Higher alcohols YRTPH 2102 (PDF)

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Regulatory Toxicology and Pharmacology 50 (2008) 313–321
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Defining maximum levels of higher alcohols in alcoholic
beverages and surrogate alcohol products
Dirk W. Lachenmeier a,*, Simone Haupt a, Katja Schulz b
a

Chemisches und Veterina¨runtersuchungsamt (CVUA) Karlsruhe, Weißenburger Strasse 3, D-76187 Karlsruhe, Germany
b
Institut fu¨r Rechtsmedizin, Technische Universita¨t Dresden, Fetscherstrasse 74, D-01307 Dresden, Germany
Received 13 September 2007
Available online 16 January 2008

Abstract
Higher alcohols occur naturally in alcoholic beverages as by-products of alcoholic fermentation. Recently, concerns have been raised
about the levels of higher alcohols in surrogate alcohol (i.e., illicit or home-produced alcoholic beverages) that might lead to an increased
incidence of liver diseases in regions where there is a high consumption of such beverages. In contrast, higher alcohols are generally
regarded as important flavour compounds, so that European legislation even demands minimum contents in certain spirits. In the current
study we review the scientific literature on the toxicity of higher alcohols and estimate tolerable concentrations in alcoholic beverages.
On the assumption that an adult consumes 4  25 ml of a drink containing 40% vol alcohol, the maximum tolerable concentrations of
1-propanol, 1-butanol, 2-butanol, isobutanol, isoamyl alcohol and 1-hexanol in such a drink would range between 228 and 3325 g/hl of
pure alcohol. A reasonable preliminary guideline level would be 1000 g/hl of pure alcohol for the sum of all higher alcohols. This level is
higher than the concentrations usually found in both legal alcoholic beverages and surrogate alcohols, so that we conclude that scientific
data are lacking so far to consider higher alcohols as a likely cause for the adverse effects of surrogate alcohol. The limitations of our
study include the inadequate toxicological data base leading to uncertainties during the extrapolation of toxicological data between the
different alcohols, as well as unknown interactions between the different higher alcohols and ethanol.
Ó 2008 Elsevier Inc. All rights reserved.
Keywords: Higher alcohols; Methanol; Ethanol; Propanol; Butanol; Alcoholic beverages; Fusel oil; Surrogate alcohol

1. Introduction
Alcohols with more than two carbon atoms are commonly called higher or fusel alcohols. In the 19th century,
the predominant opinion was that higher alcohols were a
contamination of alcoholic beverages derived as metabolites
from bacterial spoilage (Huckenbeck and Bonte, 2003).
However, since Ehrlich’s work at the beginning of the 20th
century it has been known that higher alcohols are formed
by yeast metabolism from amino acids and therefore are normal constituents naturally found in all alcoholic beverages
derived from alcohol of agricultural origin (Ehrlich, 1906,
1907, 1913). In contrast, methanol is formed from pectines
and not from yeast metabolism (von Fellenberg, 1914). An
*

Corresponding author. Fax: +49 721 926 5539.
E-mail address: Lachenmeier@web.de (D.W. Lachenmeier).

0273-2300/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved.
doi:10.1016/j.yrtph.2007.12.008

excellent evaluation of the tolerable concentration of methanol in alcoholic beverages is available in the literature (Paine
and Dayan, 2001). Law already limits the methanol content
in alcoholic beverages (European Council, 1989). Therefore,
methanol will not be discussed in this article, which instead
concentrates on higher alcohols for which there is no similar
information.
The major higher alcohols found in alcoholic beverages
are 1-propanol (n-propyl alcohol), 1-butanol (n-butyl alcohol), 2-butanol (sec. butyl alcohol), iso-butanol (2-methyl1-propanol) and isoamyl alcohol (3-methyl-1-butanol). An
interesting discrepancy should be noted about the evaluation of higher alcohols in alcoholic beverages:
On the one hand, higher alcohols are treated as important flavour compounds. For example, they commonly
account for about 50% of the aromatic constituents of
wine, excluding ethanol (Jackson, 2000). In food legisla-

