0.05 compared with controls) in food intake was noted during Weeks 3-6 in males exposed
to 20,000-ppm OTWO; there were no other effects on food intake. The authors did not discuss
results of body weight measurements nor were data on this endpoint provided. Increases in the
numbers of leukocytes and granulocytes (data not given) were noted in high-dose (20,000 ppm)
rats of both sexes and with both test materials; in addition, females given this concentration of
OTWO were reported to have hypochromic microcytic anemia (data not shown; characterized by
the study authors as "slight"). Statistically significant changes in several clinical chemistry
parameters were observed in female rats exposed to >5000 ppm of both oils, with more
pronounced effects occurring with exposure to OTWO than with HTWO. A few changes were
observed in males, but they were far more limited. The observed changes in females (increased
bilirubin, ALT, and AST, and >4-fold increased GGT) are suggestive of a potential cholestatic
effect in the liver, while the changes observed in males are of uncertain significance. Table 2
shows the statistically significant clinical chemistry changes in both sexes; these data were
collected during Experiment 1, as clinical chemistry was not evaluated during Experiment 2.
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Table 2. Selected Clinical Chemistry Changes in Rats Fed Mineral Oils in the
Diet for 90 Daysa
Parameter
Control
OTWO (ppm)
HTWO (ppm)
5000
10,000
20,000
5000
10,000
20,000
Males
ALP (IU/L)
386
353
350b
334°
373
375
366
Triglycerides
(mmol/L)
1.29
1.05
0.77°
0.84°
1.12
1.12
0.74°
B Globulin (g/L)
19
21
21
22b
21
20
21
Females
Bilirubin (|imol/L)
3.50
3.40
3.80
4.30b
3.40
3.70
3.70
ALT (IU/L)
59.00
82.60
99.30°
96.70°
91.30b
84.00
92.20b
AST (IU/L)
120.00
148.00
175.00
180.00b
164.00
152.00
160.00
GGT (IU/L
0.40
0.60
1.80b
2.10b
0.20
0.40
0.80
Cholesterol (mmol/L)
2.31
2.08b
2.15
2.11
2.24
2.32
2.04°
Triglycerides
(mmol/L)
0.74
0.57
0.35°
0.34°
0.57
0.56
0.44°
Albumin (g/L)
58.00
52.00°
51.00°
47.00°
54.00
53.003
53.00b
B Globulin (g/L)
18.00
24.00°
25.00°
28.00°
21.00b
21.00a
23.00°
A:G
1.37
1.08°
1.07°
0.94°
1.22
1.17a
1.15°
Glucose (mmol/L)
2.60
2.90b
2.80
3.00°
2.70
2.70
2.70
"Baldwin et al., 1992; data from Experiment 1
bSignificantly different from control, p < 0.05
><0.01
Significant (p < 0.05) increases in absolute liver and spleen weight were observed in male
rats treated with >10,000-ppm OTWO and in female rats treated with >5000 ppm of either oil
(although liver weights were not increased at these concentrations in Experiment 2)
(Baldwin et al., 1992). Liver-weight increases ranged up to 34% higher than controls in female
rats, while spleen weights were increased by up to 80% or more. In addition, absolute kidney
weights were significantly increased (8%) in female rats exposed to >10,000-ppm OTWO but
not in those exposed to HTWO. Neither body weight data nor organ weights adjusted for body
weight were reported, so it is difficult to interpret the importance of the reported changes in
absolute organ weights. The authors reported enlarged mesenteric lymph nodes in females at all
dose levels and in males fed >5000-ppm OTWO, but weights were not reported. Table 3 shows
the statistically significant organ weight changes. Analysis of tissues for hydrocarbon residues
indicated that tissue levels were ~4- to 5-fold higher in females than in males, regardless of the
test material. The concentrations of total hydrocarbon residues in the liver and mesenteric lymph
nodes of female rats averaged 11.5 and 6.55 mg/g (respectively) for OTWO and 9.2 and 4.22
(respectively) for HTWO. In contrast, the concentrations in the liver and mesenteric lymph
nodes of male rats averaged 2.36 and 1.76 mg/g (respectively) for OTWO and 1.76 and <1.0
(respectively) for HTWO. Hydrocarbon residues were not detected in control animal tissues.
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Table 3. Selected Changes in
Mean Absolute Organ Weight (g) in Rats Fed

Mineral Oils for 90 Daysa





OTWO (ppm)
HTWO (ppm)
Parameter
Control
5000
10,000
20,000
5000
10,000
20,000
Males
Liver, Experiment 1
11.36
11.60
12.42b
12.23b
12.04
11.86
11.29
Spleen, Experiment 1
0.68
0.74
0.80b
0.83b
0.77°
0.72
0.74
Females
Liver, Experiment 1
6.19
7.60b
8.21b
8.79b
6.70°
7.09b
7.10b
Liver, Experiment 2
6.11
7.42b
8.19b
7.84b
6.43
6.75
6.62
Spleen, Experiment 1
0.44
0.72b
0.81b
0.89b
0.52b
0.53b
0.63b
Spleen, Experiment 2
0.45
0.64b
0.77b
0.81b
0.48
0.52°
0.55b
Kidney, Experiment 1
1.26
1.31
1.36b
1.35b
1.25
1.28
1.26
aBaldwinetal., 1992
V<0.01
Significantly different from control, p < 0.05
The authors reported all of the histopathology findings qualitatively; no incidences were
reported (Baldwin et al., 1992). Histopathological findings included macrophage aggregates and
syncytia in the mesenteric lymph nodes of all groups, including controls, with greater numbers in
the treated rats. The lymph nodes of treated rats also contained granulomatous foci at dietary
concentrations of >5000 ppm in males and females exposed to HTWO and in males exposed to
OTWO; these findings were observed at concentrations as low as 100 ppm in females exposed to
OTWO. Microgranulomas and granulomas were observed in the livers of treated rats; the
lesions ranged from clusters of macrophages, lymphocytes, epithelioid cells, and fibroblasts to
granulomas with areas of necrosis and hepatocellular degeneration and inflammation in the
surrounding parenchyma. Accompanying changes included slight-to-moderate Kupffer cell
hypertrophy, vacuolation, and pigmentation. These hepatic lesions were observed at
concentrations of >10,000 ppm in males exposed to OTWO (no lesions were observed in males
exposed to HTWO) and in females at concentrations >100-ppm OTWO or >500-ppm HTWO.
In the spleen, chronic capsular splenitis was observed in males exposed to >5000 ppm of either
oil and in females exposed to 20,000-ppm OTWO; however, the authors expressed uncertainty as
to the relationship of this effect to treatment. Extramedullary hemopoiesis was observed in the
spleens of females exposed to >5000 ppm of either oil.
This study identifies a LOAEL of 100 ppm (6.5-12.2 mg/kg-day) for OTWO based on
liver granulomas in female rats, with a NOAEL of 10 ppm (0.65-1.2 mg/kg-day) (Baldwin et al.,
1992). The LOAEL for HTWO is 500 ppm (32.5-57.6 mg/kg-day), also based on liver
granulomas in female rats; the NOAEL is 100 ppm (6.4-11.5 mg/kg-day). Although the authors
noted increased incidences of macrophage aggregates and syncytia in the lymph nodes of all
treated rats, these changes are not biologically significant. In an assessment of the lymph node
lesions reported in several studies of mineral oils and waxes, Carlton et al. (2001) concluded that
the lymph node changes (variously termed microgranulomas, histiocytosis, and
reticuloendothelial-cell hyperplasia) did not appear to have biological significance in the rat, as
these changes have been observed in control F344 populations and have not been linked to
adverse effects. Fleming et al. (1998) characterized these changes as focal accumulations of
vacuolated macrophages, with no evidence of inflammation or cell damage. Further,
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WHO (2003) noted that, in long-term studies of higher molecular weight mineral oils, these
lymph node changes did not progress to more severe effects; thus, WHO (2003) considered the
lesions to be markers of exposure rather than markers of effect.
