# Presentation: 529258

## Perfluorooctane Compounds in the Environment:PFOS Toxicity Studies

- Christopher Lau
- Reproductive Toxicology Division
- National Health and Environmental Effects Research Laboratory
- Office of Research and Development
- U.S. Environmental Protection Agency

## Perfluorinated organic chemicals in the news

**Perfluorinated organic chemicals in the news**

## CF3(CF2)6CF2-S-O-   K+ 

**Perfluorooctane Sulfonate (PFOS)**

## Electrochemical Fluorination

## Telomerization

**Telomerization**

## Some Commercial Uses of PFOS

- Fabric coatings
- Carpet coatings
- Paper coatings
- Floor polish
- Alkaline cleaners
- Denture cleaners
- Shampoos

- Fire-fighting foam
- Aviation hydraulic fluid
- Mining/oil well surfactant
- Acid rust suppressant
- Metal plating
- Electronic etching bath
- Ant/roach insecticides

## Environmental Exposure Profile: Human

- Detection by LC/MS to lower limit of ppb

*Olsen et al.  (1999)  J. Occup. Environ. Med. 41: 799.*
*Olsen et al.  (2001)  3M Epidemiology Report.*

| Sources | Serum Levels (ppb) |
| --- | --- |
| Production workers | 300-8,000  (2,500) |
| Non-production employees | 28-96  (47) |
| Human serum samples | 7-82 (28) |
| Blood bank pools | 9-56   (30) |
| Children | 7-515  (44) |

## Environmental Exposure Profile: Wildlife

| Sources | Liver (ppb) | Plasma (ppb) |
| --- | --- | --- |
| Marine mammals
(seal/dolphin) | 400-500 | 10-100 |
| Fresh water mammals
(otter/mink) | 300-2600 | -- |
| Birds | 400-600 | 400-500 |
| Fish | 50-100 | -- |
| Turtles and Frogs | 200-300 | 100 |
| Polar bears | 180-680 | -- |

*Giesy and Kannan (2001)  Environ Sci Technol 35: 1339; Kannan et al. (2001)  Environ Sci Technol 35: 1593; Kannan et al. (2001)  Environ Sci Technol 35: 3065; Giesy and Kannan (2002) Environ Sci Technol 36: 146A.*

## Pharmacokinetics and Distribution

- Well absorbed orally (95% within 24 h)
- Distributed mainly in serum and liver
- Not metabolized
- Fecal and urinary excretion

***Rat***: 	Plasma t1⁄2 = 7.5 days
***Monkey***: Serum t1⁄2 =  200 days
***Human***:  Estimated Serum t1⁄2 =  ~8.7 years

## Agency Concerns for Fluorinated Chemicals

- Presence of chemical is widespread in humans as well as in wildlife
- The chemical is stable, bio-persistent and bio-accumulative
- Levels detected in children are relatively high and developmental toxicity has been reported in laboratory animal model
- Modes and mechanisms of toxicity are not well defined
- Regulatory action of chemical is pending, but substitutes are being developed and marketed

## Experimental Design

**PFOS**
- Potassium salt, Fluka/3M, oral gavage daily
- Prepared in 0.5% Tween-20 Vehicle
**Animal Models**
- Sprague-Dawley rat:
-       GD 2-21, 1, 2, 3, 5, 10 mg/kg
- CD-1 mouse:
- 	   GD 1-18, 1, 5, 10, 15, 20 mg/kg

## Maternal toxicity

Developmental toxicity
Prenatal evaluation
Postnatal evaluation

Mechanisms of pathophysiology

**Developmental toxicity**
- Prenatal evaluation
- Postnatal evaluation
**Mechanisms of pathophysiology**

## PFOS levels in Pregnant Rat

## Maternal Weight: Rat

## Serum Thyroid Hormones in Pregnant Rat

## PFOS Levels in Mouse at Term

## Maternal Weight: Mouse

## Maternal Liver Weight: Mouse

**Liver Weight**

**Relative Liver Weight**

## Summary of Maternal Data

- Exposure to PFOS during pregnancy led to a reduction of maternal weight gain in both the rat and the mouse.  These deficits corresponded to administered doses and body burden of the chemical.
- PFOS treatment led to a significant reduction of circulating thyroid hormones in the pregnant rat.
- Prominent increases in maternal liver weight were seen in the mouse exposed to PFOS.

