Understanding Toxicity
Human and ecosystem toxicity has generally been inadequately
dealt with by the building sector in the past and only becomes a
significant focus in an occupational health and safety (OH&S)
context for workers in manufacturing of products and sometimes
building workers. Legislation is almost silent on a mandate of safe
levels of specific problem chemicals in finished products that
might affect end users.
Where some attention has been paid to
it, only volatile organic compounds (VOCs) and specific chemicals
like formaldehyde have been dealt with in any consistent way and
these only in Green Star® and more recently by air measurement of
finished interiors under the NABERS IEQ (National Building
Environment Rating Scheme Indoor Environment Quality) system, While
volatile chemicals evaporating out of interior products and being
inhaled into the respiratory system is undoubtedly a major
influence in human toxicity, there are a whole range of other
toxicity pathways, especially dermal (skin) absorption and
ecosystem toxicities that we largely ignore (and do so at our
peril). The most common source of chemical information on products
is the MSDS (material safety data sheet) as all manufacturers are
required to produce these sources of information by OH&S
legislation.
By examining toxicity over life span (including end-use
disposal) as GreenTag does, LCA assesses the total impact of a
material on current and future generations in terms of both human
and ecosystem health. This is a more complete and balanced approach
to those that address important individual issues such as threats
to occupant health, sourcing, manufacturing biodiversity impacts or
OH&S issues.
While indoor air quality and OH&S are important,
considerations currently being addressed by regulators, a range of
other critical toxicity pathways such as dermal absorption (skin)
and lifecycle ecosystem toxicity including disposal at end of life
also require consideration.
Materials Safety Data Sheets
(MSDSs)
MSDSs are required to be produced by manufacturers to explain in
a standardised format declaring:
i) the types of chemicals that
comprise the product;
ii) the effects of the finished product
on humans and ecosystems;
iii) safety precautions to take in the event
of any accident; and
iv) the manufacturer's contact details.
MSDSs are required by legislation and are a very useful source
of product information. The quality of the data provided in MSDSs
varies. Importantly, the impact of the finished product should
include its individual components and while this is done through
LCA-based product assessment, it is often not undertaken with an
MSDS. A product's components can have significant impacts, in their
own right, before being combined into a product and as the product
breaks down, at end of life.
For example, this is particularly important when we look at
highly toxic components (e.g. monomers that are combined to form
essentially non-toxic compounds such as polystyrene, epoxy, PVC,
synthetic rubber, polyurethane, ABS plastic, etc) where the
potential exists for un-reacted or 'free' monomers to exist after
the polymerisation reaction, as discussed below.
Novel ultra low toxicity
thresholds
Residual free monomer or reactant levels in polymers are an
emerging issue in some plastics, as it has been found that some of
these chemicals can have significant impacts at much lower levels
than previously thought (for example: bisphenol A (BPA) in epoxies
and polycarbonates; vinyl chloride monomer (VCM) in PVCs;
isocyanate, TDI or MDI monomers in polyurethanes; and styrene
monomers in polystyrene, ABS, styrene butadiene rubber (SBR) or
synthetic rubber). Care should be taken to ask for the test results
of finished products from manufacturers for residual un-reacted
monomers when using these products, especially in situations where
skin contact is common.
How are chemical impacts
assessed?
Chemicals are assessed internationally by a variety of bodies in
the European Union (EU) and the USA. Australia has adopted the
European system which is based on EU Directive 67/548/EEC. This is
related to the United Nations' Globally Harmonized System of
Classification and Labelling of Chemicals (GHS), as well as EU
Directive 2001/59/E and REACH programs.
