Alcohols, C12-15-branched and linear

Monitoring data

Administrative data

Endpoint:

monitoring data

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Quantifying the anthropogenic fraction of fatty alcohols in a terrestrial environment.

Author:

Mudge, S. M, Deleo, P.C., Dyer, S.D.

Year:

2012

Bibliographic source:

Environmental Toxicology and Chemistry, Vol. 31, No. 6, pp. 1209–1222

Reference 2

Reference Type:

publication

Title:

Fatty alcohols – a review of their natural synthesis and environmental distribution. Report to ERASM (European Risk Assessment and Management) and the SDA (Soap and Detergent Association).

Author:

Mudge, S. M.

Year:

2005

Bibliographic source:

available online at http: //www. bangor. ac. uk/~oss034/Fatty_Alcohol_Natural_and_Anthropogneic_Sources.doc

Reference 3

Reference Type:

publication

Title:

Fatty Alcohols — Anthropogenic and Natural Occurrence in the Environment.

Author:

Mudge, S. M., Belanger, S. E., Nielsen, A. M.

Year:

2008

Bibliographic source:

Royal Society of Chemistry, London, UK. ISBN 978-0-85404-152-7.

Results and discussion

Any other information on results incl. tables

Introduction

Fatty alcohols are widely produced by bacteria, plants and animals for a variety of purposes. Land plants and insects may use fatty alcohols in the form of waxes for the prevention of desiccation, protection from bacterial attack and UV screening (Mudge et al., 2008). Terrestrial runoff may deliver long chain plant and insect waxes both associated with the parent biological material or after partial degradation in soils. Fatty alcohols are also used in detergent and cosmetic formulations, which may be sourced from either petroleum or biological materials (e.g. palm oils) and are typically disposed of down-the-drain. For example, detergent formulations include fatty alcohols either as underivatised components of alcohol ethoxylates (AE) or alcohol ethoxysulphates (AES). It is logical to assume that the multiple anthropogenic sources of fatty alcohols which pass through a WWTP would make a contribution to the local fatty alcohol loading in the environment.

 

However, an analytical tool, two dimensional stable isotope analysis (¹³C and²H) is suitable for characterizing and discriminating the different sources of fatty alcohols that may exist in a WWTP and in the receiving waters from that WWTP. After saponification, alcohols are extracted from the various samples, derivatised with a trimethylsilylating agent, and separated and analysed by gas-chromatography - mass spectrometry to identify and quantify the fatty alcohols. The samples were then analysed by compound specific isotope ratio mass spectrometry to generate a set of stable isotope pairs (δ¹³C and δ²H) for all samples. By plotting the stable isotope data for the various samples on a 2D plot (see below) it is possible to distinguish the source of the various alcohols in these samples (e.g. detergents from oleochemical sources, petroleum based detergents, terrestrial production, aquatic production and WWTP effluents).

 

European Study

A study was conducted at Treborth, North Wales (Mudge et al., 2010). Samples were collected from soils, plants, WWTP influent, effluent and sludge samples, marine sediments and detergents used in the catchment area. Stable isotope data were generated using the methods above. The isotope ratio data show that soils and terrestrially derived compounds do not have a significant contribution and that the major sources of fatty alcohols are derived from faecal matter (~75%) and petroleum based detergents (~25%). The effluent samples had short chain fatty alcohols only and the stable isotopes were different t other potential sources and indicative of bacterial synthesis during WWTP treatment. The sludge produced from the WWTP had relatively high concentrations of fatty alcohols as would be expected from their water solubility. The stable isotope signatures were consistent with a mixture of faecal and detergent sources. The marine sediment samples had short chain fatty alcohols that are typical of marine production and with stable isotope values that indicate exclusive marine production for the C14 alcohol with potentially mixed terrestrial for the C16 and C18 compounds. The fatty alcohols in the marine environments are therefore not derived from the WWTP effluent, which in turn are not directly derived from the fatty alcohols in the influent.

The estimated PECs based on EUSES modelling data (see Annex II) suggest that the amount of fatty alcohols added to the environment by anthropogenic use of the registered substances in EU is not significantly more than that to which the environment is typically adapted from natural sources.

 

North American Studies

To confirm the results observed in the European study, additional research into the source of alcohols observed in the environment was conducted in the United States. For the US studies, freshwater environments were selected as opposed to the marine environment examined in the Wales study. In addition, the impact of different waste water treatment technologies and ecological regions were also examined.