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tion, the content of higher alcohols in alcoholic beverages
is generally not seen as toxicologically relevancant. For
example, the Joint FAO/WHO Expert Committee on Food
Additives included higher alcohols (1-propanol, 1-butanol,
isobutanol) in the functional class ‘flavouring agent’ and
commented that there was no safety concern at current levels of intake (JECFA, 1997). For certain groups of spirits,
the European Union even demands a minimum volatile
substance content (i.e., the quantity of volatile substances,
mainly higher alcohols, other than ethanol and methanol).
For example, brandy, fruit spirits or rum must have at least
a content of volatile substances of 125, 200 or 225 g/hl of
pure alcohol, respectively (European Council, 1989).
On the other hand, in previous studies of surrogate alcohol a number of authors attributed the possible higher toxicity of this group of illegal or home-produced alcohol to its
content of higher alcohols (Lachenmeier et al., 2007). For
example, compared to consumers of mainly licit alcohol,
consumers of home made ‘country liquor’ in India have been
reported to have higher rates of alcoholic liver disease
(Narawane et al., 1998), and an animal study on rats suggests
that ‘‘toddy” (an Indian country liquor) had increased toxicity compared to the same dose of pure ethanol (Lal et al.,
2001). McKee et al. (2005) concluded from a study of Russian samogons (the Russian name for illegally home-distilled
alcoholic beverages) that they contain aliphatic alcohol
congeners at ‘‘toxicologically relevant levels”. Lang et al.
(2006) went so far as to conclude that illegal products in
Estonia contain ‘‘toxic long chain alcohols”. Regrettably,
the latter studies did not state how they derived this conclusion or what they consider a ‘‘relevant” or ‘‘toxic” level.
In summary, higher alcohols have been treated as ‘‘generally recognized as safe” or as ‘‘toxicologically relevant”.
Accordingly, our study tries to answer the question of the
maximum tolerable level of this important substance class
in alcoholic beverages.
2. Methods
In order to derive such maximum levels of higher alcohols in alcoholic
beverages, data on the toxicity of higher alcohols were obtained by a computer-assisted literature search in the following databases: PubMed, Toxnet
and ChemIDplus (U.S. National Library of Medicine, Bethesda, MD), Web
of Science (Thomson Scientific, Philadelphia, PA), IPCS/INCHEM (International Programme on Chemical Safety/Chemical Safety Information
from Intergovernmental Organizations, WHO, Geneva, Switzerland), Food
Science and Technology Abstracts (International Food Information Service, Shinfield, UK), and Scopus (Elsevier B.V., Amsterdam, Netherlands).
The references, including abstracts, were imported into Reference Manager
V.11 (Thomson ISI Research Soft, Carlsbad, CA) and the relevant articles
were manually identified and purchased in full text. The reference lists of
all articles were checked for relevant studies not included in the databases.

3. Results and discussion
3.1. Acute toxicity of higher alcohols
As early as 1869, Richardson pointed out that the
potency of aliphatic alcohols increases with their molecular

