Brackets in the middle of a paragraph (News is current events)

[AllTheGoodNames.AreTaken]

I'm posting this in here because I only seem to see this in the news/media from reporters and news covers current events.

So I am wondering if there is anyone that can explain to me what brackets in the middle of a paragraph means??

I have this that I copied from an article:

"[While] inside the trench, the workers found sediment contaminated with toxic chemicals, including some so caustic that they disintegrated the shoelaces of one worker. The chemicals found at the site 'can be directly linked' to the Love Canal waste site, [a lawsuit] asserts."
Source: Newsweek Love Canal's Toxic Legacy

Why are there brackets around the word "While" and the words "a lawsuit" and what is with reporters placing brackets in random/needless places?

That would make perfect sense without the brackets. Another idea I had was to remove the words in brackets but if you do that it reads "The chemicals found at the site 'can be directly linked' to the Love Canal waste site, asserts." But now it REALLY doesn't make any sense. Who or what is making the assertions?

The only place I seem to come across this bracket issue is reading stories from news and media. What is the purpose of this? To confuse/distract people from the real point of the story?

[Autrevie]

The people on the Writer's forum could have helped you.

Brackets are used when quoting someone else and either removing the first word of the sentence or inserting words of your own in order to clarify the quote. It's necessary because they are only quoting a sentence or two of the original work.

Here's the paragraph from the original article. You can see how it needed changing in order to make sense in the newsweek article.

But while inside the trench, the workers found sediment contaminated with toxic chemicals, including some so caustic that they disintegrated the shoelaces of one worker. The chemicals found at the site “can be directly linked” to the Love Canal waste site, the Herrs’ suit asserts