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Abstract for MG96003

Immunotoxicity of Nonylphenol (Endocrine Disruptor) in Male and Female Sprague-Dawley Rats

CASRN: 84852-15-3
Molecular Weight: 93.1045

Abstract

The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009. The findings and conclusions for this study should not be construed to represent the views of the NTP or the U.S. Government.

Although sporadic effects were observed at lower dose levels, the most consistent effects on the immune response were observed at the 2000 ppm dose level in the F0 generation female and F1 generation male and female animals.

Nonylphenol, an endocrine disruptor, is a polyethoxylated nonylphenol (NP) which is used extensively as a non-ionic detergent surfactant in industrial applications, and undergoes biodegradation during sewage treatment to persistent metabolites, including NP and di- and monethoxylated NP. Nonylphenol was first reported to have estrogenic activity based on its induction of proliferation and up-regulation of the progresterone receptor in human estrogen-sensitive breast tumor cells (Soto et al., 1991, White et al., 1994). Estrogens are potent regulatory factors for many developmental and physiological responses. Untimely exposure to natural or synthetic estrogenic compounds may have serious consequences to the reproductive cycle in humans and animals (Korah, 1993; Ginsburg 1994). The immunological evaluation of nonylphenol-exposed animals was undertaken by the National Toxicology Program/NIEHS in cooperation with the National Center for Toxicological Research (NCTR).

Nonylphenol is one of five endocrine disruptor compounds nominated by the National Toxicology Program (NTP) for reproductive assessment studies, neurotoxicological and immunotoxicological studies, and cancer bioassay studies. The title of this project is "Effects of Endocrine Disrupting Chemicals on Fertility and Reproductive Tract Cancers". These studies were carried out as an interagency agreement between National Environmental Health Science (NIEHS) and National Center for Toxicology Research (NCTR) with the immunotoxicological component being a portion conducted outside of the NCTR facility in Jefferson, Arkansas. Thus, the purpose of these reported studies was to determine the potential effects of nonylphenol on the immune system. The nonylphenol/immunotoxicology code identification from the National Center for Toxicological Research is E2125.14.

The exposure times and the doses, 0, 25, 500 and 2000 ppm, were determined by NCTR. Nonylphenol was procured and administered in feed by personnel at NCTR in Jefferson, Arkansas. The control rats received casein NIH-31C as the feed. The studies were conducted in male and female Sprague Dawley rats, strain 23 CD, from the NCTR breeding colony. The F0 generation female rats received the test article for 65-72 days beginning 7 days into gestation. The F1 generation male and female rats received the test article in utero for 14 days and continued postpartum until 77-82 days. On the day of sacrifice, whole spleens or flushed bone marrow cells were placed in tubes with the appropriate medium, packed in wet ice, and shipped to the Medical College of Virginia (MCV) Campus of Virginia Commonwealth University, Richmond, VA, for assay evaluation on the following day. The assay days of the study were conducted between 9 April 1998 and 19 May 1998

The baseline toxicology studies are summarized in Table ES-1. Exposure to nonylphenol resulted in a statistically significant decrease in terminal body weight, both in the F0 generation female and F1 generation female rats. A decrease of 13% (F0 female) and 16% (F1 female) as compared to the vehicle controls was observed at the highest dose of 2000 ppm.

Exposure to nonylphenol resulted in a statistically significant increase in the relative spleen weight (% body weight) in the F1 generation male and female rats. The increase at the high dose only, 2000 ppm, was 15% and 17%, respectively. In the F1 generation female rat study, a significant increase in relative thymus weight was observed at the 25 ppm (21%) and 2000 ppm (25%) doses.

The F1 generation male and female rats were evaluated for nonylphenol exposure effects on bone marrow cell number, colony-forming units, CFU-E (recombinant erythropoietin), CFU-GM (granulocyte-monocytes progenitors) and CFU-M (macrophage progenitors) and DNA synthesis. A statistically significant decrease of 29% in CFU-E/2 x 105 cells was seen in the F1 generation male rats at 2000 ppm. With the F1 generation female rats, a significant increase in the CFU-GM/1 x 105 cells of 25% was observed at the high dose along with an increase of 34% in the DNA synthesis.

Table ES-2 summarizes the immunology studies. For the F0 generation female rats exposed to nonylphenol, referring to the absolute values of the splenic differential, no alteration in numbers were observed. In the F1 generation male rats, statistically significant increases were seen at the high dose in the spleen cell number (38%), B cells (47%), T suppressor cells (39%) and the macrophage cells (50%). For the F1 generation female rats, statistically significant increases were observed in the T cells, T helper cells and the macrophages, in the middle doses ranging from 38 to 50%.

In the spleen antibody-forming cell (AFC) response to T-dependent antigen, sheep erythrocytes, no alterations were observed in the F0 generation female rats nor the F1 generation male and female rats.

No effect was seen in receptor-mediated proliferation in the F0 generation female rats stimulated with anti CD3. In spleen cells from F1 generation male and female rats, stimulation with the anti-CD3 receptor-mediated proliferation produced a statistically significant dose-dependent increase in proliferation of the unstimulated spleen cells from 44 to 92% and in the stimulated spleen cells from 23 to 69% as compared to the vehicle control.

