By 1990 everything classified was cross-cut and presumably treated from there after pickup. According to https://www.whitakerbrothers.com/pages/paper-shredders

By 1990 everything classified was cross-cut and presumably treated from there after pickup. According to https://www.whitakerbrothers.com/pages/paper-shredders-security-levels-reference-chart https://www.whitakerbrothers.com/pages/paper-shredders-secur... it was already up to p6-7, at least for everything I saw. There would always be signs posted warning against wearing a tie while using the shredder.