Smith et al. (1995) published the results of a subchronic toxicity study of four white
mineral oils in beagle dogs and Long-Evans rats that was conducted in 1977 but had not
previously been published. The properties of the mineral oils (Marcol 72, Marcol 82, EZL 550,
and EZL 600) are shown in Table 4; average molecular weight was not reported. The oils were
all derived from paraffinic crude oil; no other information on their composition was reported.
Groups of 4 dogs/sex/dose were fed the test materials in the diet at concentrations of 0, 300, or
1500 ppm for 13 weeks. Daily observations for clinical toxicity were made, and food intake was
measured daily. Body weights were recorded weekly at the time of physical examination and
palpation for masses. Ophthalmoscopic examinations were administered before and at the
conclusion of exposure. Hematology (Hb, Hct, RBC, erythrocyte morphology, total and
differential WBC count, and clotting time), clinical chemistry (ALT, ALP, BUN, creatinine,
glucose, total protein, albumin, globulin, and albumin/globulin ratio) and urinalysis (gross
appearance, protein, glucose, pH, specific gravity, ketones, bilirubin, and occult blood) were
evaluated after 1 month and at the end of exposure; in addition, serum levels of vitamins A and
D3 were measured in control and high-dose dogs at study termination. Upon sacrifice, all
animals were necropsied and organ weights (adrenals, brain, kidneys, liver, ovaries/testes,
pituitary, and thyroid) determined. Major organs (not specified) of control and high-dose
animals were evaluated for histopathology, along with identified target organs in intermediate
dose groups.
Table 4. Properties of Test Materials21
Property
Marcol 72
Marcol 82
EZL 550
EZL 600
Purification process
Acid treatment
Hydrogenation
Hydrogenation
Hydrogenation
Viscosity @ 40°C
(centistokes)
12.3
13.8
65.9
31.6
Density at 15°C (g/m3)
0.838
0.842
0.864
0.854
Average carbon
distribution
C14-C38
C16-C34
C23-C44
C20-C36
"Smith etal., 1995
The authors indicated a mild laxative effect of all of the test materials, with occasional
diarrhea and mucoidal and mucohemorrhagic discharge (Smith et al., 1995). In addition, the
frequency of vomiting was reported to be increased relative to controls in the treated dogs. Data
on the frequencies of these observations were not reported, nor were the doses at which the
incidences of these effects were increased over controls. No treatment-related effects on body
weight or food consumption were reported. Based on dietary intake and body weight
measurements, the authors estimated doses of 10 and 50 mg/kg-day in male dogs and 10 and
52 mg/kg-day in female dogs. The authors reported that there were no treatment-related effects
on hematology, clinical chemistry, urine parameters, or serum levels of vitamins A or D3.
Among these evaluations, the only data reported were erythrocyte and leukocyte counts, which
confirmed the lack of a clear effect on these endpoints. Similarly, there were no effects of
treatment on gross necropsy findings, organ weights or histopathology findings in any organ
evaluated. Data shown in the report included only relative liver and gonad weight, which were
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not affected by treatment. Examination of the liver, mesenteric lymph nodes, gastrointestinal
tract, and kidneys for oil deposition did not reveal any significant deposition.
It is not possible to clearly assign effect levels from the data in beagles. While the
authors reported mild laxative effects and increased frequency of vomiting in the treated animals,
these effects were also reported in control animals and the change relative to controls is unclear,
given the lack of data on incidence or frequency. No other effects were observed in the treated
beagles.
In the rat study, groups of 20 rats/sex/dose were fed the test materials at the same dietary
concentrations (0, 300, or 1500 ppm) for 13 weeks (Smith et al., 1995). Toxicological
parameters evaluated were the same as for dogs with a few differences. Food intake was
measured weekly in rats. Hematology analysis included reticulocyte count and prothrombin time
and was performed on one-half of the rats at 1 month; hematology, clinical chemistry (including
AST) and urinalysis were also evaluated on all rats at study termination. Serum levels of
vitamins were not assessed. Finally, in rats, the liver, mesenteric lymph nodes and spleen of
control and high-dose animals exposed to Marcol 72, Marcol 82, and EZL 550 were re-examined
in 1990 in response to another study that identified effects in these organs in F344 rats
(Baldwin et al., 1992).
According to the authors, treatment did not affect survival, physical appearance,
behavior, clinical signs, ophthalmology, body weight or food consumption in rats; data on these
endpoints were not reported (Smith et al., 1995). Using food intake and body weight
measurements, the authors estimated average doses of 21 and 108 mg/kg-day in males and 25
and 125 mg/kg-day in females. There was a significant (p < 0.05) increase (48% over controls)
in total leukocyte count in female rats treated with the high dose of EZL 550 and decreases (7%)
in total erythrocyte counts in female rats treated with both doses of EZL 600. Review of the data
on clotting time indicated changes (both increases and decreases) that did not show an obvious
pattern; these changes were not considered biologically significant by the researchers. The
authors indicated that there were no treatment-related differences in any organ weights or
histopathological findings (data not shown). Special staining of the liver, mesenteric lymph
nodes, gastrointestinal tract, and kidney for oil deposition did not indicate significant deposition.
In addition, the histopathology re-evaluation of the liver, mesenteric lymph nodes and spleen
confirmed the lack of findings in these organs.
This study identified a freestanding NOAEL in Long-Evans rats of 108 or 125 mg/kg-day
(in males and females, respectively) for each of the test materials. The limited hematology
findings are not considered biologically significant in the absence of toxicological correlates.
In an effort to evaluate strain differences in responses to orally-administered mineral oils,
Firriolo et al. (1995) conducted subchronic studies of a low viscosity mineral oil (P15H; specific
gravity of 0.851 at 15°C and viscosity of 14.80 mm2/sec at 40°C) in female F344 and CRL:CD
rats. No other information on the composition of the mixtures was reported. Dietary
concentrations of 0, 0.2, and 2.0% by weight (w/w) were estimated by the authors to result in
mean doses of 0, 161, and 1582 mg/kg-day in F344 rats and 0, 158, and 1624 mg/kg-day in
CRL:CD rats. Groups of 10 female rats were fed the diets ad libitum for 92 days. Additional
groups of 10 female F344 rats were sacrificed after 30 and 61 days of treatment at 0 or
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2.0% P15H. Daily examination for clinical signs and mortality was performed, and body weight
and food consumption were recorded weekly. Upon sacrifice, blood was collected for
hematology (Hct, Hb, RBC, total and differential WBC count, platelet count, MCV, MCHC, and
reticulocyte count) and clinical chemistry (albumin, BUN, calcium, creatinine, electrolytes,
glucose, phosphorus, ALT, AST, ALP, GGT, total protein, total bilirubin, cholesterol, and
triglycerides) analyses. All animals were necropsied, and the heart, kidneys, liver, ovaries,
spleen, and mesenteric lymph nodes were weighed. Histopathology evaluation was restricted to
the liver, mesenteric lymph nodes and any gross lesions but included all treatment groups.
Hydrocarbon content of the liver, kidneys, spleen, and mesenteric lymph nodes was analyzed.
All rats survived to scheduled sacrifice, and there were no treatment-related effects on
clinical signs, body weight or food intake in either strain (Firriolo et al., 1995). Hematology and
clinical chemistry parameters were comparable to controls in CRL:CD rats. In contrast, F344
rats showed signs of leukocytosis (specifically, an increase in neutrophils as a percent of total
leukocyte count) beginning at Day 30, with a statistically significant elevation of leukocyte count
at Day 61 and evidence of a dose-response relationship after 92 days. After 92 days, neutrophils
as a percent of total WBC were increased 71% (p < 0.05) over controls in rats exposed to
2% P15H; the increase was not statistically significant in the low-dose group. A few clinical
chemistry parameters were also affected in F344 rats; GGT levels were increased over controls at
both concentrations (69 and 35% for the 0.2 and 2.0% groups, respectively, p < 0.05), and
triglycerides were significantly decreased in the 2.0% group (29%, p < 0.05). Other transient
changes in clinical chemistry parameters were observed at 30 days but not at 61 or 92 days. The
authors reported that the clinical chemistry changes were not toxicologically significant due to
the small magnitude of change, lack of dose-response relationship and consistency with
historical control ranges.