In the F0 generation female rats and the F1 generation male rats, no statistically meaningful alterations were observed in natural killer cell activity. In the F1 generation female rats, a statistically significant increase was demonstrated only at the 200:1 effector-to-target (67%) 2000 ppm dose group which was not supported by the lytic unit/107 cells. However, the lytic units per spleen were significantly increased up to 112%.

Nonylphenol, when administered in the feed at closes of 25, 500, and 2000 ppm, produced a measurable decrease in terminal body weight at the 2000 ppm dose. The results from the immunotoxicological evaluation demonstrated that nonylphenol exposure did not impact on the immunocompetence of the F0 generation female rats. However, for the F1 generation male and female rats, exposure to nonylphenol for 77 days resulted in minimal increases in T cell numbers and marked increases in T cell function.

Studies

Table ES-1
Summary Table for Toxicology Studies
E2125.14 (Nonylphenol)
Parameter Result Maximum Effect Dose Comments
Body Weights Decrease (F0 F) 13% 2000 ppm
No Effect (F1 M) 13%
Decrease (F1 F) 16% 2000 ppm
Organ Weights/F0 Female
- Spleen No Effect
- Thymus No Effect
Organ Weights/F1 Male
- Spleen No Effect 15% 2000 ppm % Body Wgt
- Thymus No Effect
Organ Weights/F1 Female
- Spleen Increase 17% 2000 ppm % Body Wgt
- Thymus No effect 25% 2000 ppm % Body Wgt
Bone Marrow/F1 Male
- Cells/Femur (x106) No effect
- CFU-GM/1x105 cells No effect
- CFU-GM/Femur (x104) No effect
- CFU-M/1x105 cells No effect
- CFU-M/Femur (x104) No effect
- CFU-E/2x105 cells Decrease 29% 2000 ppm
- CFU-E/Femur (x104) No effect
- DNA Synthesis Decrease 18% 25 ppm Not Biologically
Meaningful
Bone Marrow/F1 Female
- Cells/Femur (x106) No effect
- CFU-GM/1x105 cells Increase 25% 2000 ppm
- CFU-GM/Femur (x104) No Effect
- CFU-M/1x105 cells Decrease 11% 500 ppm No Biologically
Meaningful
- CFU-M/Femur (x104) No effect
- CFU-E/2x105 cells No Effect
- CFU-E/Femur (x104) No effect
- DNA Synthesis Increase 34% 2000 ppm



Table ES-2
Summary Table for Immunology Studies
E2125.14 (Nonylphenol)
Parameter Results Maximum Effect Dose Comment
Surface Markers (Absolute Values)
OX-33+
(B cell, CD45+)
No Effect
Increase
No Effect
F0 F
47% (F1 M)
F1 F

2000 ppm
OX-19+
(Pan T cell, CD5+)
No Effect
No Effect
Increase
F0 F
F1 M
38% (F1 F)


500 ppm
OX-38+OX-19+
(C4+, CD5+)
No Effect
No Effect
Increase
F0 F
F1 M
40% (F1 F)


500 ppm
OX-8+OX-19+
(CD8+, CD5+)
No Effect
Increase
No Effect
F0 F
39% (F1 M)
F1 F

2000 ppm
NKR-P1A+CD-8+
(NK cell)
No Effect
No Effect
No Effect
F0 F
F1 M
F1 F
HIS36+
(macrophages)
No Effect
Increase
Increase
F0 F
50% (F1 M)
50% (F1 F)

2000 ppm
25 ppm
IgM Humoral Immune Response to Sheep Erythrocytes
IgM AFC/106 Cells No Effect
No Effect
No Effect
F0 F
F1 M
F1 F
IgM AFC/Spleen No Effect
No Effect
No Effect
F0 F
F1 M
F1 F
Anti-CD3 Stimulation
Unstimulated No Effect
Increase
Increase
F0 F
60% (F1 M)
92% (F1 F)

2000 ppm
500 ppm
Stimulated No Effect
Increase
Increase
F0 F
69% (F1 M)
37% (F1 F)

500 ppm
500 ppm
Spleen Cells x 107 No Effect
Increase
No Effect
F0 F
38% (F1 M)
F1 F

2000 ppm
NK Cell Activity
200:1 No Effect
No Effect
Increase
F0 F
F1 M
67% (F1 F)


2000 ppm
100:1 Decrease
No Effect
No Effect
16% (F0 F)
F1 M
F1 F
25 ppm
50:1 No Effect
No Effect
No Effect
F0 F
F1 M
F1 F
25:1 Decrease
No Effect
No Effect
22% (F0 F)
F1 M
F1 F
25 ppm
12.5:1 No Effect
No Effect
No Effect
F0 F
F1 M
F1 F
6.25:1 No Effect
No Effect
Increase
F0 F
F1 M
60% (F1 F)


2000 ppm
LU 107 Cells No Effect
No Effect
No Effect
F0 F
F1 M
F1 F
LU/Spleen No Effect
No Effect
Increase
F0 F
F1 M
112% (F1 F)


2000 ppm