Clay is a natural product
Clay does not need any chemical additives and is therefore ideally suited for people suffering from allergies and those suffering from MCS
Loam consists of clay, sand and silt (this is something like fine dust, the grains of which are in the micrometer range). These three components in turn originated from a wide variety of mineral components that have been deposited over the course of many millennia, which is why clay can look so different. And in this state, clay, possibly even emaciated with sand and made pliable with water, is already ready to use for building. As a wall, ceiling, fill or plaster, it hardens through drying alone, since water is the only solvent required. It makes it very easy to work with. After drying, the clay is very firm and stable again. (Every now and then you find lumps of clay that are as hard as stone and cannot be crushed by hand, you have to use a hammer).
In the case of clay plaster, neither chemical setting (as with lime, for example) nor a material metamorphosis takes place. The use of synthetic additives that improve processability, accelerate drying or increase final strength is neither necessary nor sensible. Chemistry has no place in clay products.
In earth building there are building materials with a wide variety of organic or mineral additives, for example plant fibers for good insulation properties or as reinforcement. If these are left out by finding alternatives for reinforcement and insulation, and if the clay is used in its pure and pure form, its use is also safe for people who are allergic to those plants.