Absolute and relative liver weights were significantly increased at all sacrifice times in
F344 rats exposed to 2% P15H (20 and 30% above controls for absolute and relative weight,
respectively) and in the 0.2% group at study termination (10% increase in both parameters)
(Firriolo et al., 1995). In addition, absolute and relative weights of mesenteric lymph nodes were
significantly increased at all scheduled sacrifices in F344 rats in the 2% group (up to 3.7- to
3.8-fold higher than controls). Data were presented graphically. There were no
treatment-related changes in organ weights in CRL:CD rats. Analysis of mineral hydrocarbon
content in liver and mesenteric lymph nodes indicated greater deposition in F344 rats than in
CRL:CD rats at the same exposure concentration, especially in the liver (2- to 3-fold higher).
Levels of mineral hydrocarbons in the liver averaged 5586 and 8237 |ig/g in F-344 rats exposed
to 0.2 and 2% (respectively), compared with 1694 and 4069 |ig/g in CRL:CD rats exposed to the
same concentrations. In the mesenteric lymph nodes, levels of mineral hydrocarbons were
similar in the two strains of rat (1204 and 1543 |ig/g in F-344 rats exposed to 0.2 and 2%,
respectively, compared with 886 and 1408 |ig/g in CRL:CD rats).
Histologic changes in the liver, consisting of microgranulomas, were noted at study
termination in the F344 rats exposed to 0.2% P15H and at Days 61 and 93 in the F344 rats
exposed to 2% (Firriolo et al., 1995). The incidence of microgranulomas at study termination
was 45 and 95% in the 0.2 and 2% exposure groups, respectively; incidence in the controls was
not reported. In CRL:CD rats, an increase in minimal multifocal chronic inflammation
(incidence not reported) was observed at study termination in the 2% group; no microgranulomas
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were observed in any rats of this strain. Histiocytosis of the mesenteric lymph nodes was noted
at Day 30 in the 2% group of F344 rats. This effect progressed to discrete microgranuloma
formation over the course of the study. All F344 rats sacrificed on Day 61 had microgranulomas
in the mesenteric lymph nodes, and the incidence at study termination was 80 and 90% in the
0.2% and 2% exposure groups. This lesion was not observed in CRL:CD rats at either
concentration. This study identified a LOAEL of 161 mg/kg-day in F344 rats based on
microgranuloma formation in the liver (no NOAEL can be identified) and a LOAEL of
1624 mg/kg-day and NOAEL of 158 mg/kg-day in CRL:CD rats, based on an increase in
multifocal chronic inflammation of the liver. As noted above, histiocytosis of the lymph nodes is
not considered adverse (Fleming et al., 1998; Carlton et al., 2001; WHO, 2003).
Smith et al. (1996) administered seven highly refined white mineral oils in the diet to
F344 rats in two separate studies (six mineral oil samples [N10A, N15H, P15H, N70A, N70H,
P100H] in Study 1 and one [P70H] in Study 2). Purity of the test materials was not reported.
Table 5 shows the composition of the mineral oils and the study design. The basic study design
involved groups of 20/sex/dose given doses of 20-, 200-, 2000- or 20,000-ppm mineral oils for
90 days and then sacrificed, with a separate group of five/sex at the high dose evaluated for
accumulation of hydrocarbons in tissues. In the first study, an additional 10/sex/dose were
treated for 90 days and then followed for 28 untreated days. Daily observations were made for
clinical signs of toxicity, while body weights and food consumption were recorded twice weekly.
Ophthalmological examinations were conducted on control- and high-dose animals before study
commencement and at the end of the exposure period. At necropsy, hematology (MCV, RBC,
total and differential WBC count, platelet count, reticulocyte count, hematocrit [Hct], Hb, and
prothrombin time) and serum chemistry (albumin, albumin/globulin ratio, total bilirubin,
creatinine, electrolytes, ALT, AST, ALP, GGT, glucose, total protein, urea, and vitamin E
[Study 1 only]) were assessed. Selected organs (adrenals, brain, cecum, heart, kidneys, liver,
ovaries/testes, spleen, and thymus, as well as mesenteric lymph nodes in the tissue group of the
first study) were weighed. Comprehensive histopathology examinations were made on the
control- and high-dose groups, as well as microscopic examination of the lung, liver, kidneys,
mesenteric lymph nodes, spleen, and small intestine of all other groups.
Table 5. Test Material Descriptions and Study Numbera
Sample
Crude Type
Average MW
Carbon Range
Study
N10A
Naphthenic
320
15-30
1
N15H
Naphthenic
330
17-30
1
P15H
Paraffinic
350
18-30
1
N70A
Naphthenic
410
21-35
1
N70H
Naphthenic
420
22-37
1
P70H
Paraffinic
485
27—43
2
P100H
Paraffinic
510
28-45
1
aSmithetal., 1996
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There were no treatment-related effects on clinical signs, body weight, or ophthalmology
(Smith et al., 1996). The authors reported that occasional statistically significant differences in
body weight did not reach 10% change from control and were neither dose-related nor consistent
over time (data not shown). Food consumption was increased in the highest-dose group; this was
attributed to compensation for the caloric loss resulting from substitution of mineral oils for
food. Based on food consumption and body weights, the authors estimated daily intakes of test
material to be 1.7, 17, 173, and 1815 mg/kg-day in males and 2.0, 19, 190, and 1951 mg/kg-day
in females. Decreased erythrocyte counts (reduced by 2 to 4%,p< 0.05), Hb, and Hct (data not
shown) were noted in female rats given >2000-ppm N10A or P15H or 20,000-ppm N15H,
N70A, or N70H. Significant (p < 0.05) increases in total leukocyte counts (20-25%, usually
neutrophils and monocytes) were recorded in females treated with the 20,000-ppm N1 OA, N15H,
or P15H. Increases in leukocyte counts remained after the recovery period in females treated
with 20,000-ppm N15H or P15H and were increased (for the first time) in females treated with
P100H and allowed to recover. Increases in total leukocyte counts (+17 to 20%) were also
observed in males treated with 20,000-ppm N15H or P15H. No other hematological effects were
noted in the animals treated with mineral oils.
No treatment-related effects on clinical chemistry were reported in male rats
(Smith et al., 1996). In females treated with 20,000-ppm N10A, N15H, P15H, P70H, or P100H,
there were treatment-related increases in ALT, AST, and GGT. Increases in ALT and AST were
generally small (10—20%), while 1.75-3 fold increases (relative to control) in GGT were seen
with N1 OA, N15H, and P15H. The authors reported that other statistically significant clinical
chemistry changes (on ALP, serum glucose, albumin, and albumin/globulin ratio and total
protein) were smaller in magnitude and not dose-related (data not shown but discussed in text).
Measurement of vitamin E levels in the first study showed that treatment with N1 OA, N15H, or
P15H reduced vitamin E to 30% (in males) and 45% (in females) of control values, while the
effects of N70A, N70H, and P100H were not as pronounced (40-50%) of controls in females and
50-70% of controls in males).
Few data on organ weights were provided in the publication (Smith et al., 1996). The
text indicated that dose-related increases in absolute and relative liver weights were observed in
rats treated with >2000-ppm N10A, N15H, P15H, or N70A, with greater increases observed in
females than in males. In females, significant (p < 0.05) increases in relative liver weight were
also observed at 200 ppm of N15H, P15H, and N70A (data presented graphically). Increases in
liver weight persisted in the recovery groups, although the magnitude of difference was usually
less in these groups than in similarly-dosed animals evaluated at termination of exposure. In
females treated with 20,000-ppm N10A, N15H, or P15H, absolute and relative weights of
mesenteric lymph nodes were increased (p < 0.05) more than 2.5-fold over control values; these
increases also persisted in the recovery groups, while increases appeared for the first time in the
recovery groups treated with N70A or N70H. The authors indicated that there were similar
changes in male rats but that the magnitude of change was smaller. Increases in absolute and
relative spleen weight were observed in rats of both sexes treated with 20,000-ppm N1 OA,
N15H, P15H, N70A, N70H, or P70H; the increases were larger in females (+5 to 15% based on
data presented graphically) than in males (data not given) and remained after the recovery period
in females only. Relative spleen weight was also increased in females at 2000-ppm P15H (data
presented graphically). Small increases in absolute and relative kidney weights (4—10% greater
than controls) were reported in males and females treated with 20,000-ppm N1 OA, N15H, or
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P15H and in females treated with 20,000-ppm N70H. After the recovery period, there were no
statistically significant differences from controls in kidney weight.