These collectively represent the EU Regulation on the
'Classification, Labelling and Packaging of Dangerous Substances
and Mixtures' and the related EU ESIS or European Chemical
Substances Information System. The system Australia has adopted is
called HSIS or 'Hazardous Substances Information System'. [1] HSIS is an internet resource that allows you to
find information on substances that have been classified in
accordance with the 'Approved Criteria for Classifying
Hazardous Substances'. It is currently based on the EU
Directive 67/548/EEC and is moving towards the adoption of REACH in
the future. In addition to providing powerful search features, HSIS
also provides direct access to a consolidated list of all the
classified substances contained in the HSIS database. The HSIS
database provides searchable access to two data sets, one for
hazardous substance information and the other for exposure standard
information for human health impacts. While HSIS contains
environmental toxicity data, this is not necessarily complete
because its focus is on OH&S, so for accuracy ESIS or the GHS
systems must also be checked. The HSIS can be searched by use of
chemical identifier numbers (called CAS) or UN numbers or
alphabetically.
How to identify Chemicals and
their impacts
Chemicals can be identified via a number of different pathways.
The databases and MSDS will typically include either CAS or UN
numbers or both.
'Chemical Abstract Service' Registry Number (CAS Number)
A 'Chemical Abstract Service' Number (CAS
Number) is a numerical designation assigned to a single chemical.
Mixtures can also be assigned a CAS Number.
United Nations Number (UN Number)
UN Numbers relate to 'Dangerous Goods'
classification and are predominantly intended for transport
information. The UN number is a four digit catalogue number
developed by the UN. They can be assigned to a single substance or
to a group with similar characteristics or hazardous
properties.
CAS and UN numbers identify the chemical, but to describe the
potential impacts of chemicals a variety of indicators such a Risk
Phrases (R-Phrases), Safety Phrases (S-Phrases) and 'Toxicity
Indicators' are used.
R-Phrases (Risk Phrases)
R-Phrases give a general indication of the potential effect of a
chemical. They can be represented by either a number or a phrase
(e.g.' R39 Danger of very serious irreversible effects'). They can
be listed as single numbers to denote separate statements or with
an oblique (/) linking more than one number that denotes a combined
statement of the phrases involved in the impacts of a specific
substance. [2]
S-Phrases (Safety Phrases)
S-Phrases are indicators of precautions that should be taken
when handling a product or its container (e.g. 'S18 Handle and open
container with care').
Classification Indicators
There are also a variety of abbreviations used to classify the
impacts of products as follows:
C Corrosive
E
Explosive
F
Flammable
F+ Extremely Flammable
N Dangerous for
the Environment
|
O
Oxidising
T
Toxic
T+ Very Toxic
Xn
Harmful
Xi Irritant
|

[3]
How to determine if an exposure is dangerous
Toxicity hazard potential is a function of both dose and
exposure. The dose measures used are NOAEL and NOAC and
they are defined as follows:
NOAELs: 'No Observed Adverse Effect Levels' are
the highest doses that don't cause ill-effects. A NOAEL refers to a
dose of chemical that is ingested.
NOAECs: 'No Observed Adverse Effects
Concentration' is the highest level of a chemical
in a toxicity test that did not cause harmful effects to a
plant or animal. A NOAEC refers to direct exposure (e.g. through
the skin or gills).
While NOAELs and NOAECs are similar, they are not
interchangeable. NOAECs and NOAELs are based on tests that
determine the lethal concentration or lethal dose (LC or LD) to a
given indicator plant or animal, under test conditions, that impact
a given percentage of the population. For example, LC50
and LD50 refer to the lethal concentration or dose that
kills 50% of a population under test conditions.
The LD50 is generally expressed as the dose in milligrams (mg)
of chemical per kilogram (kg) of body weight. LC50 is usually
expressed as mg of chemical per volume (e.g. litre or L) of medium
(i.e. air or water) which the organism is exposed to. Chemicals are
considered highly toxic when the LD50/LC50 is small and practically
non-toxic when the value is large. However, the LD50/LC50 does not
reflect any effects from long-term exposure (i.e. cancer, birth
defects or reproductive toxicity) that may occur at levels below
those that cause death. [4]
NOAEL/NOAEC levels or LC/LD toxicity data are not usually, in
themselves, able to assess the toxicity risk levels of products in
manufacture, use (except for VOCs or similar cases) or disposal
without measures or systems for exposure and/or the likelihood or
risk of a critical exposure. To assess the exposure thresholds,
other measures are used.
