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Emission of chemical substances from products made of exotic wood

6 Assessment of Emissions

• 6.1 Results
  • 6.1.1 Compounds Emitted to the Air
• 6.2 Assessment of Emissions of Individual Compounds
• 6.3 Assessment of the Total Emissions
  • 6.3.1 Compounds emitted by Migration of Artificial Saliva
• 6.4 Health Assessment of Elements
  • 6.4.1 Assessment of Risk of Allergic Reactions

The assessment of potential comfort and health effects from emissions from compounds from products made of exotic wood comprises exposure to inhalation, contact and migration into artificial saliva. The assessment is based on toxicological principles and data from the literature. At the assessment the basis is a typical scenario from the home.

The impact of exotic wood products to the indoor air was assessed by:

A sum of concentrations in the indoor environment, c, divided by "the lowest concentration of interest" (LCI) and an indoor-relevant time-value based on odour and irritation thresholds, see the definition in paragraph 4.7.1.

The assessments of the wood products examined appear from Tables 22-26 and from the summary in Table 27. Results in detail for the quantified individual compounds appear from Appendix C.

6.1 Results

6.1.1 Compounds Emitted to the Air

Table 22 Lacquered dining table, rubber tree (Hevea brasiliensis)

Table 23 Stained Venetian blind, ramin (Gonystylus bankanus)

Table 24 Waxed bed table, sheesham (Dalbergia latifolia)

Table 25 Oiled floor, merbau (Intsia bijuga)

Table 26 Kitchen table top, iroko (Chlorophora excelsa)

Table 27 Breakdown of wood materials examined on basis of S-value and indoor-relevant time-value

6.2 Assessment of Emissions of Individual Compounds

By the climate chamber measurements of the 5 examined wood species (with or without surface treatment) 7 individual compounds (iroko), 12 individual compounds (ramin), 14 individual compounds (sheesham), 15 individual compounds (merbau) and 17 individual compounds (rubber tree) were found in the emission. Totally 25 individual compounds were demonstrated by the climate chamber measurements. There were thus more individual compounds, which could be retrieved in more of the products. There were only very few compounds in the emissions from the examined wood species, in which it appeared that health effects of the compounds (cancer, allergy, congenital malformation and nervous system effects) had an effect in relation determination of the LCI-value.

For formaldehyde the effects cancer and irritation had an effect in relation to the total assessment of the emissions. The assessment is for formaldehyde based on recommendations from WHO and is less restrictively determined than all the other individual compounds.

Acetaldehyde has like formaldehyde two significant effects, cancer and irritation, where the irritative effect occurs at significantly higher concentrations than for formaldehyde. The risk of cancer is, furthermore, less documented.

Acrolein is assessed to have both an irritative and allergen effect.

For 2-methyl-1-propanol, 3-methylhexane and toluene the LCI-value is determined on basis of the neurotic effects of the individual compounds in question.

For the remainder individual compounds, the LCI-values are based on their irritative effects, see Table 22-26.

6.3 Assessment of the Total Emissions

The examined products were assessed health-wise by determination of the S-value on basis of LCI-values and on basis of comfort considerations by the indoor-relevant time-value. The comfort effects include odour and mucous membrane irritation.

The assessment of the examined exotic wood species and their potential surface treatment appear from the summaries in Tables 22-26. Values for emission have been measured after 3, 10 and 28 days.

The S-value appears for the individual products on basis of a loading of 0.4 m²/m³ corresponding to a wood-based material in a room corresponding to a floor or a table and 6 chairs.

The S-values vary for the 3-days measurement for the 5 products (iroko, ramin, sheesham, merbau and rubber tree) between 0.1 and 1.2, where rubber tree has the highest S-value. (An S-value below 1 is considered to be unproblematic). By the measurements on day 10 S-values were found, which for the 5 products varied between 0.1 and 1.4.

Rubber tree still had the highest S-value. The increase in S-value for rubber tree was based on identification of acrolein in the second sample (day 10) and not in the first (day 3). The result of the measurement is safe, it can, however, not be explained, why acrolein was not demonstrated by the first measurement. By measurements after 28 days the values had dropped further. At that time the S-values for all products - rubber tree, too – were below 1.

The stated measurements thus show a picture indicating that emission of individual compounds from the examined exotic wood species or their surface treatments only take place to a limited extent. None of the products will at the stated emission concentrations cause health effects.

Rubber tree is the only product examined which as an S-value, which in the measurement period exceeds 1. The individual compounds important in relation to the calculated S-values, are formaldehyde and acrolein. It is less probable that they are components of the rubber tree itself. There is every probability that they origin from the surface treatment.

The problems in question with the emission from the rubber tree could thus be solved by substituting the surface treatment or leave the product to emit unpacked 1 month before the customer brings it at home.

6.3.1 Compounds emitted by Migration of Artificial Saliva

The assessment of the 3 compounds occurring at the highest concentration in the two specimens and allergen compounds are listed in Tables 28 and 29. These compounds are in this case chosen on basis of an impression that it would give "worst case" scenario. No information has been found, which describes how much of a wood product a child can consume by sucking or chewing at it.

Table 28 Chemical compounds emitted by migration into artificial saliva from a lacquered table top, Hevea brasiliensis

Table 29 Chemical compounds emitted by migration into artificial saliva from an ink treated figure, Albiz(z)ia falcata

The determination of compounds migrated into artificial saliva was carried out to assess the intake of compounds, which possibly may occur by children sucking and biting at the products. The examination was carried out by migration to 25 ml artificial saliva, as described in paragraph 4.5.

