140. Sulphuric, hydrochloric, nitric and phosphoric acids

129 Pages·2009·0.78 MB·English

nr 2009;43(7)
The Nordic Expert Group for Criteria Documentation
of Health Risks from Chemicals
140. Sulphuric, hydrochloric,
nitric and phosphoric acids
Marianne van der Hagen
Jill Järnberg
arbete och hälsa | vetenskaplig skriftserie
isbn 978-91-85971-14-5 issn 0346-7821
Arbete och Hälsa
Arbete och Hälsa (Work and Health) is a scientific
report series published by Occupational and
Enviromental Medicine at Sahlgrenska Academy,
University of Gothenburg. The series publishes scientific
original work, review articles, criteria documents
and dissertations. All articles are peer-reviewed.
Arbete och Hälsa has a broad target group and
welcomes articles in different areas.
Instructions and templates for manuscript editing
are available at http://www.amm.se/aoh
Summaries in Swedish and English as well as
the complete original texts from 1997 are
also available online.
Arbete och Hälsa Editorial Board:
Editor-in-chief: Kjell Torén Tor Aasen, Bergen
Kristina Alexanderson, Stockholm
Co-editors: Maria Albin, Ewa Wigaeus Berit Bakke, Oslo
Tornqvist, Marianne Törner, Wijnand Lars Barregård, Göteborg
Eduard, Lotta Dellve och Roger Persson Jens Peter Bonde, Köpenhamn
Managing editor: Cina Holmer Jörgen Eklund, Linköping
Mats Eklöf, Göteborg
© University of Gothenburg & authors 2009 Mats Hagberg, Göteborg
Kari Heldal, Oslo
Arbete och Hälsa, University of Gothenburg Kristina Jakobsson, Lund
SE 405 30 Gothenburg, Sweden Malin Josephson, Uppsala
Bengt Järvholm, Umeå
ISBN 978-91-85971-14-5 Anette Kærgaard, Herning
ISSN 0346–7821 Ann Kryger, Köpenhamn
http://www.amm.se/aoh Carola Lidén, Stockholm
Printed at Reproservice, Chalmers Svend Erik Mathiassen, Gävle
Gunnar D. Nielsen, Köpenhamn
Catarina Nordander, Lund
Gunnar Ahlborg, Göteborg
Torben Sigsgaard, Århus
Staffan Skerfving, Lund
Kristin Svendsen, Trondheim
Gerd Sällsten, Göteborg
Allan Toomingas, Stockholm
Ewa Wikström, Göteborg
Eva Vingård, Uppsala
Preface
The main task of the Nordic Expert Group for Criteria Documentation of Health
Risks from Chemicals (NEG) is to produce criteria documents to be used by the
regulatory authorities as the scientific basis for setting occupational exposure
limits for chemical substances.
For each document, NEG appoints one or several authors. An evaluation is
made of all relevant published, peer-reviewed original literature found. The
document aims at establishing dose-response/dose-effect relationships and
defining a critical effect. No numerical values for occupational exposure limits
are proposed.
Whereas NEG adopts the documents by consensus procedures, thereby granting
the quality and conclusions, the authors are responsible for the factual content of
the document.
The evaluation of the literature and the drafting of this document were made
by Cand. Scient Marianne van der Hagen at the Norwegian Pollution Control
Authority, and Dr. Jill Järnberg at the Swedish Work Environment Authority. The
draft document was discussed within the group and the final version was accepted
by NEG on April 1, 2008 as its document. The following individuals participated
in the elaboration of the document:

Gunnar Johanson Institute of Environmental Medicine, Karolinska Institutet, Sweden
(chairman)
Maria Albin Department of Occupational and Environmental Medicine, University
Hospital, Lund, Sweden (former NEG expert)
Karin Sørig Hougaard National Research Centre for the Working Environment, Denmark
(former NEG expert)
Kristina Kjærheim Cancer Registry of Norway (NEG expert)
Tiina Santonen Finnish Institute of Occupational Health, Finland (NEG expert)
Vidar Skaug National Institute of Occupational Health, Norway (NEG expert)
Jill Järnberg and Swedish Work Environment Authority, Sweden (NEG secretariat)
Anna-Karin Alexandrie

Editorial work and technical editing were performed by the NEG secretariat.
This work was financially supported by the former Swedish National Institute for
Working Life, The Swedish Work Environment Authority, the Norwegian
Ministry of Labour and Social Inclusion and the Nordic Council of Ministers.
All criteria document produced by NEG may be downloaded from
www.nordicexpertgroup.org.

