A heavy metal that can bioaccumulate in the environment and is highly toxic if breathed or swallowed. The presence of excess methemoglobin in the blood, which replaces hemoglobin and results in loss of the ability to transport oxygen in the blood. A small amount of methemoglobin is present in the blood normally, but injury or toxic agents, such as nitrites, convert a larger proportion of hemoglobin into methemoglobin. One-millionth of a gram. Tiny living organisms that can be seen only with the aid of a microscope.
Some microorganisms can cause acute health problems when consumed in drinking water.
Also known as microbes. Standards established by EPA to protect human health and the environment from criteria pollutants, which apply for outside air throughout the nation. A group of toxic, persistent chemicals used in electrical transformers and capacitors for insulating purposes, and in gas pipeline systems as a lubricant. The sale and new use of PCBs were banned by law in 1979. Occurring, existing, or performed before birth.