The U.S. Environmental Protection Agency on Friday released its long-awaited assessment of the toxic hazards of dioxins, a group of persistent contaminants emitted by chemical plants, waste incinerators, and other industrial facilities. While concluding that current exposure to dioxins “generally” does not pose a “significant health risk” over the course of a person’s lifetime, the EPA set a daily safe exposure rate of 0.7 picograms of dioxins per kilogram of body weight — a level that had been opposed by industry groups that contend it would stoke public concerns about food safety. Assistant EPA Administrator Paul Anastas called the assessment a “starting point” for future federal, state, and industry activities. The new standards could result in more stringent cleanup standards at contamination sites and stricter limits on allowed dioxin levels in water and air. Dioxins — which accumulate in animals and fish and can be consumed by humans — have been linked to problems with immune and reproductive systems, skin rashes, and liver damage.