Gunnar Johanson, Chairman of NEG
Contents
Preface
Abbreviations and acronyms
1. Introduction 1
2. Substance identification 1
3. Physical and chemical properties 2
4. Occurrence, production and use 4
5. Measurements and analysis of workplace exposure 6
6. Occupational exposure data 8
7. Toxicokinetics 14
7.1 Deposition 14
7.2 Uptake 15
7.3 Distribution 15
7.4 Biotransformation and excretion 15
8. Biological monitoring 15
9. Mechanisms of toxicity 16
10. Effects in animals and in vitro studies 17
10.1 Irritation, corrosion and sensitisation 17
10.2 Effects of single exposure 20
10.3 Effects of short-term exposure (up to 90 days) 32
10.4 Mutagenicity and genotoxicity 39
10.5 Effects of long-term exposure and carcinogenicity 39
10.6 Reproductive and developmental effects 47
11. Observations in man 47
11.1 Irritation, corrosion and sensitisation 47
11.2 Case reports 48
11.3 Effects of single and short-term exposure 50
11.4 Effects of long-term exposure 63
11.5 Genotoxic effects 66
11.6 Carcinogenic effects 70
11.7 Reproductive and developmental effects 72
12. Dose-effect and dose-response relationships 81
12.1 Sulphuric acid 81
12.1.1 Single/short-term exposure 81
12.1.2 Long-term exposure 83
12.2 Hydrochloric acid 89
12.2.1 Single/short-term exposure 89
12.2.2 Long-term exposure 90
12.3 Nitric acid 91
12.3.1 Single/short-term exposure 91
12.3.2 Long-term exposure 93
12.4 Phosphoric acid 93
13. Previous evaluations by national and international bodies 93
13.1 Sulphuric acid 93
13.2 Hydrochloric acid 95
13.3 Nitric acid 95
13.4 Phosphoric acid 96
14. Evaluation of human health risks 96
14.1 Assessment of health risks 96
14.2 Groups at extra risk 100
14.3 Scientific basis for an occupational exposure limit 100
15. Research needs 102
16. Summary 103
17. Summary in Norwegian 104
18. References 105
19. Data bases used in the literature search 118
Appendix 1. Occupational exposure limits 119
Appendix 2. Previous NEG criteria documents 120
Abbreviations and acronyms

ACGIH American Conference of Governmental Industrial Hygienists
ARDS acute (or adult) respiratory distress syndrome
ATSDR Agency for Toxic Substances and Disease Registry
CI confidence interval
DECOS Dutch Expert Committee on Occupational Safety
DFG Deutsche Forschungsgemeinschaft (German Research Foundation)
FEF forced expiratory flow at x % of FVC
x
FEV forced expiratory volume in one second
1
FVC forced vital capacity
IARC International Agency for Research on Cancer
IOM Institute of Occupational Medicine, Edinburgh, United Kingdom
IPCS International Programme on Chemical Safety
LC lethal concentration for 50 % of the exposed animals at single exposure
50
LOAEL lowest observed adverse effect level
MD median diameter
MMAD mass median aerodynamic diameter
MMD mass median diameter
NEG Nordic Expert Group for Criteria Documentation of Health Risks from
Chemicals
NIOSH National Institute for Occupational Safety and Health (United States)
NOAEL no observed adverse effect level
OR odds ratio
PM particulate matter with aerodynamic diameter up to x µm
x
RADS reactive airways dysfunction syndrome
RD air concentration associated with a 50 % decrease in the respiratory rate
50
of animals
RR relative risk (risk ratio)
SCOEL Scientific Committee on Occupational Exposure Limits (European
Union)
SG specific airway conductance
aw
SIR standardised incidence ratio
SMR standard mortality ratio
STEL short-term exposure limit
TNFα tumour necrosis factor alpha
TWA time-weighted average
VMD volume median diameter
WHO World Health Organization
1. Introduction
Inorganic acids are of prime importance in the chemical and metal industries.
They are used as raw materials in the manufacture of a wide range of chemicals,
as well as in refining, electrolysis and extraction in chemical processes. Inorganic
acids are widely used in the pickling processes of electroplating, in vehicle
production plants and in steel producing plants.
The present document concerns the effects of four inorganic acids: sulphuric
acid (H SO ), hydrochloric acid (HCl), nitric acid (HNO ) and phosphoric acid
2 4 3
(H PO ). It does not consider sulphur dioxide, nitrous gases, or phosphorous
3 4
compounds such as phosphorous pentoxide and red phosphorus, which may be
converted to phosphoric acid.
A previous NEG document published in 1993 described the effects of aerosols
of these four acids (142). The biological effects of H SO are relatively well
2 4
investigated, whereas the documentation concerning the effects of the other three
acids, discussed in this document, is limited.
Acid concentrations are given in mg/m3. Data originally reported in units of
ppm have been converted to units of mg/m3 by using the conversion factors given
in Table 2. Occasionally, the originally reported ppm values are also given.
2. Substance identification
Substance identification data for the inorganic acids dealt with in this document
are given in Table 1.
Although anhydrous sulphuric and nitric acids can be produced, the chemical
names usually refer to aqueous solutions of the compounds.
Hydrochloric acid is the aqueous solution of hydrogen chloride gas. In this
document, the chemical formula HCl may denote hydrochloric acid as well as
hydrogen chloride gas.

