Fluorinated surfactants

The text on this page is taken from an equivalent page of the IEHIAS-project.

• A very diverse group, which all share an extreme persistence towards degradation.
• Major groups are perfluoroalkylsulfonic acids (e.g. PFOS), perfluorinated carboxylic acids (e.g. PFOA) and fluorotelomers.

Fluorinated surfactants as biomarkers

Sample collection and storage

Matrix:

• Perfluorinated alkyl substances (PFAS) are often associated with plasma albumin binding, which makes blood a suitable matrix.
• Few studies have shown significant concentrations of PFAS in human milk
• Cord blood may be a good indicator matrix as well.

Kinetics:

• The major exposure pathway of PFAS in by food
• Also exposure through inhalation of particle-bound PFAS has been observed
• PFAS are generally very inert and not likely to degrade
• Serum elimination half-life in occupationally exposed workers is estimated to be 8.7 years.

Sampling conditions:

• Blood samples can be taken using standard procedures, and are stored frozen at -20°C.
• Fluorotelomers are more volatile and need special attention.

Sample measurement

Analytical aspects:

• Because of the ubiquitous nature of PFAS, avoiding contamination of the samples is a major challenge.
• Analysis is usually performed using GC/MS or LC/MS techniques
• Detection limits depend on which matrix and compound is analysed

Performance characteristics:

• A first worldwide interlaboratory study highlighted that there are large differences in analytical performance
• Variations are mainly due to extraction and clean-up procedures.

Validation:

No particular guidelines for PFAS analysis in human tissues are available

Confounding factors:

Only gender has been illustrated to be a confounder, with higher serum concentrations of PFOS in males.

Data interpretation

Concentrations reported in literature:

	PFOS Female	PFOS Male	PFHxS Female	PFHxS Male	PFOA Female	PFOA Male	PFOSA Female	PFOSA Male
Maximum (ng/ml)	81	72	3,3	3,4	30,9	38,1	5,8	5,8
Minimum (ng/ml)	2,5	1,3	0,2	0,2	2,4	3,5	0,7	1

Dose-response/effect relationships:

• Most toxicological data is available for rodents,
• Very little epidemiological data for humans is available
• The NOAEL for males and females was considered to be around 0,03 mg/kg/day and 0,15 mg/kg/day respectively.

Time trend, geographical variation, susceptibel groups:

• Substantial increases of PFAS concentrations in the environment have been reported over the last decades.
• With the voluntary production stop of PFOS, concentrations are expected to decrease in the future.