TWA (ppm or mg/m3)
The TWA is the 'time-weighted average' concentration for a
normal 8-hour workday or 40-hour work week.
STEL (ppm or mg/m3)
The STEL (Short Term Exposure Limit) is the maximum
concentration of a substance (a) for a continuous 15-minute
exposure period, (b) for maximum of 4 such periods per day, (c)
with at least one 60-minute exposure-free period between two
exposure periods, and (d) provided the daily TLV-TWA is met. [5]
What are the issues?
Typically each key area of health impact has a 2-4 tier scale of
impact in EU or UN based systems:
Human Health
Chemicals in the 'Persistent Organic Pollutants' (POPs) category
are banned internationally under the Stockholm Convention. Highly
hazardous pesticides and industrial chemicals are also banned under
Annexure III of the Rotterdam Convention.
But there are other substances of lesser impacts that have been
classified to help us determine the safe levels of exposure for
humans and for ecosystems. Below are the major ones likely to be
relevant to most home owners and building professionals. They are
defined as follows:
Toxicity: To indicate how these are
determined, the EU defines chemicals as toxic when they are
classified as carcinogenic (category 1A or 1B), mutagenic (category
1A or 1B), or toxic for reproduction (category 1A, 1B, or 2).
According to the US EPA the word definitions of toxicity categories
are subdivided as follows:
- Category I: Highly toxic; severely
irritating
- Category II: Moderately toxic; moderately
irritating
- Category III: Slightly toxic; slightly
irritating
- Category IV: Practically non-toxic; not an
irritant [6]
Some toxins can also be classified as persistent and very
persistent, bio-accumulative and very bio-accumulative (see R
Phrases).
Carcinogens: Substances capable of causing
cancer. Chemicals classified by the 'International Agency on
Research into Cancer' (IARC) are:
- Category 1 Carcinogenic to humans
- Category 2A Probably carcinogenic to
humans
- Category 2B Possibly carcinogenic to
humans
- Category 3A Not classifiable as to
carcinogenicity to humans-tested
- Category 3B Not classifiable as to
carcinogenicity to humans-untested
- Category 4 Probably not carcinogenic to humans
[7]
Mutagens: Substances capable of impairing or
modifying genes.
- Category 1 Known to be mutagenic to
humans
- Category 2 Should be regarded as if they are
mutagenic to humans
- Category 3 Cause possible mutagenic concern
for humans
Teratogens: Substances toxic to reproduction
(developmental toxicity or impairment of fertility).
- Category 1 Known to be toxic to reproduction
in humans
- Category 2 Should be regarded as if they are
toxic to reproduction in humans
- Category 3A Cause possible developmental
toxicity for humans
- Category 3B Cause possible impairment of
fertility for humans
Sensitisers: Are divided into two
categories:
i) a respiratory sensitiser is a
substance that will induce hypersensitivity of the airways
following inhalation of the substance.
ii) a contact sensitiser is a substance
that will induce an allergic response following skin contact.
