Sealing cocobolo ... toxicity

Re: Sealing cocobolo ... toxicity

John K Jordan

Doc,

Everyone has an opinion, most based on what they've read or heard or experienced, largely anecdotal "evidence." My accumulated opinion is the dust is a big problem inhaled or on the skin. I work cocobolo and will get a rash if I leave the dust on my skin, so I protect against that. I have HEARD of people who get more serious reactions with even minimal exposure to dust.

However this is dust. Peoblems from contact with the wood itself appears to be rare and the reports are from people who wear wooden bracelets and watches held in contact with the skin for long periods. One company responds:

http://we-wood.us/pages/wood-allergy

This wood database page mentions some issues.

http://www.wood-database.com/wood-articles/wood-allergies-and-toxicity/

I personally wouldn't hesitate to use a cocobolo bookmark even unfinished but I cannot address the liability of selling them. What if a kid chews on one? Uses one as a tongue depressor? Falls asleep on one? But then, there are MANY woods besides cocobolo known to be toxic and some people may be allergic to them. (Walnut and red cedar are two common allergens) Should we start using plastic instead of wood? But then someone will be allergic to that. An interesting issue.

JKJ

My experience

Clint Searl

Severe reaction to cocobolo dust, but none to the solid wood.

Re: My experience

Barry L Elder

Been reading about exposure to rosewoods of various types and the general idea I've absorbed is that a wood allergy can likely be cumulative. That is, you can go years and years without a problem, and then Boom! there it is. Some people wind up in an Emergency Room because they are "tough"! Best to be careful and take care of yourself instead of the beautiful wood you are working on. SAFETY FIRST!

Re: Sealing cocobolo ... toxicity

robo hippy

Some one once said, "There are two kinds of wood turners, those who are allergic to cocobolo, and those who will become allergic to cocobolo." Continued exposure will reduce any one's resistance to it. Some are hyper sensitive to it, or become that way. Because of the oil contend in it, you either have to flood it with acetone or similar solvents before finishing, or use a carnuba paste wax type finish. The Doctor's Woodshop has a couple of building finishes for this type of wood. I have a couple of big chunks that are sitting, and haven't figured out if I am going to turn them, or put them up for auction. Last time I turned some, I thought I might have felt a slight irritation. Some woods already do that to me.

robo hippy

cocobolo finish

John K Jordan

>flood it with acetone or similar solvents before finishing, or use a carnuba paste wax type finish.

I usually use a shellac-based friction polish, Mylands. Most of the cocobolo I turn is in the form of small spindles or boxes and this works well. I've never tried using a solvent first. Since most of mine has come from the same two slabs my experience, though extensive, is limited. (interesting thought)

Once I tried using Watco oil on a piece. That was a mistake. In less than a year it was as black as ebony. Well, maybe that's an idea if I run out of ebony.

So far I'm OK with turning cocobolo when I wear a dust mask and long sleeves to keep the fine dust off my forearms. If I do get sensitized I suspect I can find someone to take it off my hands. At worse case, it burns very well.

I do have some big blocks and some pieces so heavy I can hardly lift them so I might make something big some day but I'm pretty happy making small things. A 50 lb slab can make a lot of finger tops...

JKJ

Some people are highly reactive

Geoff Whaling

My Mum is severely affected by many of our Australian Grevilleas including Southern Silky Oak (SSO - Grevillea robusta) and many of the garden ornamentals like "Robyn Gordon" - http://anpsa.org.au/APOL2009/mar09-s1.html

Any contact, even a brush against plant material in a garden or flowers in a floral arrangement, or with dust and fine wood shavings brings out a very irritating and quite painful dermatitis rash that alarmingly spreads quite quickly.

Curiously we have observed her handling items made from SSO that have been finished but she was unaware what the timber was. No reaction.

My thoughts are that if the finish is a film barrier then there is less chance of contact with the allergens pentadecylresorcinol and tridecylresorcinol.

Many years ago I was approached by a body piercing enthusiast to custom make a range of ear plugs for body stretching for him to sell to others from you guessed it Cocobolo & other exotic woods. I did my research and passed up what could have been a very good earner - BUT not worth the risk.

I believe that sensitivity to contact dermatitis can be triggered by cumulative exposure.

This is an interesting read about a contact allergy to cocobolo wood worn as a bracelet - http://www.medscape.com/viewarticle/516056_2 also a report of occupational exposure http://www.ncbi.nlm.nih.gov/pubmed/14749027

Perhaps book marks with a solid film finish are low risk but there is the distinct possibility that they could be handled for long periods of time by the reader.

I don't see much Cocobolo though I have a nice sample 2" square x 12" long piece sitting here along with a few other exotics waiting for me to play with them.

One thing we can be sure of is that we know very little about the chemical composition of many of our timbers. What gives them the unique aromatics, or the timber preservation characteristics, or pest resistance, or even the medicinal qualities known to many native peoples is slowly being discovered through research.

Medscape requires log-in

Ellis Walentine

Thanks for the information, Geoff. Maybe you could summarize the Medscape article for those of us who are not registered to access that site?

Cheers,

Ellis Walentine, Host

I didn't log in

Geoff Whaling

Ellis I don't have a log in either. I found the link with a Google search quite a while back & fortunately its still a live link. Google "Contact allergy to a cocobolo bracelet." will bring up an abstract on the US library MNIH and also Medscape. The Medscape article has images of the contact dermatitis injury.

"Abstract

Tropical woods are highly valued because of their strength, hardness, and resistance to moisture. These characteristics make them easy to work with and extremely durable, and that is why they have been used in the manufacture of wooden jewelry, musical instruments, furniture, and handles of many different objects. We present a case of a 44-year-old man who developed pruritus, erythema, and blistering around his right wrist, corresponding exactly to the area where he had worn a wooden bracelet. Thin-layer chromatography performed with the extract of the shavings revealed (R)-4-methoxydalbergione and obtusaquinone (the main components of cocobolo wood) and (S)-4'-hydroxy-4-methoxydalbergione (in lower amounts). Patch-testing with sawdust from the bracelet resulted in a very strong reaction. Patch tests with the pure constituents yielded +++ reactions to the main sensitizers of cocobolo, including obtusaquinone, but also to sensitizers present in other rosewoods. This last fact can be explained by cross-reactivity between different dalbergiones. Contact dermatitis from tropical woods is more frequent than thought, owing to their high sensitizing properties. An exhaustive search can identify the allergen responsible in many cases." from NMIH