Table 1. Substance identification data of the inorganic acids (142).

Common name CAS No. Synonyms Molecular Molecular
formula weight

Sulphuric acid 7664-93-9 Battery acid, dipping acid, H SO 98.08
2 4
electrolyte acid, fertiliser acid,
hydrogen sulphate, matting acid,
Nordhausen acid, oil of vitriol,
spirit of sulphur, sulfuric acid
Hydrochloric acid 7647-01-0 Hydrogen chloride, chlorohydric HCl 36.46
acid, hydrochloride, muriatic acid,
spirits of salt
Nitric acid 7697-37-2 Aqua fortis, azotic acid, hydrogen HNO 63.02
3
nitrate
Phosphoric acid 7664-38-2 Orthophosphoric acid H PO 98.00
3 4

1
Phosphoric acid, when pure, is a solid at room temperature and normal pressure.
However, an aqueous solution of 85 % H PO is a viscous liquid. In this document,
3 4
H PO refers to aqueous solutions of the solid compound.
3 4
3. Physical and chemical properties
Data on physical and chemical properties are presented in Table 2. H SO ,HCl
2 4
and HNO are all strong acids, and dissociate completely in water at moderate
3
concentrations. HCl is the strongest acid (indicated by the lowest pK ) followed
a
by H SO and HNO . H PO is the weakest of the acids. All four acids are hygro-
2 4 3 3 4
scopic (attract water molecules from the surrounding environment) and corrosive
to (destroy or irreversibly damage) living tissue. HNO and concentrated H SO are
3 2
strong oxidising agents.
Solutions of the acids are not flammable in themselves. However, contact with
metals may release flammable and explosive hydrogen gas (H ).
2
The physical state of the acids in workplace air ranges from primarily liquid
aerosols for the non-volatile H SO and H PO to liquid aerosols and vapours
2 4 3 4
for the more volatile HCl and HNO (37). There are a number of definitions of
3
aerosols that are used in a wide variety of contexts. IUPAC defines an aerosol as
a mixture of small (diameter 0.01-100 µm) solid or liquid particles and a carrier
gas (usually air). A droplet is defined as a small liquid particle and a mist as a
suspension of droplets in a gas. Also fog is used as a general term applied to a
suspension of droplets in a gas (119). Other kinds of aerosols are dust, fume,
smoke, haze, and smog (190).
In the present document the original wording regarding aerosols in the cited
papers is retained.
Sulphuric acid
H SO is a colourless (when pure) to dark brown, oily liquid. It is odourless un-
2 4
less heated (then pungent). Cold H SO reacts with most metals and the reactivity
2 4
increases upon heating. The acid can release flammable hydrogen gas when in
contact with metals. H SO is highly corrosive, a property accentuated by its
2 4
highly exothermic (generates heat) reaction with water. H SO is an excellent
2 4
dehydrating agent. Its affinity for water is sufficiently strong to remove hydrogen
and oxygen atoms from other compounds. Fuming H SO (oleum) is a solution of
2 4
the anhydride sulphur trioxide (SO ) in anhydrous H SO . In air, sulphur trioxide
3 2 4
vapour is rapidly converted to a stable mist of droplets of the acid by reacting with
atmospheric moisture (6, 96, 110, 180).
Hydrochloric acid
HCl is a colourless fuming liquid with a pungent irritating odour. The mixture of
HCl gas and water has a constant-boiling azeotrope at 20 % HCl. It is a very stable
compound but decomposes at high temperatures into hydrogen and chlorine. HCl
reacts violently with bases and is corrosive. It also reacts violently with oxidants
2
Table 2. Physical and chemical properties of the inorganic acids (3-6, 19, 74, 75, 129, 142, 143, 188).

