Undecafluorhexansure

Perfluorohexanoic acid was not detected (detection limit 0.6 ng/mL) in the serum of 31 Boston, MA office workers in samples collected winter of 2009(1). The concentration of perfluorohexanoic acid in the serum of two of 20 Atlanta, GA residents was 0.7 and 6.7 ng/mL, samples were collected July 2003(2). Perfluorohexanoic acid was not detected in the serum, urine or stool of residence (males ages 52, 23, 21, 17, 15; females ages 48, 18) living in a home with a history of carpet Scotchgard application; samples were collected Nov 2008(3). Perfluorohexanoic acid was not detected (detection limit 0.3 ng/mL) in 40 pooled serum samples collected from 3802 Australian residents collected Nov 2002 to April 2003(4). Perfluorohexanoic acid was detected in blood serum samples collected July 1 through Sept 4, 2008 at 0.4-17 ug/L; samples were collected from 105 anglers (99 men, 6 women) that consumed fish from Lake Mohne, Germany(5). Perfluorohexanoic acid was not detected (detection limit 0.050 ng/mL) in 24 pooled serum samples from men, age 40 to 50 years, representing 1977 to 2006(6). Perfluorohexanoic acid was not detected (detection limit 1.0 ug/L) in blood plasma of men, women and children from German population in samples collected Sept to Nov 2006(7). Perfluorohexanoic acid was detected at <0.003-1.32 ng/mL in 420 human blood samples collected from volunteer residents from Halle and Munster, Germany; samples were collected 1982 to 2009(8). Perfluorohexanoic acid was detected in five of 66 human blood samples collected from 11 counties in Sweden during the period of 1997 to 2000, concentrations were <0.1-1.6 ng/mL(9). Human blood samples from volunteer donors from five Chinese cities (Shenyang, Beijing, Gulyang, Jintan, Nanjing) collected in 2004 had perfluorohexanoic acid concentrations of <0.01-0.18 ng/mL(10).

The concentration of perfluorohexanoic acid in 141 adult (age 20-55) human blood samples collected in 2008 from four cities located around Bohai Sea, China were as follows(1):[Table#8305]

The concentration of perfluorohexanoic acid in adult (age 19-62) human blood samples (15 samples from each category) taken from citizens of Gdansk, Poland and nearby villages was as follows. Blood donations were collected July 2003(1).[Table#8306]

... Perfluorohexanoic acid (PFHxA) and PFOA were used as model perfluorinated carboxylic acids (PFCAs) to characterize the major site of PFCA interaction in human sera. Using novel heteronuclear saturation transfer difference nuclear magnetic resonance spectroscopy experiments, human serum albumin (HSA) was identified as the major site of interaction for both PFHxA and PFOA in human sera. Heteronuclear single quantum coherence nuclear magnetic resonance experiments were then performed to interrogate site-specific interactions of PFHxA and PFOA with isolated HSA. Perfluorohexanoic acid was found to bind specifically to Sudlow's drug-binding site II, whereas PFOA interacted preferentially with Sudlow's drug-binding site I at the lower concentration, with additional interactions developing at the higher concentration. These experiments highlight the utility of nuclear magnetic resonance spectrometry as a tool to observe the in situ interactions of chemical contaminants with biological systems. Both PFCAs displaced the endogenous HSA ligand oleic acid at concentrations lower than observed for the drugs ibuprofen and phenylbutazone, which are established HSA ligands. Interactions between PFCAs and HSA may affect the pharmacokinetics and distribution of fatty acids and certain drugs in the human body and warrant further investigation.

EC50; Species: Skeletonema marinoi (Diatom) Exponential Growth Phase BA-98; Conditions: saltwater, static, 20 °C, pH 7.6-7.8; Concentration: 4.72 mM for 72 hr; Effect: decreased population growth rate /formulation/

EC50; Species: Geitlerinema amphibium (Blue-green Algae) Exponential Growth Phase BA-13; Conditions: saltwater, static, 20 °C, pH 7.6-7.8; Concentration: 3.18 mM for 72 hr; Effect: decreased population growth rate /formulation/

EC50; Species: Chlorella vulgaris (Green Algae) Exponential Growth Phase BA-02; Conditions: saltwater, static, 20 °C, pH 7.6-7.8; Concentration: 12.84 mM for 72 hr; Effect: decreased population growth rate /formulation/

TERRESTRIAL FATE: Based on a classification scheme(1), log Koc values of 1.63-2.35(2), indicate that perfluorohexanoic acid is expected to have very high to moderate mobility in soil(SRC). The pKa of perfluorohexanoic acid is -0.16(3), indicating that this compound will exist entirely in anion form in the environment and, therefore, volatilization from moist soil surfaces is not expected to be an important fate process(SRC). Perfluorohexanoic acid is expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.0 mm Hg at 25 °C(SRC), determined from a fragment constant method(4). Biodegradation data in soil were not available(SRC, 2016).