In this context the LCI-values can not be used. In stead calculations of TDI-values have been carried out. TDI (Tolerable Daily Intake) states the amount of chemical pollution, which a human being daily can consume through an entire life without constituting a health risk and the value is determined on basis of the knowledge, which is available on the toxicological properties.

On basis of the toxicological examinations the highest dose is determined, which does not cause demonstrable harmful effects in the most sensible animal species (NOAEL). The safety factor, SF, is normally 100, but in the cases, where no NOAEL is available, but only LOAEL (the lowest dose, which can cause a demonstrable harmful effect) and TD50 (the dose, which is toxic to 50% of a species) the factor has been determined at 1000 or higher. TDI has only been calculated for the 3 compounds occurring in the highest concentration in the 2 examined specimens.

As appears from the following calculation none of the compounds will occur in concentrations exceeding the TDI-value. In a worst case calculation it is estimated that a child weighing 10 kg, consume the entire amount of saliva from 1 gram specimen a day. For 2-butoxy-ethanol 171 g/g specimen was found corresponding to 171 μg/10 kg body weight/day, which corresponds to 0.017 mg/kg/day. The TDI-value for 2-butoxy-ethanol is 0.3 mg/kg/day.

None of the compounds (in 1 gram test material), which occur in concentrations that exceed the calculated TDI-values, see Tables 28 and 29. On the contrary compounds occur in both the products, which are listed on the list of The Danish Working Environment Service for allergy and sensitivity producing compounds in the working environment, including vanillin and phthalic acid anhydride.

Generally, it is considered inappropriate that products emit allergy-producing compounds.

Furthermore, it is considered inappropriate that phthalates such phthalic acid monobutyl ester and diethylphthalat are emitted from the products.

The problem is, of course, of most importance, if the products are used to store food (salad bowls, chopping boards, kitchen table tops etc.) or if they are used for purposes, in which they will get into close and long contact with the skin e.g. musical instruments or trinkets.

In Denmark the use of phthalates in toys and articles for small children is limited to a maximum concentration of 0.05% (w/w). This can be used as a restrictive comparison, as infants hardly suck at exotic wood articles to the same extent as at toys.

The demonstrated concentrations of phthalates are significantly below 0.05%.

For products, which might get into contact with food, the accepted maximum concentration varies depending of the type of phthalate and is between 1 and 60 mg/kg, corresponding to 1-60 μg/g (Fabech, 2003). It must, therefore, recommended that exotic wood articles (or other articles) if used for storage or in contact with food are not surface treated with other compounds than those appearing from the Positive List of the Danish Veterinary and Food Administration (BEK 111 af 20/2 03 om materialer og genstande bestemt til kontakt med fødevarer) (Statutory Order no. 111 of 20/2 2003 on materials and articles for contact with food).

6.4 Health Assessment of Elements

An overall health assessment of the demonstrated elements has been carried out. Compounds, the concentration of which is below the detection limit, have not been assessed. The assessments have been carried out as ingestion assessments, which is a restrictive method, as provisions thus are made for the use of the products i.e. food e.g. a salad bowl.

At assessment the monographs EHC (Environmental Health Criteria) and JECFA (Joint Expert Committee on Food Additives) (www.inchem.org). The different values for acceptable or tolerable intake is not directly comparable, as some have been determined as provisional or as maximum values, while others are not.

Boron (B): 801 ± 7 mg/kg: The estimated daily intake from food is 1.2 mg, from drinking water 0.2-0.6 mg/litre. The tolerable daily intake is 0.4 mg/kg body weight.

Cadmium (Cd): 0,128 ± 0,002 mg/kg: The estimated daily intake from food is 0.001-0.004 mg. A provisionally tolerable weekly intake of 7 mg/kg body weight has been determined.

Copper (Cu): 2,7; 9,9 mg/kg: The estimated daily intake from food is 2-5 mg. A provisional maximum tolerable intake is 0.05-0.5 mg/kg body weight.

Manganese (Mn): 21.3 ± 0.6 mg/kg: The estimated daily intake from food 2-9 mg, 10-50 microgram/day from drinking water1-10 mg/day is considered to be acceptable.

Lead (Pb): 1.25 ± 0.15 mg/kg: A provisional tolerable weekly intake of 50 mg/kg body weight has been laid down.

Zinc (Zn): 15.1 1.3 2 mg/kg: The estimated daily intake from the food is 8,8-14,4 mg. A tolerable intake of 0.3-1 mg/kg body weight has been laid down.

The only compound exceeding the limits for tolerable daily intake is boron. Taking the content into consideration it would be critical to use Hevea brasiliensis without surface treatment, if the wood has been treated with a boron containing fungicide.

6.4.1 Assessment of Risk of Allergic Reactions

When processing wood the exposure to wood dust could cause irritative, unspecified reactions from both skin and respiratory system.

Among the 5 Selected wood species ramin must be considered to be more skin and airway irritating than the other four ones.

Allergic reactions in airways can be seen at exposure to iroko and ramin.

Allergic contact eczema can especially be seen in contact with iroko and sheesham and, presumably to a less extent to ramin.

Considering the fact that we have only one product of Hevea brasiliensis, products made of this material do not seem to present risk to persons, who are allergic to natural rubber latex.

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Version 1.0 September 2005, © Danish Environmental Protection Agency