## Developmental Findings: Rat

## Notable Malformations in Rat Fetuses at Term

|  | Control | 1 mg/kg | 2 mg/kg | 3 mg/kg | 5 mg/kg | 10 mg/kg |
| --- | --- | --- | --- | --- | --- | --- |
| Cleft Palate % | 0 | 9  9 | 14  14 | 10  10 | 0 | 60  13 |
| # Sternal Defects/f | 1.2  0.3 | 1.7  0.3 | 2.1  0.3 | 2.6  0.2 | 2.1  0.2 | 3.4  0.4 |
| Anasarca % | 0 | 0 | 0 | 18  9 | 17  8 | 44  12 |
| Large rt atrium % | 0 | 2  2 | 8  8 | 0 | 23  7 | 9  4 |
| Vent. sep.
defect % | 0 | 0 | 0 | 0 | 13  6 | 15  5 |

## Developmental Findings: Mouse

## Notable Malformations in Mouse Fetuses at term

|  | Control | 1 mg/kg | 5 mg/kg | 10 mg/kg | 15 mg/kg | 20 mg/kg |
| --- | --- | --- | --- | --- | --- | --- |
| Cleft Palate % | 0 | 0 | 0 | 2  2 | 21  8 | 73  12 |
| # Sternal Defects/f | 0.5  0.1 | --- | --- | 2.1  0.2 | 2.6  0.2 | 3.3  0.7 |
| Large rt atrium % | 0 | --- | --- | 26  8 | 23  7 | 35  9 |
| Vent. sep.
defect % | 2  2 | --- | --- | 5  3 | 5  3 | 30  16 |

## Summary of Prenatal Evaluation

*In utero* exposure to PFOS did not significantly alter the implantation, nor the viability and weight of the fetus at term.
- A few structural malformations were noted, but only at the highest PFOS doses where maternal effects were indicated.

## Postnatal Survival: Rat

## PFOS levels in Developing Rat

**Serum**

**Liver**

## Body Weight of Developing Rat

## Developmental landmark: 

**Eye opening**

**Rat**

## Neonatal Serum Hormones: Rat

## Postnatal Survival: Mouse

## Developmental landmark: 

**Eye opening**

**Mouse**

## Summary of Postnatal Evaluation

- While all rats and mice were born alive, postnatal survival was severely compromised by exposure to PFOS, in a dose-dependent fashion, corresponding to the body burden.
- A small but persistent growth deficit was noted in the surviving pups, that was accompanied by a slight delay of development.
- Hypothyroxinemia was observed in the PFOS-exposed neonates.
- Liver hypertrophy was seen in the developing mice.

## Putative Mechanisms of PFOS Toxicity

- Interference of cholesterol and lipid     synthesis/transport
- Impedance of cell-cell communication through gap junction
- Alterations of mitochondrial bioenergetics
- Hepatotoxicity:  Peroxisome proliferation
- Thyroid hormone imbalance

## Critical Periods of Pup Survival

***Ho*****: PFOS Developmental Toxicity = Immaturity of **
**Pulmonary System**

## Perinatal Lung Histology

## Newborn Rats

**Newborn Rats**

- Control

- 5 mg/kg PFOS

- 10 mg/kg PFOS

- Pre-Perfused

- Post-Perfused

## Summary

- The mechanisms of developmental toxicity for PFOS are largely undefined, but are currently under active investigation.
- Our preliminary findings suggest that PFOS may compromise the structures and/or functions of the developing lung and liver, potentially leading to neonatal morbidity and mortality.

## On-going Efforts

- National monitoring program by CDC
- Long range research plans at NHEERL/ORD
- Health:  Pharmacokinetic models to relate body burden to 		reproductive and developmental toxicity
- 		           Elucidation of mechanisms responsible for PFOS 		developmental toxicity
- 		           Use of computational toxicology approach to 		explore the mechanisms of toxicity for the 			perfluorinated organic chemicals as a class
- Ecology:  Evaluation of toxicity using small fish and 			amphibian models

## Collaborators

- John Rogers
- Neil Chernoff
- Julie Thibodeaux
- Roger Hanson
- Brian Grey
- Brenda Barbee
- Rayetta Grasty
- Monica Logan

***OPPT, EPA***
- Jennifer Seed

***3M Company***
-   John Butenhoff
-   Lisa Stevenson
-   David Ehresman

***Michigan State Univ.***
-   John Giesy
-   Wendy Hu

**Collaborators**

***NIEHS***
-   Abraham Nyska

- Mark Stanton
- Judy Richards
- Douglas Wolf
- Hugh Barton
- Leona Clark

***NHEERL, ORD, EPA***