AQUATIC FATE: Based on a classification scheme(1), log Koc values of 1.63-2.35(2), indicate that perfluorohexanoic acid is expected to adsorb to suspended solids and sediment(SRC). A pKa of -0.16(3) indicates perfluorohexanoic acid will exist entirely in the anion form at pH values of 5 to 9 and, therefore, volatilization from water surfaces is not expected to be an important fate process(SRC). Perfluorohexanoic acid is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(4). According to a classification scheme(5), a reported BCF of 0.59 in rainbow trout(6), suggests bioconcentration in aquatic organisms is low(SRC). Biodegradation data in water were not available(SRC, 2016).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), perfluorohexanoic acid, which has an estimated vapor pressure of 2.0 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase perfluorohexanoic acid is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 31 days(SRC), calculated from its rate constant of 5.2X10-13 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(2). Perfluorohexanoic acid does not contain chromophores that absorb at wavelengths >290 nm(3) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

Perfluorohexanoic acid was detected in four tap water samples from Amsterdam, The Netherlands at 2.2-2.4 ng/L; cola mixed with this tap water had perfluorohexanoic acid concentrations of 0.16-2.0 ng/L(1). In Nov 2009, food products of 15 food categories were randomly purchased in several Dutch retail stores, perfluorohexanoic acid was detected as follows (pg/g product); fatty fish (<5), lean fish (<3), crustaceans (<4), butter (20), cheese (<9), milk (<6), eggs (<54), pork (<11), beef (<5), chicken/poultry (<7), bakery products (<9), vegetables/fruit (<4), flour (11), vegetable oil (<3), and industrial oil (<5)(2). Seven types of seafood were purchased from local markets in Zhoushan and Guangzhou, China in 2004, perfluorohexanoic acid was only detected in swimming crab from Guangzhou at 0.29 ng/g wet weight(3).

Perfluorohexanoic acid was not detected (detection limit 0.15 ng/g) in 12 raw and 49 retail milk samples collected at locations across the US(1). In Nov 2009, milk samples randomly purchased in several Dutch retail stores did not contain perfluorohexanoic acid (detection limit 6 pg/g)(2). Perfluorohexanoic acid was detected in one of two human milk samples at 0.82 ng/mL, collection data were not provided(3).

IDENTIFICATION AND USE: Perfluorohexanoic acid (PFHxA) is a colorless liquid. It is a long-chain perfluoroalkanecarboxylic acid, a group of surfactants which are used as wetting, dispersing, emulsifying, and foaming agents. PFHxA is also used in protective coatings for fabrics and carpet, paper coatings, and insecticide formulations. HUMAN EXPOSURE AND TOXICITY: PFHxA exposure may be associated with Gilbert Syndrome (a mild genetic liver disorder in which the body cannot properly process bilirubin). Studies indicate that perfluorinated compounds such as PFHxA are not acutely toxic at the cellular level. In human hepatoma Hep G2 cells, there was no indication that PFHxA induces cytotoxicity via an apoptotic mechanism. ANIMAL STUDIES: PFHxA appears to have a very low acute biological activity in animals. Researchers carried out a 90-day toxicological evaluation of PFHxA in rats following oral gavage. Adverse changes observed included hepatic peroxisomal beta-oxidation and hepatic and thyroid changes. A similar experiment resulted in lower body weight gains in males, lower red blood cell parameters, higher reticulocyte counts, lower globulin, lower total protein and higher albumin/globulin ratio, and lower cholesterol and calcium. PFHxA showed no major effects on messenger RNA (mRNA) levels of thyroid hormone (TH)-responsive genes in chicken embryonic neuronal cells. There is no evidence that PFHxA is tumorigenic in male or female rats. ECOTOXICITY STUDIES: The effects of acute toxicity, 3-day population growth, and morphological effects of perfluorinated carboxylic acids (PFCAs) with carbon chain lengths of 2-6 on the freshwater rotifer Brachionus calyciflorus were investigated. The results indicated that the 24-hr median lethal concentration (LC50) value of PFHxA towards B. calyciflorus was 140 mg/L. The acute effects of PFCAs decreased with the increase of carbon chain length. Flow cytometric measurements were used to investigate the toxic effect of PFHxA on some membrane systems of the freshwater alga species Scenedesmus obliquus. PFHxA did not inhibit algal growth within the test concentration ranges.