weight (Richardson, 1869). This has come to be known as
Richardson’s law. The law was verified by numerous studies (e.g., Lehman and Newman, 1937; MacGregor et al.,
1964; McLaughlin et al., 1964; Munch and Schwartze,
1925; Weese, 1928; Welch and Slocum, 1943). In 1907,
Fu¨hner and Neubauer (1907) concluded the toxicity as
measured by narcotic and haemolytic activity of normal
monohydric alcohols from ethyl to octyl to be in the relation of 1:31:32:33:34:35. This received confirmation in the
work of Kamm (1921), who found that it held approximately true when the toxicity of these alcohols to paramecia was determined.
A third generalization was made by Macht (1920) when
it was found that the iso-alcohols were less toxic to cats
than the corresponding normal isomer. Beer and Quastel
(1958) and Wallgren (1960) confirmed that toxicity and
narcotic effects of aliphatic alcohols seem to increase with
increasing length of the carbon chain and decrease from
primary to secondary and from secondary to tertiary
alcohols.
In the context of Richardson’s law one restriction must
be mentioned. As early as 1920, Macht (1920) had pointed
out a possible error in interpreting the available data collected in studies on acute toxicity, and called attention to
the possibility of more toxic metabolites. Murphree et al.
(1967) pointed out some obvious problems: Richardson’s
law applies only to primary toxic effects. For example,
methanol is of course more toxic than ethanol because of
its metabolites, formaldehyde and formic acid. Skog
(1950) noted that for aldehydes, the toxicity decreased with
an increase of molecular weight, and this applied whether
the aldehyde was saturated or unsaturated. Richardson’s
law obviously does not apply to the aldehydes. Thus while
it is true that methanol is less toxic than ethanol acutely,
this does not take into account the optic nerve damage
caused by methanol, which appears only after a latent
period.
The acute toxicity of alcohols was summarized by the
International Programme on Chemical Safety (IPCS,
1987a, 1990, 1997), as well as the OECD SIDS programme
(OECD SIDS, 2004). Data about the acute oral toxicity of
alcohols and their metabolites in rats are summarized in
Table 1.
3.2. Chronic toxicity, liver toxicity and neurotoxic effects of
higher alcohols
Long-chain aliphatic alcohols contained in products not
intentionally produced for consumption (e.g., antifreeze)
but also in home-made products intended as beverage alcohol have been linked with a higher hepatotoxicity. However, the occurrence and severity of detrimental health
outcomes clearly depends on the concentration of these
substances. So far it is unclear if the relatively low content
of higher alcohols in combination with high concentrations
of ethanol have a consequence on the etiology of liver diseases. Gibel et al. (1969) reported severe hepatic damage

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315

Table 1
Oral LD50 data and relative toxicities of alcohols and their metabolites
Alcohol

LD50 (rat,
oral)[mg/kg]

Reference

Metabolite

LD50 (rat,
oral)[mg/kg]

Reference

Methanol
Ethanol
1-Propanol
1-Butanol
2-Butanol
Isobutanol

5628
7060
1870
790
2193
2460

Larionov and Broitman (1975)
Wiberg et al. (1970)
Smyth et al. (1954)
Purchase (1969)
ChemIDplus (2007a)
Smyth et al. (1954)

Formaldehyde (Methanal)
Acetaldehyde (Ethanal)
Propionaldehyde (Propanal)
Butyraldehyde (Butanal)
Methylethylketone (2-Butanone)
Isobutyraldehyde (2-Methylpropanal)

100
661
1410
2490
2737
960

Isoamyl alcohol

1300

Purchase (1969)

Isovaleraldehyde (3-Methyl-1-butanal)

5600

1-Hexanol

720

Purchase (1969)

Capronaldehyde (Hexanal)

4890

Til et al. (1988)
Sprince et al. (1974)
Smyth et al. (1951)
ChemIDplus (2007b)
Kimura et al. (1971)
Solotow and Swintuchowski
(1972)
Afanasjewa and Bitkina
(1987)
Smyth et al. (1954)