Property Sulphuric acid (H SO ) Hydrochloric acid (HCl) Nitric acid (HNO ) Phosphoric acid (H PO )
2 4 3 3 4

Description Colourless (pure) to dark Colourless to slightly yellow, Clear, colourless liquid; Clear, colourless, syrupy
brown, oily liquid; odourless fuming liquid; pungent irritating suffocating odour liquid (<85 %); odourless
unless heated, then pungent odour
Boiling point (°C) 338 (98 %, aqueous solution) 110 (20 %) 121 (70 %) 158 (85 %)
-85 (gas) 86 (100 %, decomposes) 261 (solid)
Melting point (°C) 10 (100 %) - 85 (25 %) - 42 (70 %) 21 (85 %)
-114 (gas) 42 (solid)
Vapour pressure (kPa) at 20 °C < 0.04 1.5 1.2 0.3
Vapour density (air=1) 3.4 1.3 1.4 3.4
Density (g/ml) at 25 ˚C 1.84 (100 %) 1.19 (38 %) 1.41 (70 %) 1.71 (85 % )
1.86 (solid)
Solubility in water Complete Complete Complete Complete
Solubility in organic solvents Soluble in ethanol Very soluble in alcohols, soluble No data on solubility in Soluble in ethanol
in ether and benzene, insoluble in ethanol, soluble in ether
hydrocarbons
Octanol/water partition -2.20 (estimated) 0.54 (estimated) 0.21 (estimated) -0.77 (estimated)
coefficient (log P ) a
ow
pK-value b, c -3.0, 1.99 -8.0 -1.3 2.12, 7.21, 12.32
a
Odour threshold (mg/m3) > 1 Range 1-50 0.75-2.50 No odour

Conversion factors in air 1 mg/m3 = 0.25 ppm 1 mg/m3 = 0.7 ppm 1 mg/m3 = 0.4 ppm 1 mg/m3 = 0.25 ppm
(25 °C, 101.3 kPa) 1 ppm = 4.0 mg/m3 1 ppm = 1.4 mg/m3 1 ppm = 2.5 mg/m3 1 ppm = 4.0 mg/m3
a Data from Syracuse Research Corporation’s LogKow (KowWin) Program.
5 b Data from Harvard University, Evans Group, substrate H O. Values < 0 were extrapolated.
2
c H SO : Two pKa-values as it releases two hydrogen ions. H PO : Three pKa-values as it releases three hydrogen ions.
2 4 3 4
3
forming toxic chlorine. On contact with air it emits corrosive fumes. HCl attacks
nearly all metals under release of hydrogen gas. A mixture of concentrated HCl
and a strong oxidising agent dissolves gold, e.g. aqua regia, which is a 3:1 (v/v)
mixture of concentrated HCl and HNO (96, 110).
3
Nitric acid
Pure anhydrous HNO is a transparent, colourless liquid with a characteristic
3
choking odour and in moist air a white fuming liquid. In the presence of light or
by heating, HNO readily decomposes. The vapours formed are a mixture of
3
HNO and decomposition products such as nitrogen oxides (NO ), oxygen and
3 x
water. Nitrogen dioxide (NO ) accounts for the red-brownish (yellow at low
2
concentrations) colour that develops in the acid on standing. HNO is highly
3
corrosive and attacks most substances and all metals except the noble ones and
certain alloys. Reactions with metals may produce nitrous gases and ammonia.
Hydrogen gas is rarely formed. HNO forms a constant boiling mixture with
3
water. Concentrated HNO (~70 %) is a powerful oxidising agent and reacts with
3
combustible, organic and readily oxidisable materials. The reactions are often
highly exothermic and explosive. Aqueous solutions of > 45 % HNO may
3
spontaneously ignite organic materials such as wood and straw (3, 96, 110, 129,
209).
Phosphoric acid
Pure anhydrous H PO is an odourless white solid that melts at 42 °C to form a
3 4
clear, colourless, viscous liquid. At room temperature, an 85 % aqueous solution
of H PO is likewise a clear, colourless, viscous liquid. Besides its acidic
3 4
behaviour, H PO is relatively unreactive at room temperature (74).
3 4
4. Occurrence, production and use
The four inorganic acids in this document are all important industrial chemicals
used in a wide variety of industries/trades and products.
Sulphuric acid
H SO is made as a by-product of other operations or directly from elemental
2 4
sulphur, spent (contaminated and diluted) H SO , and hydrogen sulphide.
2 4
Elemental sulphur is by far the most widely used raw material. Concentrated
H SO is ca 96-98 % (w/w) (18 M). Battery acid used in lead-acid batteries
2 4
is 33.5 %, chamber or fertiliser acid 62-68 %. Fuming H SO , also called oleum,
2 4
is a solution of sulphur trioxide in anhydrous H SO . H SO is used in batteries,
2 4 2 4
pH-regulation agents, electroplating agents, process regulators, cleaning/washing
agents, complexing agents, and in surface treatment and laboratory chemicals.
H SO is also used in the manufacture of chemicals (e.g. titanium dioxide
2 4
pigments), fertilisers, basic metals, pulp and paper, metal products, food products
and beverages, electrical machinery and apparatuses, and in purification of water
4