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Ill health effects associated with wood:
Skin:
The main effect is irritation. This can be caused by skin contact
with the wood, its dust, its bark, its sap, or even lichens growing on the
bark. Irritation can, in some species of wood, lead to nettle rashes or
irritant dermatitis. These effects tend to appear on the forearm, back of
the hands, the face (particularly eyelids) neck, scalp and the genitals. On
average, they take 15 days to develop. Symptoms usually only persist as long
as the affected skin site remains in contact with the source of irritation,
e.g. wood dust. Symptoms subside when contact with the irritant is removed.
Sensitisation dermatitis
is more problematic and is usually caused by skin exposure to fine wood dust
of certain species. This is also referred to as allergic contact dermatitis
and results in similar skin effects to those produced by skin irritants.
Once sensitised, the body sets up an allergic reaction, and the skin may
react severely if subsequently exposed to very small amounts of the wood
dust. Cross-sensitisation may develop where other woods or even non wood
materials produce a similar response.
Respiratory and allied effects: Wood,
especially inhalation of fine dust, can have many effects on the respiratory
tract, including :
Nose
The most common effects arise from
irritation, where symptoms usually only persist as long as the sufferer
remains in contact with the irritant. Allergic effects, as a consequence
of sensitisation to wood dust can also occur, e.g. rhinitis.
Lung
-
Asthma
-
Impairment of lung function
-
Rarely - extrinsic allergic alveolitis (a
disease with 'flu-like' symptoms which can cause progressive lung
damage), eg when using western red cedar, iroko.
Asthma
is of particular concern. Most wood dusts can irritate the respiratory
tract provoking asthma attacks in sufferers; although effective control of
dust levels normally improves the problem.
Some wood dusts can cause asthma as a
specific allergic reaction. Once sensitised, the body will quickly
react of subsequently exposed, even to tiny traces of dust. Unlike
irritation, where people can continue to work with the dust once it is
controlled to below the level at which irritation occurs, people who
become sensitised will not normally be able to continue working with the
dust, no matter how low the exposed.
Nose
-
Soreness
-
Watering
-
Conjunctivitis
Whole body: Inhalation
of some wood dusts can have general (whole body) effects,
eg, South African boxwood, although this is not usual for the common
commercial woods. Many effects have been described including headache,
thirst, nausea, visual disturbance, drowsiness, anaemia and hepatitis.
Toxic Activity
Toxic activity is specific to a
wood species. Knowing the exact species is important in establishing
what the potential toxic effects may be. Individual wood species (of
which more than 100 are commercially important in the UK) are very easily
confused. For example, rosewood may be used for up to 30
different species; and an individual species may have up to ten different
trade names. An additional difficulty is that trees vary within a
species. One specimen may contain low levels of its toxic agent and
the next contain much higher levels. So experience may not be a
reliable guide.
Wood Classification
Wood is classified into two broad
families: Hardwood & Softwood
The classification is botanical and depends on the fine structure of the
cells in the wood species. It does not refer to the physical
properties of the wood. For example, balsa wood is a hardwood!
Users should remember that veneers are often made of hardwoods; so are
composite materials such as plywoods. The type of wood making up
particle boards, eg, chipboard, hardboard, MDF is not always known, but is
usually a high proportion of softwood. However MDF sourced from areas
of the world where hardwood predominates, such as Malaysia & Indonesia, will
be more likely to be composed of a high proportion of hardwood.
The HSE have designated both hardwood and softwoods as Asthmagens and
hardwoods as a Carcinogen.
Please see Table 2 of the HSE Woodworking
Information Sheet No. 30, for reported adverse health effects on more common
toxic woods. |