Histopathology evaluation did not indicate any effects of treatment with P70H or P100H
(Smith et al., 1996). Treatment-related histopathological changes in the liver, consisting of
granulomas and/or microgranulomas, were observed in female rats given 20,000 ppm of N10A,
N15H, N70A, or N70H, as well as in the recovery group females given 20,000 ppm of P15H (but
not in the main study group exposed to this mixture). Granulomas were described as focal
collections of macrophages surrounded by inflammatory cells, occasional necrotic cells, and
variable fibrosis, while microgranulomas were small collections of macrophages (three to five)
with a few lymphocytes at the periphery. Granulomas and microgranulomas were observed most
frequently in the portal area and caudal lobe. The incidence of these effects was not reported;
rather, the authors reported mean severity score (see Table 6). After recovery, the severity of the
granulomas/microgranulomas was somewhat reduced, but the incidence of effects was
unchanged or increased. Focal collections of macrophages were also reported in the mesenteric
lymph nodes (usually cortical region) in male and female rats treated with N10A, N15H, P15H,
N70A, or N70H. The effects were described as histiocytosis, and a combined incidence/severity
score was assigned to each treatment group (Table 6). The incidence of minimal-to-mild
histiocytosis in control rats was 31-37%. Some attenuation of the histiocytosis was observed in
the female recovery group treated with N1 OA, N15H, or P15H, while increases in effect were
observed in recovery group males and females treated with N70A or N70H.
Effects of the mineral oils were inversely related to average molecular weight
(Smith et al., 1996). The only significant effects reported for the two higher molecular weight
oils (P70H and P100H) were 10 to 13% increases in ALT and AST, and increases in absolute
and relative spleen weight (<10% increase in relative spleen weight based on data shown
graphically). No other effects were observed with these test materials; thus, the highest dose
tested (1815 mg/kg-day in males and 1951 mg/kg-day in females) is a freestanding NOAEL for
these materials.
For the lower molecular weight oils, the high dose (1951 mg/kg-day) is a LOAEL in
F344 rats based on granulomas and/or microgranulomas in the livers of female rats. As
discussed above, the lesions observed in the mesenteric lymph nodes (microgranulomas or
histiocytosis), although more frequent in all treated animals than in controls, are not considered
adverse, but rather a marker of exposure (Fleming et al., 1998; Carlton et al., 2001; WHO, 2003).
The NOAEL is 190 mg/kg-day.
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Table 6. Mean Severity Scores for Histopathological Changes in Liver and
Mesenteric Lymph Nodes3

Dose (ppm)
Males
Females
Mesenteric Lymph
Nodesb
Liver0
Mesenteric Lymph
Nodesb
Control (Study 1)
0
7
0
27
Control-recovery (1)
0
31
3
37
Control (Study 2)
0
10
5
0
Control-recovery (2)
0
ND
ND
ND
N10A
20
5
0
45
200
10
0
125d
2000
170d
0
230d
20,000
225d
115d
310d
NIO-recovery
20,000
240d
80d
210d
N15H
20
20d
0
10
200
55d
0
110d
2000
125d
5
225d
20,000
130d
120d
235d
N15H-recovery
20,000
140d
40d
110d
P15H
20
10
0
35
200
45d
5
122d
2000
120d
10
230d
20,000
145d
30
189d
P15H-recovery
20,000
160d
80d
160d
N70A
20
10
0
35
200
5
15
85d
2000
75d
0
170d
20,000
100d
15d
160d
N70 A-recovery
20,000
250d
50d
200d
N70H
20
5
0
40
200
5
0
85d
2000
55d
0
95d
20,000
25d
20d
65d
N70H-recovery
20,000
150d
80d
150d
P70H
20
10
0
5
200
0
0
40
2000
0
30
40
20,000
0
0
0
P70H-recovery
20,000
ND
ND
ND
P100H
20
0
0
40
200
0
0
30
2000
5
0
15
20,000
0
0
25
PlOOH-recovery
20,000
40
0
50
aSmithetal., 1996
bMean severity score (1-4 for minimal-marked) multiplied by 100
°Mean severity score (lor 2 for microgranulomas and 3 or 4 for granulomas) multiplied by 100
Statistically significant difference from controls (p < 0.05)
ND = no data.
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In a recent study, Scotter et al. (2003) administered three white mineral oils (N15H,
N70H, and P70H) to female F344 rats for 28 or 90 days at dietary concentrations of 0% or 2%.
Groups of 12 animals per treatment time were used for controls and for each mineral oil. Daily
examinations for signs of toxicity, as well as detailed weekly examinations were conducted.
Body weights were measured twice weekly, and food intake was estimated for the intervening
periods. Excreta (fecal and urinary) were collected from groups of four animals designated for
tissue analysis of hydrocarbon content. At necropsy after either 28 or 90 days, blood samples
were collected from the groups of four used for tissue analysis. All animals were necropsied,
and organ weights (brain, heart, kidneys, liver, spleen, and mesenteric lymph nodes) were
recorded. In groups of eight animals/dose/time designated for histopathology examination,
mesenteric lymph nodes were also weighed; small intestine and muscle samples from the four
animals designated for tissue analysis were weighed. In the histopathology groups, microscopic
examinations of the brain, heart, kidneys, liver, mesenteric, and cervical lymph nodes, small
intestine, and spleen were performed.
Exposure to the three mineral oils was associated with significantly higher food intake
when compared with controls. Average intakes of the test materials were estimated by the
authors to be 2518, 2650, and 2608 mg/kg-day in the 28-day study and 2049, 1994, and
2116 mg/kg-day in the 90-day study for N15H, N70H and P70H, respectively
(Scotter et al., 2003). Treatment did not result in clinical signs of toxicity. The mean body
weight was significantly increased over controls (+5%) in rats treated for 28 days with N15H; no
other effects on body weight were observed. In the 28-day study, increases in absolute and
relative liver weight, as well as an increase in the absolute weight of mesenteric lymph nodes,
were noted in rats treated with N15H. In the 90-day study, treatment with N15H resulted in
significant (p < 0.0001) increases in absolute2 and relative liver weight (19 and 21% higher than
controls for absolute and relative weight, respectively), proximal and distal mesenteric lymph
node (2- to 6-fold higher) and spleen (27 and 31% higher) weights. Treatment with N70H
resulted in significant (p < 0.05) increases in absolute and relative lymph node weight and
absolute and relative spleen weight. Relative proximal and distal lymph node weight increases
were 67 and 20% above controls, while relative spleen weight was increased by 12%. Absolute
organ weights were not reported for this treatment group. No organ weight changes were
observed with P70H treatment for 90 days.
Analysis of mineral hydrocarbon content in tissues showed detectable levels of the three
mineral oils in the distal small intestine (0.72-2.87%) w/w), proximal small intestine
(0.01-0.14%)), heart (0.08-0.37%>), and kidney (0.98-2.62%>). In addition, mineral hydrocarbons
were detected in the distal and proximal mesenteric lymph nodes of animals exposed to N15H
(0.21%>) and N70H (0.03%>) oils, respectively (Scotter et al., 2003).
Statistically significant increases in the incidences of histopathology findings were
observed in animals treated with N15H and N70H, as shown in Table 7 (Scotter et al., 2003).
Histiocytosis of the proximal lymph nodes was present after 28 days of treatment with N15H
(p < 0.01); no other histopathology was evident at this sacrifice (Scotter et al., 2003).
Histiocytosis of the proximal lymph nodes was also observed after 90 days of treatment with
2The text of the paper (Scotter et al., 2003) reported that absolute liver weight was significantly increased, but the
table indicated that the difference was not statistically significant. A /-test conducted for this review indicated that
the difference was significant (p < 0.0001).