occurring in rats treated with high doses of corn fusel oil
containing aldehydes, esters, and a large number of higher
alcohols. Peneda et al. (1994) confirmed those results and
suggested that the hepatotoxicity of ethanol may be
enhanced by interaction with its congeners and acetaldehyde; they also suggested that alcoholic beverages are not
equivalent in their potential to cause liver damage.
In contrast, Siegers et al. (1974) administered four alcoholic congeners orally to guinea-pigs at doses up to 100fold higher than those which can be expected at the most
by human binge drinking and detected no hepatotoxic
activity. The experiments of Hillbom et al. (1974), feeding
rats with 1 M solutions of ethanol, n-propanol, or 2methyl-1-propanol over 4 months, also failed to produce
a hepatotoxic response.
Hepatotoxicity may be assessed by assaying liver cytosol-derived enzymes such as lactate dehydrogenase
(LDH), glutamate-pyruvate-transaminase (GPT) or glutamate dehydrogenase (GLDH). McKarns et al. (1997) evaluated the release of LDH by rat liver epithelial cells in vitro
after acute exposure to 11 short-chain alcohols and found a
correlation between the hydrophobicity of these alcohols
and their ability to alter plasma membrane integrity. Strubelt et al. (1999) studied 23 aliphatic alcohols in the isolated, perfused rat liver. The capacity of the straight
chain primary alcohols (methanol, ethanol, 1-propanol,
1-butanol and 1-pentanol) to release GPT, LDH and
GLDH into the perfusate was clearly correlated with their
carbon chain length. The secondary alcohols (2-propanol,
2-butanol, 2-pentanol, 3-pentanol) were less active in this
respect, whereas branching of the carbon chain (2methyl-1-butanol, 3-methyl-1-butanol) did not consistently
change alcohol toxicity. Alcohol-induced hepatotoxicity
was primarily due to membrane damage induced by the
direct solvent properties of the alcohols. Strubelt et al.
(1999) concluded that the consequences and relative contributions of alcohol metabolization to the overall hepatotoxicity of higher alcohols required further study.
The neurotoxicity of ethanol leading to regional brain
damage and cognitive dysfunction has been extensively
researched and recently reviewed (Harper, 2007). Similar
information is missing for the higher alcohols; however,

it was pointed out that the shared properties of all alcohols
suggest a unifying mechanism of neurotoxicity (Shoemaker, 1981). There appears to be evidence linking higher
alcohols with the hangover effects after consuming alcoholic beverages, as there were differences found between
beverages like vodka (without higher alcohols) and whisky
(Bonte and Volck, 1978; Murphree et al., 1967). However,
these differences might be as well attributed to other constituents like acetaldehyde or compounds from aging in
wood casks that are found abundantly in whiskey.
3.3. Metabolism and Pharmacodynamics of higher alcohols
All primary alcohols under investigation are metabolised to their corresponding aldehydes by the same main
enzymatic pathway: the alcohol dehydrogenase (ADH)
(Lutwak-Mann, 1938; Theorell, 1965; Theorell and Bonnichsen, 1951; von Wartburg et al., 1965; Winer, 1958).
The other enzymatic pathways known from ethanol metabolism, the katalase and the microsomal ethanol oxidizing
system (MEOS), similarly oxidize the alcohols to their aldehydes (Caballeria et al., 1986, 1989; DiPadova et al., 1987;
Frezza et al., 1990; Julkunen et al., 1985). The secondary
alcohol 2-butanol is also enzymatically metabolised by
ADH, but to the corresponding ketone (methylethylketone) (Aarstad et al., 1986; Dietz et al., 1981).
In the literature, there are differing views about the oxidizing rate of fusel alcohols in comparison to ethanol. The
oxidizing rate also depends on the isomerism of the alcohol: Grab (1961) and Hedlund and Kiessling (1969)
reported that primary alcohols are metabolised faster than
secondary alcohols, which in turn are faster than tertiary
alcohols.
The aliphatic alcohols may inhibit themselves in their
oxidation. Abshagen and Rietbrock (1970) confirmed that
the order of competitive inhibition depends on the affinity
of alcohol to ADH and the concentration at the enzyme.
The inhibition of oxidation increases with an increasing
carbon-chain length (von Wartburg et al., 1964). In the
case of higher alcohols, which were eliminated exponentially and hence independent from concentration, the competitive inhibition is shown by extension of half-value time.

