News - Public Health Concern - Low Level Mercury

Low Level Mercury

Mercury is one of the top ten chemicals that have become a major public health concern.  Although mercury exists in nature in soil, water, and air, the increasing presence of mercury in the environment is mainly caused by human activity.  Typically, since the industrial revolution, the release of mercury into the environment is exponentially increased through coal fired power generation plants, residential heating and cooking using coal, mining, and waste incinerating, as well as the other industrial processes.   Mercury may have toxic effects on the nervous, digestive, and immune systems; on the lungs, kidneys, skin and eyes.  Exposure to mercury even with small amounts may cause serious health problems and is a threat to child development in-utero and in early stages of life.  A well-known example of mercury's toxic effects on public health is an incident reported in Minamata, Japan where 50,000 people were affected to some extent, while in the most severe cases people suffered brain damage, paralysis, incoherent speech, and delirium.  The investigation found the mercury pollution there was caused by waste water discharge from a factory that produced acetic acid.

Once in the environment, mercury can be converted by bacteria to methyl mercury which can bio-accumulate in fish or shellfish.  Because of this, the amount of mercury can magnify in the body of large predatory fish through eating mercury containing smaller fish who acquire mercury through ingestion of mercury contaminated plankton.   Once methyl mercury is ingested in the human body, more than 90% is absorbed into the blood from the gastrointestinal tract.  It then can cross the blood-brain barrier and accumulates in the tissue of any organ.

People may be exposed to mercury in any of its forms and in different circumstances.  However, eating mercury contaminated fish is a primary cause of mercury exposure presently.  As a result, people who rely on subsistence fishing and people who consume a lot of fish in their diet are one of two groups of people that are more susceptible to the effects of mercury poisoning. The other group of people who are more sensitive to the effects of mercury are fetuses during their development.  Mercury can adversely affect the growth of brain and nervous system of a baby which can result in the impairment of his/her cognitive thinking, memory, language, fine motor and visual spatial skills.

Because mercury is ubiquitous in our environment, it poses a real challenge to maintain a clean environment.  As a result, a lot of states' permits increasingly require compliance to a lower water effluent limit for mercury.  The low-level mercury method provides an ability to assess compliance with mercury water quality standards below 0.2 ug/L.  Additionally, in accordance with the Clean Water Act (CWA), the permit requires the surface water discharge to be analyzed using a sufficiently sensitive method so that reasonable assurance can be provided to prevent the future will be not violated.  CWA also requires NPDES (National Pollutant Discharge Elimination System) permits to include effluent limitations that are as stringent as necessary to meet water quality standards.  Over the past few years, we have seen more and more of our clients switch to low level mercury testing from traditional high-level mercury analysis.

Ana-Lab adopted EPA Method 245.7 for analysis of low level mercury with a detection limit of 0.6 ng/L, which is close to the minimum quantization limit of EPA Method 1631E (0.5 ng/L). As a result, our low-level mercury analysis will satisfy the requirements for EPA 1631E.

When using low-level mercury analysis, clean sample handling techniques should be applied to sample collection to preclude the sample contamination.  It is also recommended to collect at least one blank at each site when the sample is collected. The blank may either be an equipment blank or a field blank. Field blanks should be collected only if no equipment other than the sample container is used to collect samples.  If the sampling procedure involves using additional equipment, such as a pump and pump tubing, an equipment blank should be collected.

For additional information about sample collection, bottle requirements, and analysis, please do not hesitate to contact us so that we may assist you.


Bill Peery

Bill Peery is the Vice President of Technical Services and has been with Ana-Lab for over 30 years. He holds a Bachelor of Arts degree in Biology and Chemistry from the University of Texas at Austin and a Bachelor of Science degree in Software Engineering from Lamar University. He also earned his Master's degree in Computer Science and Chemistry from the University of Texas at Tyler.