In the last two decades, there’s been a national growth spurt in super-sized animal feedlots and slaughterhouses. That spurt has outpaced the ability of regulators to keep such places operating safely and cleanly — and that has led to polluted water bodies, food safety scares, and on-the-job injuries, according to a report released yesterday by the Sierra Club. The report found that during the 1980s and ’90s, corporate slaughterhouses produced 134 million pounds of tainted or possibly tainted meat; that millions of gallons of animal feces and urine seeped from waste pits into some 35,000 miles of rivers; that more than $48 million in fines were paid for health and environmental violations; and that worker-safety violations led to 13 deaths and more than $35 million in fines. The meat industry said the report rehashed old problems already addressed by local and federal regulators and failed to reflect improvements in recent years. But the Sierra Club called current environmental and safety standards inadequate, because they were devised to cover small family farms, not huge modern feedlots. The U.S. EPA is under court order to draft new feedlot regulations, which should be completed by the end of the year.