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The consumption of higher alcohols mostly occurs in conjunction with alcoholic beverages. Therefore, ethanol is
available in great excess. Despite of the greater affinity of
higher alcohols to the enzyme, the inhibition of fusel alcohols by ethanol has been observed by Greenberg (1970)
and Bonte et al. (1981a). Drinking tests with human volunteers, with only congener substances (1-propanol, isobutanol and 3-methyl-1-butanol) and without ethanol, resulted
in no detectable concentrations of congeners in whole
blood samples. The same tests with ethanol at different
concentrations resulted in detectable concentrations of
1-propanol and isobutanol. With increasing ethanol
concentrations the congener concentrations also increased.
3-Methyl-1-butanol could not be detected under these test
conditions (Bonte, 1987). In alcoholic beverages the low
concentrated fusel alcohols seems to be not inhibited
among another in presence of the high concentrated ethanol (Bonte, 1987). The same effect of inhibition was
observed by oxidation of aldehydes among themselves at
the enzyme aldehyde dehydrogenase (ALDH) by Hedlund
and Kiessling (1969). There is a sparsity of literature on the
interactions between the higher alcohols themselves and
with ethanol. The pharmacodynamically interactions
between ethanol and other substances are regularly additive effects (Schmidt and Wehling, 2002). So far, there is
no evidence pointing to multiplicative effects in the toxicity
of the different alcohols.
Another metabolic pathway of higher alcohols is the
conjugation with activated glucuronic acid, a phase-IIreaction. Bonte et al. (1981b) reported that drinking tests
with human volunteers resulted in high concentrations of
glucuronides of isobutanol, 2-methyl-1-butanol and 3methyl-1-butanol in urine samples. The other higher alcohols were not conjugated appreciably. In blood samples
the same effects were observed by Bonte et al. (1983).
The individual glucuronidation rate seems to be different
(Sprung et al., 1983a,b). The conjugation of higher alcohols
with activated sulphuric acid was observed by Vestermark
and Bostro¨m (1959) to a minor extent. The carbonic
acids—second metabolites of alcohols—may be detected
as glucuronides in blood and urine samples (Ru¨dell et al.,
1983).
The relevant blood concentrations of higher alcohols
occurring after consumption of alcoholic beverages range
below 100 lg/ml for 2- and 3-methyl-1-butanol, between
100 and 2000 lg/l for 1-propanol, isobutanol, 2-butanol
and 1-butanol and above 50 mg/l for methanol in special
cases.
Wirth and Gloxhuber (1994) reported a fatal intoxication with 2-methyl-1-butanol. Further articles about fatalities after consumption of higher alcohols have not been
published to our knowledge. Reports of death following
consumption of illicit liquors are available, but can generally attributed to methanol or ethanol toxicity alone (Lachenmeier et al., 2007). In the post-mortem toxicological
evaluation of alcohol intoxications, as well as in epidemiological studies there is always a confounding of effects due

to the co-ingestion of ethanol with higher alcohols. Therefore, human data is completely lacking in the toxicity evaluation of higher alcohols, and we have to apply the
traditional NOAEL/ADI approach to interpolate from
animal data.

