my concern increased

[alpacinou]

I want to suggest that I have been concerned about something, but concerns increased.

How can I avoid the repetition of "concern" in this sentence?

I have always been concerned about the health of these animals and my concerns have grown in recent years.

 

[jutfrank]

There's no need to avoid the repetition there. However, I think you could transfigure it by creating greater cohesion between the two clauses by way of deictic reference, like this:

I have always been concerned about the health of these animals, and these concerns have grown in recent years.

Do you see how the noun phrase these concerns is in reference to the mention of the adjective concerned in the former clause? This reference turns the repetition into a cohesive device, which makes the sentence better. Remember that repetition is very often a strength, not a weakness.

 

[tedmc]

How about:

I have always been concerned about the health of these animals, (much) more so in recent years.