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N15H and N70H (p < 0.001). Individual cell necrosis was observed within the foci of
histiocytosis in 5/8 rats treated with N15H (p < 0.05). Treatment with N15H for 90 days also
resulted in increased incidences of total liver granulomas (minimal-to-mild severity) (p < 0.001)
and macrophage accumulation and/or vacuolation in the lamina propria of the small intestine
(p < 0.001). Calcification of the kidney medulla was observed at an increased incidence in rats
treated with N70H (p < 0.05).
Table 7. Incidence of Significant Histopathological Findings in Female Rats Treated with
Mineral Oils for 28 or 90 Daysa


Control
2% N15H
2% N70H
28-day Sacrifice
Histiocytosis of proximal mesenteric lymph nodes
0/8
6/8b
0/8
90-day Sacrifice
Histiocytosis of proximal mesenteric lymph nodes
0/8
8/8°
8/8°
Individual cell necrosis within foci of histiocytosis
0/8
5/8d
1/8
Calcification of kidney medulla
2/8
6/8
7/8d
Liver granuloma - minimal
0/8
6/8
2/8
- mild
0/8
1/8
0/8
- total
0/8
7/8°
2/8
Small intestine: macrophage vacuolation in lamina propria
0/8
7/8°
0/8
aScotter et al., 2003
V<0.01
><0.001
dSignificantly different from control, p < 0.05
There were no statistically significant increases in the incidence of microscopic findings
in rats treated with 2% P70H for 28 or 90 days (Scotter et al., 2003). Histiocytosis of the
proximal mesenteric lymph nodes was present in 2/8 rats treated with P70H for 90 days, but this
incidence was not statistically different from controls.
This study identified a LOAEL of 2049 mg/kg-day for N15H based on liver granulomas,
individual cell necrosis in foci of histiocytosis of the mesenteric lymph nodes, macrophage
vacuolation in the lamina propria of the small intestine, and possible inflammation of the cardiac
mitral valve; no NOAEL can be identified. For N70H, a LOAEL of 1994 mg/kg-day based on
increased incidence of calcification of the kidney medulla is identified. This effect was noted in
a table in the publication but not discussed in the text of the report. In another subchronic study
of N70H (Smith et al., 1996), this effect was not observed after exposure of the same strain and
sex of rat for 90 days at the same dose. However, there are no other subchronic studies and no
long-term studies of N70H to inform the question of kidney effects; thus, the dose in this study is
identified as a LOAEL. No effects were observed with P70H treatment; thus, the single dose
tested (2116 mg/kg-day) is a freestanding NOAEL.
Chronic Studies—Shoda et al. (1997) conducted a chronic study of liquid paraffin
(average molecular weight of 475, average carbon number 25, 35:65 ratio of naphthenic to
paraffinic hydrocarbons) administered in the diet to F344 rats. Groups of 50/sex/dose rats were
given the test materials at dietary concentrations of 0, 2.5, or 5% ad libitum for 104 weeks. The
animals were observed daily for mortality and clinical signs of toxicity; body weights were
measured weekly for the first 8 weeks and then monthly thereafter. Food consumption was
measured monthly and used to calculate intake of test materials. At sacrifice after 104 weeks,
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blood was collected for hematology (WBC, RBC, Hb, Hct, and platelet count), and the animals
were necropsied. Weights of the brain, submaxillary gland, lungs, heart, liver, spleen, adrenals,
kidneys, and testes were recorded. Major organs (not specified) and any tumor masses were
subjected to microscopic examination.
Treatment with the liquid paraffin did not affect survival or clinical signs of toxicity
(Shoda et al., 1997). Statistically significant increases in body weight (<5% change from
control) were observed throughout most of the study in the treated animals, and there were
corresponding increases in food consumption. Using food intake and body weight data, the
authors calculated average daily doses of 0, 962.2, and 1941.9 mg/kg-day for males and 0, 1135,
and 2291.5 mg/kg-day for females. Although the authors did not report hematology data, the
text indicated that there were no treatment-related findings. Significant increases in absolute
liver (8% higher than control,/* < 0.05) and kidney weights (10-15% higher for left and right,
p < 0.01) were noted in high-dose males. In high-dose females, the absolute and relative weights
of submaxillary glands were significantly (p < 0.05) decreased (6 and 11% below controls,
respectively).
The incidence and severity of granulomatous inflammation of the mesenteric lymph
nodes were both increased in a dose-related manner in treated animals (see Table 8)
(Shoda et al., 1997). Other nonneoplastic lesions (including microgranuloma of the liver, bile
duct proliferation, myocardial fibrosis, and chronic nephropathy) were observed but were not
considered treatment-related. There were no statistically significant differences in the incidences
of any tumor types. This study identified a freestanding NOAEL of 1941.9 mg/kg-day in males
and 2291.5 mg/kg-day in females. As noted earlier in the discussion of Baldwin et al. (1992),
granulomas of the mesenteric lymph nodes are not considered adverse (Fleming et al., 1998;
Carlton et al., 2001; WHO, 2003).
Table 8. Incidence of Granulomatous Inflammation of Mesenteric Lymph Nodes


by Severity Score3



None
1 (slight)
2 (mild)
3 (moderate)
Mean Scoreb
Males0
0
13/50
20/50
13/50
4/50
1.16
2.5%
5/50
3/50
15/50
27/50
2.28
5.0%
9/50
2/50
10/50
29/50
2.18
Females0
0
9/48
17/48
22/48
0/48
1.27
2.5%
4/50
1/50
14/50
31/50
2.44
5.0%
6/49
0/49
14/49
29/49
2.34
aShoda et al., 1997
bSum of severity scores divided by number of animals
Significant trend for increased severity with dose (p < 0.001, Jonckheere-Terpstra test performed for
this review)
Another chronic study was conducted in F344 rats fed high molecular weight white
mineral oils (P70H and P100H) in the diet for 2 years (Trimmer et al., 2004). The study,
conducted in three phases, used doses of 0, 60, 120, 240, and 1200 mg/kg-day. In the
carcinogenicity phase, 50 rats/sex/dose were treated for 24 months and sacrificed; in the chronic
toxicity phase, 10 rats/sex/dose were treated for 12 months and sacrificed. A third phase
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examined the reversibility of effects; 20 rats/sex/dose were treated for 12 months and then given
the control diet for the following 12 months prior to sacrifice. Satellite groups of 5 female
rats/dose were sacrificed at 3, 6, 12, 18, and 24 months for evaluation of hydrocarbon content of
tissues (liver, kidneys, mesenteric lymph nodes, and spleen).
All animals were examined weekly for toxicity and were palpated for masses at that time;
daily observations for signs of toxicity were also made (Trimmer et al., 2004). Body weights
and food consumption were recorded weekly for 13 weeks and monthly thereafter. Quarterly
ophthalmology examinations were performed. Blood was collected at 3, 6, 9, 12, 15, 18, 21, and
24 months for comprehensive hematology and serum chemistry evaluations; urine was collected
at 3, 6, 12, 18, and 24 months for evaluation of urine chemistry. All rats other than the satellite
groups used for tissue content analysis were necropsied. Weights of heart, kidneys, liver, spleen,
ovaries, testes, brain, adrenals, and mesenteric lymph nodes were recorded. Control and
high-dose animals in the carcinogenicity and chronic phases were subjected to comprehensive
histopathological examinations, and the lungs, liver, kidneys, mesenteric lymph nodes, and
spleen were examined in intermediate-dose groups. In the recovery-phase animals, tissues
identified as target organs in the chronic phase were examined microscopically: liver and
mesenteric lymph nodes for P70H and no organs for P100H.
Survival of the high-dose females exposed to P100H was significantly (p < 0.05) lower
than controls (data presented graphically) but was within the normal 24-month survival range for
F344 rats (Trimmer et al., 2004). No treatment-related effects on survival or clinical signs were
noted. High-dose animals of both sexes (for both test materials) had significantly higher food
consumption and body weights than controls; increased food intake was attributed to
compensation for reduced calorie intake due to substitution with mineral oil. Statistically
significant differences in hematology and clinical chemistry parameters occurred without
consistent change from control or correlation with other parameters. The study authors
characterized the observed changes as inconsequential or not biologically significant
(Trimmer et al., 2004). The absolute and relative weights of mesenteric lymph nodes were
significantly (p < 0.01) increased in females treated for 24 months with P70H (all doses) and
with the highest dose of P100H, as well as in males treated with the 1200-mg/kg-day P70H. In
the recovery groups, there were no dose-related differences from controls in lymph node
weights. There were statistically significant increases in spleen weight (up to 48%, observed at
low dose of P100H) in some treatment groups, but the change did not exhibit a dose-response
relationship. Analysis of tissues for mineral hydrocarbons showed consistently detectable levels
in the liver but not in other organs; hepatic levels reverted to near background levels in recovery
group animals assessed after 12 months on the control diet.
