Thank you Jakuvall!!

Ikea follows REACH guidelines which is the EU standard on the use of chemicals and I assume as they don't advertise it that their products don't qualify for LEEDS or GreenGuard Certification. Many composite board manufacturers follow ANSI standards which limit the amount of formaldehyde content (whether that is a higher or lower standard than the one achieved by Ikea I don't know) Ikea environmental statement: "Decreasing product emissions and formaldehyde use IKEA is concerned about product emissions and formaldehyde use. We have a long-term vision that emission levels in wood based products shall be at the same levels found in natural wood. For instance; we have investigated methods in order to replace formaldehyde in almost all glue applications. IKEA has decided on a new formaldehyde emission standard level, which will be implemented during 2008. The new emission standard means that we will decrease current limit levels by half in all wood based board. The new level will be comparable to half of E1 (the European Formaldehyde standard level, which is considered to not be hazardous to health)." Attached link indicates that paint finishes are much more effective at ceiling in emissions than other applied finishes but I don't know the science behind the statement. In part I think it is the complexity of the machining. I think even in wood to get square inside corners you need pass each routered edge separately (don't quote me). For those rounded edges the routered edge is probably done in one continuous pass (much quicker and cheaper). Here is a link that might be useful: info on sealing MDF

MDF - Medium Density Fiberboard Medium density fiberboard, or MDF, is a composite wood product similar to particleboard. It's made out of wood waste fibers glued together with resin, heat, and pressure. MDF is appropriate for many applications, from cabinetry to moulding, because it is smooth, uniform, and won't warp. MDF has many advantages over plank wood, particleboard, or high density fiberboard. It's very smooth because the wood fibers used in its manufacture are uniform and fine. This makes it have low "tear out," which means that when sawed, the end has a smooth cut instead of a jagged edge. This also means that a coat of primer and a couple of coats of paint take well, leaving an attractive, finished surface unlike other composite wood products. MDF also has a mild reaction to moisture, meaning it won't warp or swell in high-humidity applications like a bathroom cabinet. here are some old links http://www.thathomesite.com/forums/load/wood/msg0422465719842.html?7 http://www.thathomesite.com/forums/load/kitchbath/msg052132034578.html?16 http://ths.gardenweb.com/forums/load/kitchbath/msg11121915306.html

It sounds like they may be trying to educate you on the standard way they build cabinets, but it is possible to use all solid wood. Cost would most likely be affected though. Every pre-finished cabinet line I have worked with, high end or low, has a disclaimer form they require to be signed by the cabinet dealer and the customer stating that you understand the properties of a painted finish. It has to be sent in with the order or else the order wont be processed. No matter how well it is painted, tiny "cracks" in the paint will show at the seams between the stiles & rails of a paneled cabinet door. schreibdave noted the reasons above - expansion & contraction from humidity changes will get to you sooner or later. It does not look horrible, they are tiny hairline cracks that you would have to be ok with. Go to a showroom and take a look at the displays. Up close you will see them & notice that you had most likely not ever noticed them before. BUT...once you know about something, it may bother you. To answer your other questions, a mix or birch & mdf would not necessarily be bad. You would likely never know the difference once it was painted. It is probably a mix of cost, ease of construction & the paint / expansion qualities of the materials that determines what the cabinet maker uses. With that said - these are your cabinets, and you asked for low toxins/ VOC's. If your builder/ cabinet maker isn't working with you to assure you their methods and materials will fit your desires (or to find alternate ones that do), then I would find another professional that does. Surprisingly, factory finished cabinet lines can have a much better quality finish than "custom" built & painted on site cabinets. It is a controlled environment with less dust, etc. floating in the air. But good quality custom site built cabinets have their perks too. It all depends on the craftsman. Check out examples of their work similar to what you are looking for and see what you think. Good luck with your project!