 

The initial study was conducted in Luray, Virginia (Mudge et al., 2012). Luray is in the Ecological Region 8.0 (sub-region 8.3, south eastern USA plains) and uses an oxidation ditch followed by UV irradiation for treatment of the waste water. Samples of river sediment, road dust and soil were collected above the waste water discharge, at the discharge and below the discharge. Waste water samples were also collected. The samples were processed and analyzed in the same manner as the Wales study. In addition to the environmental samples, a market survey of alcohol containing detergents and consumer products was conducted and samples of these products were analyzed.

 

The results from the Luray study were consistent with those obtained from the Wales study. The waste water influent was dominated by short chain alcohols (< C20) with the largest peak being C18 followed by C16, C14 and C12. However, the main alcohol in the effluent was phytol. Algae in the receiving stream were the likely origin of the phytol. The short chain alcohols in the effluent showed a reverse trend from the influent with the largest peak being C12 followed by C14 and C16. Based on the stable isotope data it was postulated bacterial synthesis was responsible for the formation of these alcohols.

 

Long chain alcohols (> C22) were dominant in the agricultural soil and road dust samples. The stable isotope data indicated these alcohols originated from terrestrial plants. An isolated peak of C16 in the agricultural soil was likely due to bacterial synthesis. Shorter chain alcohols (C14 to C18) were observed in river sediment samples at higher concentrations than in soil, however, long chain alcohols (> C22) still dominated the profile. While the sludge from the Luray WWTP was used as a soil amendment on a farm in the area, there was no evidence the alcohols contained in the sludge (total concentration - 900 µg/g) were transferred to the river.

 

To further define the impact of waste water treatment technologies and ecosystem regions on the source of alcohols occurring in the environment, an additional study was conducted in the United States (Mudge, 2012). Three different eco-regions and six different treatment technologies were examined. The eco-regions were the Marine West Coast Forest (Region 7), Eastern Temperate Forest (Region 8, including sub-regions 8.1, 8.2 and 8.4) and the Great Plains (Region 9). The waste water treatment processes were Oxidation Ditch, Activated Sludge, Percolating or Trickling Bed Filters (TBF), Lagoons, Rotating Biological Contactor (RBC) and Sequencing Batch Reactor (SBR).

 

Samples of the influent, effluent and sediments were collected from a total of 24 WWTP and analyzed as in the two previous studies. All of the technologies were effective at removing fatty alcohols from the influent with 98% removal. As with the previous studies, the stable isotope signature of the alcohols in the effluent was related to bacterial synthesis. Also as seen previously, the fatty alcohols observe in the sediments of the receiving waters were predominately from terrestrial plant matter. In addition, peaks of fatty alcohols from algal and bacterial synthesis sources were observed.

Applicant's summary and conclusion

Conclusions:

Using stable isotope signatures of fatty alcohols in a wide variety of household products and in environmental matrices sampled from river catchments in the United States and United Kingdom, (Mudge et al., 2012) estimated that 1% or less of fatty alcohols in rivers are from WWTP effluents, 15% is from in situ (algae, bacteria) production, and 84% is of terrestrial origin. Further, the fatty alcohols discharged from the WWTP are not the original fatty alcohols found in the influent. While the compounds might have the same chain lengths, they have different stable isotopic signatures (Mudge, 2012).

In conclusion, the environmental impact of these studies is that it has confirmed that the fatty alcohols entering a sewage treatment plant (as influent) are partly derived from detergents, but these are not the same alcohols as those in the effluent which arise from in-situ bacterial synthesis. In turn, the fatty alcohols found in the sediments near the outfall of the WWTP are derived from natural synthesis and are not the same alcohols as those in the effluent.

Executive summary:

The use of alkyl chainlength and isotope signatures of carbon and hydrogen have been used to distinguish the sources of fatty alcohols from detergents compared to environmental media such as wastewater and receiving water sediments. Recent studies by Mudge (2012) and Mudge et al. (2008, 2010 and 2012) have clearly shown that fatty alcohols rapidly biodegrade in wastewater treatment facilities, the majority associated with fecal and detergent sources, respectively. However, in receiving water sediments (freshwater and marine), evidence is conclusive that the signature corresponds to in-situ (algae, bacteria) production or terrestrial sources (runoff of faeces- and/or plant-based alcohols). Hence, fatty alcohols found in freshwater and marine environments are not sourced from detergents but from natural in-situ synthesis or terrestrial runoff sources.