3.4. Estimation of tolerable concentrations of higher alcohols
in alcoholic beverages
Despite the numerous previously mentioned reports
about the acute toxicity of higher alcohols (i.e., LD50 values), we detected a general lack of data about no observed
adverse effect levels (NOAEL) in animal experiments, from
which acceptable daily intakes (ADI) or maximum limits in
foods could be derived.
For higher alcohols, we found NOAEL values only for
1-butanol and isoamyl alcohol. The subchronic toxicity
of 1-butanol was studied in rats and a NOAEL of
125 mg/kg/day was observed (OECD SIDS, 2004). The
no-effect level of isoamyl alcohol in rats was determined
to be 1000 mg/kg/day (Carpanini et al., 1973). In both
studies, no dose-related differences were observed on mortality between treatment or control rats. The 1-butanol
study reported ataxia and hypoactivity in both sexes of
the high dose group (500 mg/kg/day) during the final six
weeks of the dosing period. No treatment related signs
were observed in the 30 or 125 mg/kg/day treatment
groups. In the isoamyl acohol study, no effects associated
with treatment were found in results of haematological
examinations, serum analyses, urinary cell counts, renal
concentration tests or organ weights.
Due to the missing data, the NOAEL values of the other
alcohols can only be estimated. Because of the very similar
effects and metabolization of the alcohols, it appears to be
possible and permissible to interpolate the NOAEL values
using the relative acute toxicities for conversion. The
assumption made is that the NOAEL values are correlated
to the LD50 values. Previous reports have shown that such
an approach is possible (Layton et al., 1987; Kramer et al.,
1996). The results of our estimations are given in Table 2.
In the next step, the ADI values were calculated from
the NOAEL values (Table 3). The traditional safety factor
of JECFA was chosen (100), which assumes that the
human being is 10 times more sensitive than the test animal
and that the difference of sensitivity within the human population is in a 10-fold range (IPCS, 1987b).
For comparison, we also show data derived from human
toxicity studies about methanol in Table 3. The ingestion of
up to 20 mg methanol/kg by healthy or moderate folatedeficient humans should not result in formate accumulation above endogenous levels (IPCS, 1997). Paine and
Dayan (2001) came to a similar conclusion and found the
safe concentration of methanol to be 1950 mg for a 70-kg
person (28 mg/kg). For our evaluation we use the more
conservative level of 20 mg/kg as a tolerable concentration
of methanol. From this value, the concentrations for the

D.W. Lachenmeier et al. / Regulatory Toxicology and Pharmacology 50 (2008) 313–321
Table 2
NOAEL for alcohols estimated from 1-butanol and isoamyl alcohol using
the relative acute toxicities
Alcohol

NOAEL (mg/kg/day)
calculated from
1-butanol

NOAEL (mg/kg/day)
calculated from isoamyl
alcohol

Methanol
Ethanolb
1-Propanol
1-Butanol
2-Butanol
Isobutanol
Isoamyl alcohol
1-Hexanol

891
(1117)
296
125a
347
389
206
114

4329
(5431)
1438
608
1687
1892
1000a
554

317

Of course, these concentrations must be read as preliminary in light of several methodological limitations to
our study. As we have pointed out above, the toxicological
data base is inadequate so that the extrapolation between
the different alcohols is necessary. Furthermore, there is
no data available about interactions between the alcohols
(see Section 3.3).
3.5. Evaluation of higher alcohols in alcoholic beverages

a

Experimental data, other values were calculated in relation to the acute
toxic effects given in Table 1.
b
Due to its carcinogenicity (IARC, 2007), no NOAEL was established
for ethanol. The values are shown in brackets for comparative reasons
only.

other alcohols were extrapolated again by their relative
acute toxicities.
The human-derived value for methanol of 20 mg/kg is in
the same order of magnitude than the extrapolated ADI values of 8.9 (from 1-butanol) or 43 mg/kg (from isoamyl alcohol), which proves the validity of the estimation. Due to the
aforementioned fact that iso-alcohols may be of lower toxicity than the straight chain alcohols, the extrapolations from
1-butanol are more conservative and appear to provide
higher safety. The excellent agreement between the humanderived and extrapolated values for methanol also proves
that the safety factor is in the right order. Higher safety factors (e.g., 1000), that may be justifiable from a theoretical
standpoint due to the sub-chronicity of the NOAEL studies,
appear to be too conservative as they would inadequately
ignore the epidemiological evidence for methanol being the
most toxic of the alcohols with documented cases of poisonings and fatal intoxications (Lachenmeier et al., 2007).
In accordance with the definition of a tolerable concentration of methanol in alcoholic beverages by Paine and
Dayan (2001), an ingestion of 4  25 ml of spirit by a 70kg adult is used as reference for calculation of ‘‘safe” levels.
The maximum tolerable levels of higher alcohols in such a
spirit are given in Table 4.