The EU only ascribes one category to skin sensitisers but the US
OSHA [8] divides Category 1 sensitisers into 2
sub-categories as follows:
Respiratory Sensitiser Categories:
- Category 1A: Substances showing a high
frequency of occurrence in humans; or a probability of occurrence
of a high sensitization rate or severity of reaction in humans (May
cause allergic or asthmatic symptoms or breathing difficulties if
inhaled [Respiratory Sensitiser EU])
- Category 1B: Substances showing a low to
moderate frequency of occurrence in humans; or a probability of
occurrence of a low to moderate sensitization or severity of
reaction (May cause allergic or asthmatic symptoms or breathing
difficulties if inhaled [Respiratory Sensitiser EU])
Contact Skin Sensitiser Categories:
- Category 1A: Skin Sensitiser - May cause
allergic skin reaction (≥ 0.1%)
- Category 1B: Skin Sensitiser - May cause
allergic skin reaction (≥ 1.0%)
The US based OSHA organisation also has some additional skin and
eye related categories: [9]
Skin Corrosion
- Category 1A: serious irreversible effects on
skin (≤ 3 min, observed ≤ 1hour)
- Category 1B: serious irreversible effects on
skin (> 3 min ≤ 1 hour, observed ≤ 14 days)
- Category 1C: serious irreversible effects on
skin (> 1 hour ≤ 4 hours observed ≤ 14 days)
Skin Irritant:
- Category 2: reversible irritations to
skin
Eye Corrosiveness
- Category 1: serious irreversible effects to
eyes
- Category 2A: irritating to eyes
- Category 2B: mildly irritating to eyes
Endocrine disruptors:
A whole variety of chemicals in common use today disrupt human
and animal hormones. Some do this by mimicking the hormone
oestrogen. They can cause developmental defects such as sperm loss,
breast tissue growth in males, sex conversion in animals and
recently they have begun to be linked to breast cancer. Such
chemicals typically are used as plasticisers e.g. DOP and other
phthalates in vinyls (now banned in children's toys) and other
chemicals such as BPA found in polycarbonates and epoxies. The EU
defines endocrine disruptors as follows:
- Category 1: evidence of
endocrine disrupting activity in at least one species using intact
animals;
- Category 2: at least some
laboratory evidence of biological activity related to endocrine
disruption;
- Category 3: no evidence of endocrine
disrupting activity or no data available [10]
Within ESCAP, categories where 'No data is available' trigger
closer inspection and more detailed research and the 'precautionary
principle ' is carefully considered in the risk assessment stage
(see below for more information).
Ecological Health
issues
Substances with the classifications listed above are obviously
all still relevant in ecosystem health. However, in water based
ecosystems, other criteria also become relevant.
Eutrophication
This is the process by which a body of water acquires a high
concentration of nutrients, especially phosphates and nitrates.
These typically promote the excessive growth of algae. As the algae
die and decompose, high levels of organic matter and the
decomposing organisms deplete the water of available oxygen,
causing the death of other organisms, such as fish. Eutrophication
is a natural, slow-aging process for a water body, but human
activity can greatly speed up and intensify this process. [11]
Figure: Example of algal blooms from eutrophication [12]
Acidification
Acidification occurs in air when compounds like sulphur or
nitrogen (and their oxides or ammonia) are emitted, typically from
fossil fuel energy generation or from industrial, petrochemical and
vehicular pollution.
Acidification typically occurs in soils when acid
rain falls, or through the overuse of synthetic nitrogen
fertilisers, or due to poor land management practices.
In lakes and streams, it can occur from direct deposition of
pollutants into lakes and streams or, more commonly, through runoff
and soil erosion from the surrounding areas.
It can also occur in oceans when increased levels of carbon
dioxide (from human or natural processes) dissolve in the surface
waters of the ocean, forming a solution of carbonic acid.
Increasing an ocean's acidity reduces the ability of organisms to
calcify their shells.
Figure: Example of trees killed by
acid rain [13]
How to determine if a
substance or mixture is harmful
To determine whether a substance or mixture is
hazardous, using the HSIS, we must follow this approach:
Step 1: Identify each
ingredient using the substance name, CAS Number or UN number
Step 2: Determine if the
concentration of any ingredient is above the minimum concentration
cut-off level (if so, the mixture is determined to be
hazardous).
If any ingredient in the mixture does not appear on the HSIS, or
is listed without at least one concentration cut-off level, then we
must check other databases such as ESIS or GHS. If a mixture
contains more than one ingredient that is in the HSIS consolidated
listing, and all ingredient concentrations are below their
respective minimum concentration cut-off levels, the mixture may
still be considered hazardous if one or more of these ingredients
exhibit corrosive, irritant or acute lethal effects.
The Precautionary Principle
The precautionary principle or precautionary
approach states that if an action or policy has a suspected risk of
causing harm to the public or to the environment, in the absence of
scientific consensus that the action or policy is harmful, the
burden of proof that it is not harmful falls on those
taking the action.