Histiocytosis of the mesenteric lymph nodes was observed at similar frequencies (at or
near 100%) in both treated and control groups after both 12 and 24 months of treatment
(Trimmer et al., 2004). The mean severity score for the effect was reportedly higher (mild rather
than minimal) in treated than in control rats. A statistically significant increase in the severity
score occurred in rats (both sexes) exposed to 1200-mg/kg-day P70H after 24 months and in
females exposed to all doses of P100H for 24 months. An increase in the incidence of cystic
degeneration (focal dilated vascular spaces accompanied by eosinophilic debris or necrotic
hepatocytes) and angiectasis (focal dilatation of the sinusoidal spaces) in the liver was observed
in male rats; the combined incidence of these effects was statistically significantly (p < 0.05)
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different from controls at all doses of P70H and at the high dose of P100H only. However, the
authors did not consider this effect to be biologically significant due to its common occurrence in
untreated F344 rats. The historical control incidence of the effect was not reported. In addition,
the incidence and severity of liver portal vacuoles was increased in males and females treated
with >120-mg/kg-day P70H or P100H and in males exposed to all doses of P70H; however, the
authors characterized these as markers of exposure and not toxicity. No granulomas or
microgranulomas were observed in the livers of animals treated with either mineral oil.
There were no treatment-related increases in the incidence of neoplasia (Trimmer et al.,
2004). The incidence of adenoma of the pars distalis was statistically different from controls in
females exposed to 1200-mg/kg-day P100H, but the authors reported that it was within the
historical control range for F344 rats. This study identifies a freestanding NOAEL of
1200 mg/kg-day for both P70H and P100H.
Other Studies
Other Routes
MADEP (2003) observed that emerging data suggested an association between exposure
to petroleum distillates and autoimmune diseases. The human study (Lacey et al., 1999) cited as
support for this finding was of inhalation exposure to hydrocarbon mixtures containing
10-30% aromatic content and, thus, is not adequate to suggest an association with the aliphatic
content of the mixtures. The animal studies of this association (Shaheen et al., 1999;
Richards et al., 1999, 2001) were injection studies of pristane (2,6,10,14-tetramethylpentadecane,
C19H40, a branched aliphatic component of mineral oil). The update literature search did not
identify any studies of autoimmune endpoints associated with oral or inhalation exposure to
mineral oils. The relevance of the findings of the injection studies of pristane to effects of oral or
inhalation exposure to mineral oils is uncertain given likely differences in the toxicokinetics after
injection exposure.
Toxicokinetics
The toxicokinetics of medium- and low-viscosity mineral oils were reviewed by
WHO (2003). Many of the studies on absorption, distribution and excretion were aimed at
identifying differences in toxicokinetics between F344 rats, which are particularly sensitive to
the effects of mineral oils, and Sprague-Dawley rats, which are not sensitive. These unpublished
toxicokinetics studies using [l-14C]-l-eicosanylcyclohexane as a tracer suggest that mineral oil
is absorbed to some extent across the gastrointestinal tract and that the primary route of excretion
is fecal (up to 94% of administered radioactivity after 96 hours), with urinary elimination
accounting for <10% of administered dose (as reviewed by WHO, 2003). The studies confirmed
that F344 rats absorb more mineral oil and excrete it at a slower rate than Sprague-Dawley rats.
This finding is consistent with the results of tissue analyses for hydrocarbons during the toxicity
study by Firriolo et al. (1995), which indicated that, at equal doses, there was greater deposition
of hydrocarbons in liver, lymph nodes and other tissues of F344 rats than in other rat strains.
Immunotoxicity
An unpublished study performed by ImmunoTox was described by WHO (2003); a
preliminary report of this study, with few details included, was provided to U.S. EPA under
Toxic Substance Control Act Section 8(e) (Equiva Services, 2000). The study description
included herein is drawn from information provided by WHO (2003), because the microfiche
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(Equiva Services, 2000) contained only preliminary results. The study, conducted in two phases,
exposed groups of eight (per strain) female F344 and Sprague-Dawley rats to PI 5 mineral oil in
the diet at concentrations of 0, 0.02, or 2.0% (F344) or 0, 1.0, or 2.0% (Sprague-Dawley). In the
first phase, exposure continued for 90 days; in the second phase, exposure continued for
120 days followed by a 30-day recovery period. Body weights and food consumption were
measured for the first 90 days of each study. Immune response to sheep erythrocyte sensitization
was assessed as IgM response in a modified hemolytic plaque assay on the day of sacrifice
(Day 91) in Phase I. In Phase II, IgM antibody titers after dinitrophenol-human serum albumin
challenge were measured on Day 91, and the response observed was used to determine whether
to continue the study. The latter immune sensitization was repeated on Days 115 and 121, and
IgG was measured. A final sensitization with sheep erythrocytes occurred on Day 147 followed
by sacrifice on Day 151 for IgM determination in the spleen. Upon sacrifice, brain, liver, spleen,
and lymph node weights were recorded, and liver, mesenteric lymph nodes (with adipose tissue)
and spleen (Sprague-Dawley only) were examined histopathologically.
Body weights and food consumption rates were not affected by treatment. Absolute and
relative liver weights were significantly (p-value not reported) increased over control values in
Sprague-Dawley rats at both dose levels and to the same general degree; no data were reported
by WHO (2003). In F344 rats, statistically significant, dose-related increases in absolute and
relative liver weights were observed after 90 days; relative liver weight remained increased after
120 days treatment and 30 days recovery. Spleen and mesenteric lymph node weights of
F344 rats were increased at the high dose in both phases. Histopathology after 90 days exposure
revealed granulomatous inflammation of the mesenteric lymph nodes in all control and treated
F344 rats (6/8, 8/8, and 8/8 for control, low-, and high-dose, respectively), with increased
severity at the high dose. F344 rats exposed for 90 days also exhibited granulomatous
inflammation of the liver (0/8, 1/8, 7/8). Inflammation of both lymph nodes and liver persisted
in the animals exposed for 120 days followed by 30 days recovery. In Sprague-Dawley rats,
minimal granulomatous inflammation of the mesenteric lymph nodes occurred in nearly all
treated animals (1/16, 15/16, and 15/16 for control, low-, and high dose, respectively); Phase II
animals of this strain were sacrificed after 90 days due to the lack of IgM response.
Immunotoxicity testing showed no effect on spleen IgM response in Sprague-Dawley rats
(as reviewed by WHO, 2003). In contrast, a dose-dependent reduction in antibody-forming cell
response (when expressed per 106 spleen cells) was observed in F344 rats; the decrease was
statistically significant at the high dose. Because the number of spleen cells was increased at the
high dose, no difference from controls was recorded when the results were reported on the basis
of total spleen activity. The immunologic effects persisted in the F344 group exposed for
120 days followed by a 30-day recovery period.
Neither WHO (2003) nor Equiva Services (2000) provided dose estimates associated
with the dietary concentrations of P15H administered in this study. Based on information from
other studies using P15H and these strains of rats (Firriolo et al., 1995; Smith et al., 1996), the
doses are estimated to be in the range of 200 and 2000 mg/kg-day (0.2% and 2.0%). This study
suggests that immunologic effects and granulomatous inflammation of the liver are observed
only at the higher concentration; however, effect levels cannot be determined from this study due
to the lack of data.
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Relevance of Animal Pathology to Humans
Fleming et al. (1998) compared the morphology of granulomas identified in the lymph
nodes, spleen, liver, and bone marrow of long-term human mineral oil users with those observed
in the lymph nodes and liver of F344 rats treated with mineral oils and waxes. Lipogranulomas
observed on autopsy of human mineral oil users were described as collections of oil or lipid
droplets, frequently found in macrophages and forming both micro and macrovesicles.