/AQUATIC SPECIES/ The effects of acute toxicity, 3-day population growth and morphological effects of perfluorinated carboxylic acids (PFCAs) with carbon chain lengths of 2-6 on the freshwater rotifer Brachionus calyciflorus were investigated. The results indicated that the 24-hr median lethal concentration (LC50) values of trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), perfluorobutanoic acid (PFBA), perfluopentanoic acid (PFPeA), and perfluorohexanoic acid (PFHxA) towards B. calyciflorus were 70, 80, 110, 130 and 140 mg/L, respectively. The acute effects of PFCAs decreased with the increase of carbon chain length. The parameters used to determine 3-day population growth on these compounds were the rate of population increase (r) and mictic ratio. With the increase of fluorinated carbon-chain length, the r values of TFA, PFPrA, PFBA, PFPeA and PFHxA decreased by 0.99%, 16.8%, 16.5%, 22.4% and 32.0%, respectively. Mictic ratios ranged from 0.707 to 0.953 for PFCAs with carbon chain lengths of 2-6. In addition, the mictic ratio, body size and egg size exposed to some PFCAs were higher than those of the controls. These results offer a useful method for the ecological risk assessment of these short chain PFCAs.

/AQUATIC SPECIES/ Flow cytometric measurements were used to investigate the toxic effect of perfluorobutanoic sulfonate (PFBS), perfluorooctane sulfonate (PFOS), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorododecanoic acid (PFDoA), and perfluorotetradecanoic acid (PFTeA) on some membrane systems of the freshwater alga species Scenedesmus obliquus. Among the test compounds, PFOS, PFDoA, and PFTeA inhibited algal growth rate in a concentration-dependent manner while PFBS, PFHxA, and PFOA did not inhibit algal growth within the test concentration ranges. An enhancement of the mitochondrial membrane potential (MMP) and cell membrane permeability in S. obliquus was observed caused by exposure to PFOS, PFOA, PFDoA, and PFTeA. Both carbon chain length and acid group influenced the toxicity of PFAAs, where the toxicity increased with increasing carbon chain length for the compounds belonging to the same class. The observed effective concentrations lie in the micromole range and the test compounds disrupted membrane properties at concentrations below those associated with algal growth inhibition. Flow cytometry is proved to be a useful technique for toxicity testing with microalgae and provide additional information regarding the mode of action of PFAAs to algal species.

Grass samples were collected from fields treated with bio-solids in 2009 near Decatur, AL; perfluorohexanoic acid concentrations were 22.9, 30.2-182.2 and 26.3 ng/g dry weight in Kentucky blue grass, tall fescue and Bermuda grass, respectively(1).

Perfluorohexanoic acid was detected in all the marine mammal samples (grey seal, minke whale, pilot whale) taken from Sweden, Denmark, Iceland and the Faeroe Islands(1). Perfluorohexanoic acid was not detected (detection limit 0.1 ng/g wet weight) in northern fulmar (Fulmarus glacialis) and thick-billed murre (Uria lomvia) eggs sampled 1971-2007 and 2010-2011 from Prince Leopold Island, Nunavut, Canada; in 2009 perfluorohexanoic acid was detected in fulmar eggs at 0.11 ng/g and in 2008 and 2009 was detected in murre eggs at 0.02 and 0.08 ng/g, respectively; black guillemot (Cepphus grylle), black-legged kittiwake (Rissa tridactyla) and glaucous gull (Larus hyperboreus) eggs sampled in 2008 did not contain perfluorohexanoic acid(2). Perfluorohexanoic acid was not detected (detection limit 50 pg/mL) in blood samples from 16 eider duck (Somateria mollisima), collected from the Gulf of Gdansk in Feb 2003(3). Perfluorohexanoic acid was not detected (detection limit ng/g) in the muscle (1.0), kidney (0.51), adult liver (1.9), chick liver (1.3) or egg (0.75) of common guillemot (Uria aalge) samples from Stora Karlso Island in the Baltic Sea collected in 1989(4). Perfluorohexanoic acid was detected at 590, 160 and 80 pg/mL in blood plasma from three Japanese black beef cattle at 9 months of age, these concentrations decreased to 100, 80 and 50 pg/mL at 27 months of age(5). Perfluorohexanoic acid was detected in the blood of six of 67 loggerhead sea turtles (Caretta caretta) at <100-124 pg/mL and not detected (detection limit 100 pg/mL) in six Kemp's ridley sea turtles (Lepidochelys kempii); samples were collected June-July 2003 along the coast of South Carolina, Georgia and Florida(6). Perfluorohexanoic acid was not detected (detection limit 0.01 ng/g wet weight) in eggs of little egret (Egretta garzetta) and night heron (Nycticorax nycticorax) from Quanzhou, Xiamen, and Hong Kong, South China, but was detected at <0.01-0.071 in eggs from great egret (Ardea alba) collected from Hong Kong; respective sampling dates were March-May 2004, March-May 2004 and March-May 2006(7). Perfluorohexanoic acid was detected in one of 40 fox (Vulpes vulpes) livers tested at 1.4 ug/kg wet weight, but not detected in chamois (Rupicapra rupicapra) livers sampled; fox were collected from Germany and chamois from Austria(8).