This principle allows policy (and Standard) makers to make
discretionary decisions in situations where there is the
possibility of harm from taking a particular course or making a
certain decision when extensive scientific knowledge on the matter
is lacking. The principle implies that there is a social
responsibility to protect the public from exposure to harm, when
scientific investigation has found a plausible risk. These
protections can be relaxed only if further scientific findings
emerge that provide sound evidence that no harm will
result.
In some legal systems, as in the law of the European Union, the
application of the precautionary principle has been made a
statutory requirement. [14]

How the ecolabels deal
with chemical impacts
Global
GreenTagCertTM
The Global GreenTagCertTM Standard does not allow the
use of its label if a product contains certain very toxic and
persistent chemicals or categories of chemicals. A broader group is
not accepted beyond a 0.1% threshold limit, subject to risk
assessment. Global GreenTagCertTM then divides all
remaining chemicals into categories by R-Phrase and assesses and
scores them by threshold and a range of exposure limits and risk
evaluation. There are then specific supplementary standards where
the cut-off levels vary with the application, with the more
critical applications reducing the threshold values even further to
0.001%. Passing the toxicity criteria is mandatory if the product
is to be allowed to carry the label.
Furntech Green Tick
The Furntech Green Tick Standard does not allow the use of its
label if a product contains some specific chemicals and categories
of chemicals such as very toxic chemicals and APEOs, heavy metals
to NAOELs and carcinogens to 0.1%. A chemical management plan is
used that identifies toxic chemicals and ensures safe handling
procedures. The range of R-Phrases assessed is less broad than
either GECA or GreenTag. Passing the toxicity criteria is
mandatory, if a product is to be allowed to carry the label.
Carpet Institute ECS
The ECS scheme does not allow the use of its label if a product
contains very toxic compounds, Group 1 and 2A carcinogenic,
mutagenic and teratogenic compounds. It also restricts the use of
its label if 378 specific chemicals on the REACH 'SIN' list to a
0.1% threshold value. It requires the presence of heavy metals to
comply with NOAEL levels and free monomer residues to 10mg/kg of
polymer weight (0.001%). Passing the toxicity criteria is mandatory
if a product is to carry the label, except for level 1 which only
assesses VOCs and does not look at any toxicity requirements for
raw materials.
SMaRT
Use of the SMaRT Standards label is only allowed if Stockholm
Convention Persistent Organic Pollutants are not present at more
than 0.1% in the product. Likewise, carcinogens, VOCs and several
other specific chemicals cannot be present in products if they are
to be labelled with a SMaRT label. Credits are given for
inventorying over 1200 listed chemicals and achieving voluntary
reductions. No specific minimum threshold values for these
chemicals are required, before a SMaRT label is allowed to be
used.
GECA
Depending on the standard used, GECA labels cannot be used if
the product contains certain very toxic and persistent chemicals or
categories of chemicals. GECA selects a limited range of specific
R-Phrases and uses 0.1% cut-off levels for a pass/fail assessment.
The cut-off levels vary with the application, with more critical
applications reducing the threshold values. Passing the toxicity
criteria is mandatory if the product is to be allowed to carry the
label.
Ecospecifier Verified
Similar to Global GreenTagCertTM the Ecospecifier
Verified Products Standard label cannot be used on products
containing certain very toxic and persistent chemicals and
categories of chemicals. Likewise, labelling is not allowed if a
broader group of chemicals is present beyond a 0.1% threshold
limit, subject to risk assessment. It then divides all remaining
chemicals into categories by R-Phrase and assesses and scores them
by threshold and a range of exposure limits and risk evaluation.
There are then specific supplementary standards where the cut-off
levels vary with the application, with the more critical
applications reducing the threshold values even further to 0.001%.
Passing the toxicity criteria is mandatory if the product is to be
allowed to carry the label. All toxicity and environmental claims
are assessed in accordance with ISO 14021.
References
All last accessed on 1/8/12.