Survey of Chemical Substances in Consumer Products, 64 – Emission of chemical substances from products made of exotic wood

Emission of chemical substances from products made of exotic wood

7 Concluding Discussion

7.1 Compounds found in the Emission
7.2 Compounds found by Migration into artificial saliva
7.3 Risk of Allergic Reactions
7.4 Future Examinations

7.1 Compounds found in the Emission

For the examined products made of exotic wood (with or without surface treatment) only minor amounts of chemical compounds were found in the emission at the climate chamber measurements.

Totally 25 individual compounds were demonstrated at the climate chamber measurements, out of which more of the individual compounds could be identified in more of the products. There is every probability that a part of these compounds origins from the surface treatments of the products in question.

For only very few compounds in the emissions from the wood species examined the health effects of the compounds (cancer, allergy, congenital malformation and nervous system effects and other effects) became of importance in relation to the determination of the LCI-value.

The examined products have been assessed in relation to health by determining the S-value on basis of LCI-values and on basis of comfort considerations of the indoor-relevant time-value.

The S-values vary the 3-days measurements 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. 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.

By the measurements on day 28 the values had dropped further. At that time the S-value for all products - rubber tree, too – was below 1 (An S-value below 1 is considered to be unproblematic).

The stated measurements thus show a picture indicating that emission of individual compounds from the examined exotic wood species or their surface treatments only to a very limited extend takes place. The obtained S-values and indoor-relevant time-values are based on a material loading, which for most of the products would be an absolute "worst case". Nevertheless, none of the products would at the scenario stated imply health effects.

Rubber tree is the only examined product, which has an S-value, which during the measuring period exceeds 1. The individual compounds important in relation to the calculated S-value are formaldehyde and acrolein. It is less plausible that they are constituents of the rubber tree itself. There is on the contrary every probability that they origin from the surface treatment.

The results of the examination thereby shows that the examined untreated exotic wood species have the same low emission as the untreated wood species oak, beech, and ash, which were examined in Environmental Project no. 501 (The Danish Environmental Protection Agency, 1999).

The problems in question with emission from rubber tree could be solved by changing the surface treatment or by leaving the product to emit unpacked for 1 month, before release to the consumers.

The emission of chemical compounds from the products has been very low. An explanation to this could be that exotic wood species are imported from geographical area, in which the relative humidity frequently is much higher than is the case in Denmark. By a drying process a major part of the compounds is expected to emit. At the same time some of the surface treatments will contribute to encapsulate the compounds in the wood and thereby limit the emission.

7.2 Compounds found by Migration into artificial saliva

None of the compounds found occur in concentrations that exceed the calculated TDI-values. In return compounds occur in both products, which are listed on the list of the Danish Working Environment Service for allergy and sensitising compounds including vanillin and phtalacidanhydride.

It is generally assessed that it is inappropriate that allergen compounds from the products in question are emitted, it is also inappropriate that phthalates such as phtalacid monobutyl ester and diethylphtalate are emitted from the products. The problem is of most importance in case the products are used for storage of food (salad bowls, chopping boards etc.) or if they are used for purposes, in which they get in close and long contact with the skin e.g. musical instruments or trinkets.

It is, therefore, generally suggested that exotic wood products (or other products), which have not been surface treated with other compounds than those appearing from the positive list of the Ministry of the Food, Agriculture and Fisheries, if they are used for storage of food or in close contact like e.g. chopping boards and kitchen table tops. At the same time it must be recommended that rubber tree is not used without surface treatment, if the wood has been treated with boron fungicides. It will most probably be hard to obtain complete information about the products, which at the place of origin have been used as fungicide.

It should be noted that the results presented in the report solely concern the products examined and they should only be considered as based on random samplings. The results obtained are, therefore, not representative for the respective wood species or for exotic wood in full.

7.3 Risk of Allergic Reactions

Processing of wood can imply exposure to wood dust, which may cause irritative, unspecified reactions from skin and airways.

Among the 5 examined wood species ramin should be considered to be more skin and respiratory irritation than the other 4. Allergic reactions in airways can be seen by exposure to iroko and ramin. Allergic contact eczema can especially be seen from iroko and sheesham, and, probably to a less extent from ramin.

Considering the fact that we have only examined one product made of rubber tree, products made of this type do not seem to present a risk to persons, which are allergic to natural rubber latex.

7.4 Future Examinations

In this project 10 Selected products have been examined for the emission of chemical compounds, out of which only 5 have been subjected to a quantitative analysis of the emission in climate chamber. The project, therefore, only gives limited information about the emission of chemical compounds from consumer products made of exotic wood.

The project, however, demonstrated that it on basis of the examined wood species/products could be interesting to carry out further examinations of products made of rubber tree (Hevea brasiliensis) – especially when the wood species is used for toys or products getting in contact with food. This requirement is based on the results of the project concerning compounds found in the wood itself and compounds emitted from the surface by migration.

A lot of exotic wood species exist, which have not been treated in this project and which widely are used in the residences. We find that it could be interesting to analyse these wood species in a similar project.

By future analyses it is essential to test both untreated wood and wood with a surface treatment.