Occasionally, multinucleated giant cells were present, as well as lymphocytes and plasma cells in
varying amounts. The aggregation of these cells was termed a lipogranuloma. The authors
noted that scarring fibrosis occurred rarely. In contrast to the lipogranulomas in humans, liver
lesions in F344 rats were characterized as follicular epithelioid granulomas. These were
collections of epithelioid macrophages (enlarged macrophages with eosinophilic cytoplasm,
indistinct cell borders and vesicular eccentric nuclei, resembling epithelial cells) with frequent
multinucleated cells, lymphocytes and fibrosis. The authors concluded that there were no
morphological similarities between the lipogranulomas observed in humans and the liver lesions
developed in F344 rats, in that the rat lesions were epithelioid, with extensive inflammation and
some necrosis, while the human lesions were histiocytic collections with minimal inflammation.
The authors postulated that the different morphology reflected the relative balance between
T helper 1 and T helper 2 responses to mineral oil and the different cytokines generated by these
lymphocytes. With respect to the lymph node lesions, Fleming et al. (1998) characterized these
as focal accumulations of vacuolated macrophages, with no evidence of inflammation or cell
damage.
A panel of experts convened to examine the question of whether the lymph node and
hepatic lesions in F344 rats were relevant to humans drew a similar conclusion to that of
Fleming et al. (1998). Publishing the results of a pathology workshop on this issue at the
Fraunhofer Institute of Toxicology and Aerosol Research in Germany, Carlton et al. (2001)
concluded that the lesions in F344 rats differed morphologically from those in humans and that
the lipogranulomas observed in the liver, spleen, and lymph nodes of humans were "incidental
and inconsequential." With respect to the F344 rat, lymph node granulomas were considered to
have little or no biological significance, while the liver granulomas, which include inflammatory
and occasionally necrotic components, represented an adverse effect of mineral oil exposure in
that strain of rat (Carlton et al., 2001).
Genotoxicity
No information regarding the genotoxicity of white mineral oils was located.
DERIVATION OF PROVISIONAL SUBCHRONIC AND CHRONIC
ORAL RfD VALUES FOR MINERAL OIL
Mineral oils of lower molecular weight (<480) and carbon range are most pertinent to the
C9-C32 fraction. These include N10A, N15H, P15H, N70A, and N70H, tested by Smith et al.
(1996); Marcol 72, Marcol 82, and EZL 600, tested by Smith et al. (1995); P15H tested by
Firriolo et al. (1995); and N15H and N70H tested by Scotter et al. (2003). In contrast, the carbon
range of higher molecular weight mineral oils (EZL 550 tested by Smith et al. 1995, and P70H
and P100H tested by Smith et al., 1996, Scotter et al., 2003, and Trimmer et al., 2004) includes a
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significant proportion of compounds outside the C9-C32 range. Similarly, the liquid paraffin
tested by Shoda et al. (1997) had physical properties (viscosity, molecular weight and ratio of
naphthenic:paraffinic hydrocarbons) similar to P70H and, thus, is not considered relevant to the
C9-C32 fraction. Baldwin et al. (1992) provided no information on the mineral oils tested
(OTWO and HTWO) other than viscosity and specific gravity. Thus, it is difficult to determine
whether the data are relevant to the C9-C32 fraction or not, so they are not included in the
assessment. The data considered relevant to the derivation of provisional oral toxicity values for
mineral oil as a surrogate for the C9-C32 fraction are from studies using the lower molecular
weight/lower carbon range mineral oils listed above. Overviews of the pertinent animal studies
are given in Table 9. Studies of mineral oil effects based on treatment-related exposures in
humans (Clark et al., 1987; Gal-Ezer and Shaoul, 2006; NASPGHN, 2006 Speridiao et al., 2003;
Urganci et al., 2005) are also given in Table 9.
The animal database of mineral oil studies relevant to the C9-C32 fraction includes only
subchronic toxicity studies. As Table 9 shows, the effects observed in most of the animal studies
and at the lowest doses were liver granulomas in F344 rats. Available information indicates that
these lesions occur in F344 but not other rat strains (Firriolo et al., 1995; Smith et al., 1995),
possibly because the F344 rat tends to absorb and retain mineral oil constituents to a greater
degree than other rat strains (as reviewed in WHO, 2003). While liver granulomas have been
noted upon autopsy of human mineral oil users, these lesions appear to differ morphologically
from those observed in F344 rats (Fleming et al., 1998; Carlton et al., 2001) and to be of little
toxicological consequence in humans (Carlton et al., 2001). However, the available data are not
adequate to determine conclusively whether or not the lesions observed in F344 rats are relevant
to humans. No data exist to characterize the doses of mineral oil received by the humans in
whom lesions were observed nor the durations of use. Consequently, it is not possible to
determine whether the inflammatory lesions observed in the rats could occur in humans at higher
doses or over a longer duration of exposure. Further, while there are data reviewed by WHO
(2003) showing clear differences in the toxicokinetics of mineral oil in F344 rats compared with
Sprague-Dawley rats, there are no data to suggest whether the F344 or the Sprague-Dawley
strain of rat is a better model for mineral oil absorption, distribution, metabolism, excretion, and
toxicological response in humans.
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Table 9. Summary of Oral Noncancer Dose-Response Information for Mineral Oils Pertinent to the C9-C32
Aliphatic Fraction3
Mixture or
Compound
Species
and Sex
Dose
(mg/kg-day)
Exposure
Regimen
NOAEL
(mg/kg-
day)
LOAEL
(mg/kg-day)
Responses at
the LOAEL
Comments
Reference
Mineral oil
Human
>1 year of
age (m/f)
870-2600
Daily
maintenance
dose
870-2600
NA
NA
Laxative effects. Side effects
noted include foreign-body
reaction in intestinal mucosa.
Maintenance dose for
treatment of constipation.
Human therapeutic experience.
NASPGHN, 2006
Mineral oil
Human
children
2-14
years old
(m/f)
2250
(weighted
average)
Daily
treatment,
decreasing
doses, for 4
months
2250
NA
NA
Laxative effects; decrease in
serum (5-carotene levels.
Endpoints included only serum
levels of retinol, B-carotene,
and a-tocopherol.
Clark etal., 1987
Mineral oil
Human
children
2-12
years old
(m/f)
870
Daily for 90
days
870
NA
NA
Laxative effects; slight
improvement in
anthropometric measures.
Endpoints included only
anthropometric measures.
Speridiao et al., 2003
Mineral oil
Human
children
2-12
years old
(m/f)
1600
Daily for 8
weeks
1600
NA
NA
Laxative effects; watery stools.
Endpoints included only
symptom control and
compliance with treatment.
Urganci et al., 2005
Mineral oil
Human
female =
17 years
old (f)
348,000
Daily for 5
months
348,000
NA
NA
No effects on physical exam.
Serum levels of fat-soluble
vitamins (A and E), calcium,
phosphorus, alkaline
phosphatase (as measures of
vitamin D status), and
prothrombin time (as a
measure of vitamin K status)
were within normal limits.
Gal-Ezer and Shaoul,
2006
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Table 9. Summary of Oral Noncancer Dose-Response Information for Mineral Oils Pertinent to the C9-C32
Aliphatic Fraction3
Mixture or
Compound
Species
and Sex
Dose
(mg/kg-day)
Exposure
Regimen
NOAEL
(mg/kg-
day)
LOAEL
(mg/kg-day)
Responses at
the LOAEL
Comments
Reference
Marcol 72
(C14-C38),
Marcol 82
(C16-C34),
EZL 600
(C20-C36)
Long-
Evans
Rats (m/f)
0, 21, 108 (m)
and
0, 25, 125 (f)
Diet for 13
weeks
108 (m)
125(f)
NA
NA

Smith et al., 1995
N10A
(C15-C30),
N15H
(C17-C30),
P15H
(C18-C30),
N70A
(C21-C35),
N70H
(C22-C37)
F344 rats
(m/f)
0, 1.7, 17, 173,
1815 (m) and
0, 2.0, 19, 190,
1951 (f)
Diet for 90
days
190
1951 (f)
Liver
granulomas
and micro-
granulomas in
females
No granulomas or
microgranulomas were
observed in males.