The current European legislation provides only a maximum limit for the sum of higher alcohols in neutral alcohol
(European Council, 1989). The limit is 0.5 g/hl of pure
alcohol (g/hl p.a.), which is more than a factor of 100 lower
than the maximum tolerable concentration derived in our
study for any of the alcohols. Therefore, most spirits manufactured with neutral alcohol (e.g., vodka, most liqueurs,
gin, absinthe) pose no safety concern in regard to higher
alcohols.
For other groups of spirits, mainly products distilled
with retention of the organoleptic properties of their raw
materials (e.g., rum, brandy, grape marc, fruit spirits), minimum contents of higher alcohols are required by European law (see Table 4). However, the spirits usually
contain higher levels than those minimum requirements.
A histogram of 290 different spirit samples, including all
typical groups found on the European market, analyzed
between 2006 and 2007 according to the European reference method (European Commission, 2000) is shown in
Fig. 1. The mean content of higher alcohols is approximately 400 g/hl p.a., and the spirits usually do not contain
more than 1000 g/hl p.a. of higher alcohols. In this typical
range the maximum tolerable concentrations may be
exhausted but not yet exceeded.
Our evaluation therefore validates the previously mentioned JECFA statement that there is no safety concern
about higher alcohols at current levels of intake when used
as flavouring agent (JECFA, 1997).
In our sample collective, only 5 samples had abnormally
high concentrations of higher alcohols (1070, 1158, 1333,
1364, 1482, 2161, 2337 and 5901 g/hl p.a.), which may lead
to toxicological concerns as the acceptable daily intake
may be exceeded.

Table 3
ADI values for alcohols calculated from NOAEL with safety factor of 100
Alcohol

ADI (mg/kg/day) calculated from
NOAEL derived from 1-butanol

ADI (mg/kg/day) calculated from
NOAEL derived from isoamyl alcohol

ADI (mg/kg/day) calculated
from safe methanol intake

Overall evaluation
ADI (mg/kg/day)

Methanol
Ethanolb
1-Propanol
1-Butanol
2-Butanol
Isobutanol
Isoamyl alcohol
1-Hexanol

8.9
(11)
3.0
1.3a
3.5
3.9
2.1
1.1

43
(54)
14
6.1
17
19
10a
5.5

20a
(25)
7
3
8
9
5
3

20a
(11–54)
3.0–14
1.3a
3.5–17
3.9–19
10a
1.1–5.5

a
b

Value derived from experimental data.
Due to its carcinogenicity (IARC, 2007), no ADI was established for ethanol. The values are shown in brackets for comparative reasons only.

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Table 4
Maximum levels in spirits (assumption: 70 kg adult consuming 100 ml of spirit at 40% vol)
Alcohol

Maximum level (mg/l)

Methanol
Ethanolc
1-Propanol
1-Butanol
2-Butanol
Isobutanol
Isoamyl alcohol
1-Hexanol

14000
(7700–37800)
2100–9800
910
2450–11900
2730–13300
7000
770–3850

Maximum level (g/hl p.a.)

Current EU legislation (g/hl p.a.)
a

3500
–
525–2450
228
613–2975
683–3325
1750
193–963

50–1500
–
Sum of higher alcoholsb:
Neutral alcohol: <0.5;
Rum: >225;
Brandy: >125;
Marc: >140;
Fruit spirit: >200

Proposal of legislative limit (g/hl p.a.)
–
–
Sum of higher alcohols:
Distilled spirits <1000

a
The methanol limit depends on the type of beverages, e.g., neutral alcohol: 50 g/hl p.a., brandy: 200 g/hl p.a., grape marc spirit/Grappa: 1000 g/hl p.a.,
fruit spirits dependent on type of fruit: 1000–1500 g/hl p.a. (European Council, 1989).
b
The minimum requirement for distilled spirits (rum, brandy, marc, fruit spirit) includes other volatiles besides higher alcohols.
c
Due to its carcinogenicity (IARC, 2007), no tolerable concentration was established for ethanol. The values are shown in brackets for comparative
reasons only.

