It looks fine to me. I know that plant as a Diffenbachia. If you touch the plant in any way wash your hands right away. It's common name is dumb cane, for a good reason. It will paralize your throat for a few minutes.

Smaller leaves usually mean it is needing more light. The variegation is not as pronounced on the smaller leaves also which also point to light issues. Move it to better light and see if that doesn't help the new leaves get larger.

This 'Camille' type of Dieffenbachia is a much smaller cultivar than the big ones. It can get tall over time, but can't make really big leaves. A chunky/porous/airy soil is necessary to keep them looking good & retaining leaves as long as possible. Otherwise the roots rot from being kept as moist as they need to be.

The irritating alkaloids that lead to this plant having been given the nickname dumbcane are in the sap inside the plant. Touching unbroken leaves and stems should be harmless. Very few plants are toxic by casual contact, (like poison ivy/sumac/oak.) IDK of any traditional house plants that are, except the mild irritation that can come from Juniper, sometimes kept as bonsai. MOST house plants (and landscape plants) have irritating alkaloids in their sap that can cause a skin reaction for the unfortunate few who are sensitive to them.

As far as getting plants in ones' mouth, unless they are known to be edible, they are toxic. Not all inedible plants will kill you or make everyone sick if they eat it. Plants are either edible or toxic (and some toxic plants have edible fruits, like tomato.) Any plant you don't know to be edible should be assumed toxic. Otherwise, it would be on a menu somewhere.

thank you for the replies

Al, Is that always true? I know about the long internodes, but with aroids, I find that the leaves should get larger as the plant matures. When they are suffering for light the leaves get smaller or stay in a juvenile form and never mature to their full potential, thus the question of whether or not a monstera is in fact a philodendron or a light deprived thing just hanging on until spring that comes up so often as of late.

"BTW - Low light levels produce long internodes and an increase in leaf size, as plants are programmed to maximize the photosynthesizing surface under these conditions."

"Is that always true?"

No, complete darkness produces small leaves. Some plants have zero distance between petioles as measured from the top of one petiole to the bottom of the petiole above it, e.g., bromeliads, banana plants, and nothing can change that. There are aroids that closely approach this situation, e.g., Colocasia Gigantea. But, petioles tend to lengthen in dim light. And, it may interest you to know that, unlike for the vast majority of other flowering plants, gibberellic acid (GA) doesn't have any morphological effect, such as internode lengthening, on many, if not all, aroids, except it causes blooming.

"As it continued to grow the leaves began to come in smaller than the biggest leaf that was on the plant when I originally purchased it."

The highest leaf in your picture is almost the biggest leaf on the plant therefore I think that you are exaggerating.

High humidity also tends to increase leaf size. Your plant was probably grown in a humid greenhouse before you bought it.

I am not exaggerating about the leaves. The "highest leaf when I bough it had a much bigger surface area and as the new higher leaves came in, they were much smaller.

Since you bought it, did the largest leaf die and fall off? I ask because I don't think I see it in the photo. And, I don't see progressively smaller leaves that would indicate poor growth conditions. Have the diameters of stem sections between petioles been getting successively smaller?

As I said before, leaves tend to be larger when grown in high humidity. I am guessing that the mechanism for that is that increased turgor pressure increases cell size rather than cell number.