Histiocytosis in mesenteric
lymph nodes not considered
adverse.
Smith et al., 1996
P15H
(C18-C30)
F344 (f)
0, 161, 1582
Diet for 92
days
NA
161
Micro-
granulomas of
liver.
Incidence of microgranulomas
increased with both dose and
time.
Firriolo et al., 1995
P15H
(C18-C30)
Crl: CD (f)
0, 158, 1624
Diet for 92
days
158
1624
Multifocal
chronic
inflammation
of liver

Firriolo et al., 1995
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Table 9. Summary of Oral Noncancer Dose-Response Information for Mineral Oils Pertinent to the C9-C32
Aliphatic Fraction3
Mixture or
Compound
Species
and Sex
Dose
(mg/kg-day)
Exposure
Regimen
NOAEL
(mg/kg-
day)
LOAEL
(mg/kg-day)
Responses at
the LOAEL
Comments
Reference
N15H
(C17-C30),
N70H
(C22-C37)
F344 (f)
0, 2049
(N15H), 1994
(N70H)
Diet for 90
days
NA
2049 (N15H)
1994 (N70H)
Liver
granuloma;
individual cell
necrosis in
foci of lymph
node
histiocytosis,
macrophage
vacuolation of
small intestine
(N15H only);
calcification
of kidney
medulla
(N70H)

Scotter etal., 2003
aDose conversions have been undertaken and presented in this Table to characterize doses in mg/kg-day (instead of mL/kg-day) so the reader can compare across
studies using the following calculations. The specific gravity of white mineral oil is 0.83-0.905; HSDB (2007). Using the midpoint of the range (0.87) and the
density of water (1000 mg/mL), a dose of 1 mL/kg-day is calculated to deliver 870 mg/kg-day (1 mL/kg-day x 0.87 x 1000 mg/mL), and a dose of 3 mL/kg-day
is calculated to deliver 2600 mg/kg-day (3 mL/kg-day x 0.87 x 1000 mg/mL).
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In addition to animal studies of various mineral oils, available information on the
potential toxicity of hydrocarbons in this fraction includes human therapeutic experience with
oral mineral oil treatment for chronic constipation. Current recommendations for maintenance
doses of mineral oil to treat chronic constipation in children (>1 year of age) are 1-3 mL/kg-day,
or 870-2600 mg/kg-day (NASPGHN, 2006). Based on the few studies of mineral oil treatment
in humans (Clark et al., 1987; Gal-Ezer and Shaoul, 2006; Speridiao et al., 2003; Urganci et al.,
2005), side effects are few and minor. While none of the references specified a recommended
duration of treatment, one study cited by Clark et al. (1987) involved treatment for up to 6 years.
Given the uncertainty in the relevance of the liver lesions observed in F344 rats and the
substantial clinical experience behind the human therapeutic dose range, the provisional oral
toxicity values for mineral oil were estimated using the lower end of the human therapeutic dose
range as the point of departure (POD). The lower end of the therapeutic range (1 mL/kg-day, or
870 mg/kg-day) was regarded as a NOAEL, as the laxative effects were therapeutic and side
effects were few. Since the longest duration of treatment cited in the available studies was less
than 7 years, the exposure duration associated with the POD was assumed to be subchronic
(U.S. EPA, 2002).
A composite UF of 30 was applied to the subchronic NOAEL (870 mg/kg-day) to derive
a subchronic p-RfD. The subchronic p-RfD for mineral oil is derived as follows:
Subchronic p-RfD = NOAEL UF
= 870 mg/kg-day ^ 30
= 30 or 3 x 101 mg/kg-day
The composite UF of 30 was composed of the following:
•	An UF of 3 (10°5) for intraspecies differences was used. The POD represents the
lower end of the therapeutic range and, thus, should provide some protection for
potentially sensitive individuals. In addition, the therapeutic range of doses is
recommended for children as young as 1 year of age, a population that may be
more sensitive than adults. Although these factors argue for a lower intraspecies
UF, an UF of 1 was not considered, because there are no data with which to
identify potentially sensitive subpopulations. While Gal-Ezer and Shaoul (2006)
observed no effects in an individual exposed to 348,000 mg/kg-day for 5 months,
this was a case report of only one person. More sensitive individuals may have
other responses to such an exposure. In addition, it is possible that individuals
(adults or children) who experience adverse responses to mineral oil treatment for
constipation switch to readily available alternative treatments, such that the
available data on health effects of mineral oil use could be skewed toward
individuals who are less sensitive. Further, there is evidence that certain strains of
rat (F344) are more sensitive to potentially adverse effects of mineral oil exposure
than other strains due to toxicokinetic differences. There is no information to
address whether there are subpopulations of humans in whom the disposition of
mineral oil is similar to that of the F344 rat.
•	A database UF of 10 was applied. There is a lack of data on developmental and
reproductive toxicity. Absence of any of these studies contributes to database
uncertainty. Further, despite the extensive human clinical experience with
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mineral oil use, there are few data evaluating potential subclinical effects of
mineral oil exposure and no epidemiological data on effects of mineral oil use.
The few human studies of mineral oil exposure (Clark et al., 1987; Speridiao et
al., 2003; Urganci et al., 2005; Gal-Ezer and Shaoul, 2006) have evaluated limited
endpoints in small numbers of individuals. The possible association between
mineral oil constituents and autoimmune disorders, suggested by injection studies
in rodents, merits further investigation and contributes to the database uncertainty.
In addition, there remains uncertainty as to the potential relevance of the rat liver
granulomas to effects in humans, as potential immunological effects in humans
have not been examined. These uncertainties, coupled with the lack of data on
developmental and reproductive toxicity, warrant the use of a 10-fold UF for
database deficiencies.
To derive the chronic p-RfD, an additional 10-fold UF for exposure duration was applied
to the POD, resulting in a total UF of 300. None of the available human studies of mineral oil
provided any information on chronic exposure to mineral oil. The chronic p-RfD for mineral oil
is derived as follows:
Chronic p-RfD = NOAEL UF
= 870 mg/kg-day ^ 300
= 3 or 3 x 10° mg/kg-day
Confidence in the POD, derived from the therapeutic dose range (NASPGHN, 2006) is
medium. While the clinical experience with mineral oil is strong, few rigorous studies of
long-term mineral oil use were available to support the recommendations, and no clear
parameters for treatment duration were identified. Confidence in the database is low. There are
inadequate data on the relevance of the animal data to toxicity in humans, and there are no data
on reproductive or developmental toxicity of mineral oils. Low confidence in the subchronic and
chronic RfDs follows.
DERIVATION OF PROVISIONAL SUBCHRONIC AND CHRONIC
INHALATION RfC VALUES FOR MINERAL OIL
Available data on inhalation of mineral oil are limited to mineral oil mists generated
during machining operations; these data are not relevant to environmental releases, which are
unlikely to generate aerosol formation. As a result, provisional inhalation toxicity values were
not derived.
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PROVISIONAL CARCINOGENICITY ASSESSMENT FOR
MINERAL OIL
Weight-of-Evidence Classification
Under EPA's Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), there is
"Inadequate Information to Assess the Carcinogenic Potential of Mineral Oils'' Despite the
long history of therapeutic mineral oil use in humans, there are no epidemiological studies
examining cancer incidence in humans exposed to mineral oils over prolonged periods of time.
In addition, there are no chronic studies of low and medium molecular weight mineral oils in
animals. Treatment-related increases in tumors have not been observed in any of the subchronic
studies, although detection of carcinogenicity in such studies is unlikely. In one chronic rat
dietary study of higher molecular weight mineral oil (Trimmer et al., 2004), the only statistically
significant difference in tumor incidence was an increased incidence of adenoma of the pars
distalis in female rats exposed to 1200-mg/kg-day P100H; however, the incidence at this dose
was within the historical control incidence for F344 rats in NTP studies. In a second chronic rat
dietary study of higher molecular weight mineral oil (Shoda et al., 1997), there were no
treatment-related increases in the incidence of any tumor type. There are no chronic bioassays of
mineral oils in any species other than the rat. Genotoxicity data for mineral oils are not
available.
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