Sample count

100

50

0
0

500

1000

1500

2000

2500

6000

Sum of higher alcohols [g/hl p.a.]

Fig. 1. Histogram of concentrations of higher alcohols in 290 spirit
samples.

As early as 1974, Prokop and Machata (1974)
demanded that food policy should establish maximum limits for higher alcohols, such as have been established for
methanol. In some countries such limits have already been
established. For example, Mexico has regulated Tequila
and some other Mexican spirits. A range was defined
within which the sum of higher alcohols must lie: for
Tequila the minimum is 20 g/hl p.a. and the maximum is
400 g/hl p.a. (Lachenmeier et al., 2006a). In light of our
evaluation the limit of 400 g/hl p.a. is suitable to protect
the consumer from health risk due to higher alcohols.
The European Union should consider establishing similar
limits for alcoholic beverages to improve consumer safety.
We propose that a limit of 1000 g/hl p.a. for the sum of
higher alcohols should be established in distilled spirits,
similar to the current methanol limit.
3.6. Higher alcohols in surrogates: Safe or toxic?
In conclusion, we return to our original question and try
to resolve the discrepancy between ‘‘generally recognized as

safe status” and ‘‘toxicologically relevant levels” of higher
alcohols in surrogate alcohols. McKee et al. (2005) determined 1-propanol, isobutanol and isoamyl alcohol levels
in Russian illegal alcohols (samogons). The maximum concentrations were approximately 50 g/hl p.a. for 1-propanol,
400 g/hl p.a. for isobutanol and 439 g/hl p.a. for isoamyl
alcohol (recalculated from values in mM). In illegal spirits
from Estonia, Lang et al. (2006) determined maximum concentrations of approximately 113 g/hl p.a. for 1-propanol,
158 g/hl p.a. for isobutanol and 351 g/hl p.a. for isoamyl
alcohol (recalculated from values in mM).
In all cases, even those maximum concentrations, which
were determined only in single samples, are below the maximum tolerable concentrations derived from our study. The
scientific basis for describing the higher alcohol levels in
those surrogates as ‘‘relevant” or ‘‘toxic” is so far completely lacking. In regard to the concentrations of higher
alcohols found in our samples of legal alcoholic beverages
that are of equal quantity or higher than in the surrogates
studied by McKee et al. (2005) and Lang et al. (2006), we
can see no different effects arising from higher alcohols
between legal and surrogate alcohols.
The Russian case-control study of Leon et al. (2007)
showed a strong link between use of surrogate alcohols
and all-cause mortality in men. Unfortunately, the exact
pathways underlying this link are far from clear; however,
regarding the current data available in the literature we tend
to exclude higher alcohols as a cause. Therefore, other constituents of alcoholic beverages have to be considered as
possible determinants of toxicity, including acetaldehyde
(Linderborg et al., 2008), ethyl carbamate (Lachenmeier
et al., 2005) or constituents of essential oils (Lachenmeier
et al., 2004, 2006b). The International Agency for Research
on Cancer (IARC) recently has reassessed the carcinogenicity of alcoholic beverages, which was found primarily due to
ethanol itself (IARC, 2007; Baan et al., 2007). However,
there may be further carcinogenic or liver-toxic contaminants in alcoholic beverages and surrogate alcohol products
(besides ethanol, acetaldehyde, and ethyl carbamate, e.g.,
nitrosamines, mycotoxins, lead, cadmium, arsenic), and
there exists the possibility of synergistic effects between

D.W. Lachenmeier et al. / Regulatory Toxicology and Pharmacology 50 (2008) 313–321

ethanol and such other contaminants (Lachenmeier, 2007).
However, it should be kept in mind that most likely part or
all of the detrimental effect of surrogate alcohols may be
entirely due to the effect of ethanol, which itself is strongly
related to different causes of mortality (Rehm et al., 2004).
Conflict of interest statement
None declared. No funding was specific to the production of this manuscript. The salaries for authors were provided by the affiliated organizations.
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