Report period

Well, the negative items remain on the credit reports from 7 to 10 years.

7 - 7 1/2 years from the date of last activity on the account. It's pretty easy, however, to dispute a CA's reporting on your account. 90% of time, they can't validate the debt and have to remove it.

How do we dispute CA's report?

Write a letter to each of the credit bureaus (on which the incorrect report appears) and tell them that you dispute the report and would like an investigation.

Seven years from last activity on the account has not been the law since 1996, with the amendment of the FCRA by the addition of section 605(c).
Collections remain in your CR for up to 7 years plus 180-days from the date of first delinquency on the associated OC account. FCRA 605(c).

Disputes under the FCRA are based on the accuracy of items of information reported by any party to your CR. When you dispute with a debt collector, the items of information they report, if any, primarily include the name of the OC, the amount of the debt under collection, the date of referral to them for collection, the dates and amounts of any payments made to them, and in some instances, the DOFD.
Matters covered under the FDCPA, such as disputes relating to their collection activities, such as their compliance with the DV process, are not reported to a CRA, and are thus not disputable under the FCRA.
So, disputing with a debt collector depends upon what you are disputing, and your documentation of how their reporting to the CRA was inaccurate.

I am referring to third party collection agencies. Under FCRA, they CANNOT enter a negative trade line on the credit report unless they can validate the account. My point is that 90% of the time these are JDBs who have no documentation of the debt and have no business putting it on someone's credit report. If you dispute it, it will be removed.

Third-party collection agencies are debt collectors.
There is no provision of the FCRA that prevents a debt collector from reporting to a CRA without first validating the debt. Debt validation is a collection practice provision under the FDCPA, and is not a credit reporting statute. Failure to validate does not compel deletion of their reporting from your CR. It only requries the cessation of continued collection activities.
A debt collector can first report to your CR, even prior to any communication with you, or sending you a collection (dunning) notice. Posting to your CR is considered an intitial communication with the consumer, and thus triggers their requirement under FDCPA 809(a) to then provide you dunning notice within 5-days thereafter.
A debt collector can send you dunning notice, and then report to the CRA up to such time as they receive your DV letter.
Neither of those conditions require any prior debt validation before they can report to a CRA. And violation of either of those FDCPA provisions does not compel CR deletion.They are not items of information reported to a CRA, and are thus not covered by the dispute processes under the FCRA.
To compel deletion of reporting of a collection, you would have to file a dispute under the FCRA that establishes, with supporting documentation, that the basis for their reporting itself, i.e., the existence of any debt, was inaccurate, and thus the reporting of a CA was inaccurate.

Can it not be argued that reporting the debt on one's credit report is, in fact, a "collection effort"? I think it is. If the report can be construed as an "initial contact to attempt collection" then, it's a collection effort, no? Therefore, I think that, if you're requesting validation and all collection efforts are to be stopped during that process, then the trade line should be removed until the debt is validated.

You are correct, up to a point. Yes, reporting to a CRA is considered an action on the collection of a debt, and is barred after receipt of a timely DV letter until validation is provided. However, the collection bar of FDCPA 809(b) applies to further collection activities, and not to reporting previously done.
It is perfectly permissible for a debt collector to report to a CRA, even prior to sending a collection (dunning) notice. Their credit reporting is then considered an initial communication wth the consumer, triggering their requirement to send a dunning notice within 5-days thereafter. They can then even continue credit reporting up to the time they receive a timely DV letter. Receipt of the DV letter does not make their prior reporting inaccurate, or a violation of FDCPA 809(b).