This is the current release of the guideline.

Elemental mercury exposure

Note:

• This guideline addresses small spills and human exposures to elemental mercury. Exposures to organic mercury compounds (e.g., methylmercury) or inorganic mercuric salts (e.g., mercuric chloride) are not included.
• In addition, this guideline does not address chronic occupational exposure or large industrial releases of elemental mercury. It focuses primarily on small spills (typically less than 5 mL) that occur in a home or public area. It does not address aspiration or intravenous exposure to elemental mercury.

Evaluation
Management
Risk Assessment

Emergency Medicine
Family Practice
Internal Medicine
Obstetrics and Gynecology
Pediatrics

Advanced Practice Nurses
Allied Health Personnel
Emergency Medical Technicians/Paramedics
Nurses
Pharmacists
Physicians

To assist poison center personnel in the appropriate out-of-hospital triage and initial out-of-hospital management of patients with suspected exposures to small amounts of elemental mercury by:

• Describing the process by which a specialist in poison information should evaluate an exposure to elemental mercury
• Identifying the key decision elements in managing cases of elemental mercury exposure
• Providing clear and practical recommendations that reflect the current state of knowledge
• Identifying needs for research

Children and adults including pregnant women with suspected exposure to elemental mercury

Evaluation

1. Assessment of key decision elements for triage
   • Patient intent
   • Route of exposure
   • Presence of symptoms
   • Time of onset of toxicity
   • Whether there was intentional heating of elemental mercury

Management

1. Referral to an emergency department
2. Home observation or non-urgent outpatient evaluation
3. Referral for evaluation of surgical removal of mercury injected into soft tissue
4. Decontamination including removing jewelry and washing the affected area with mild soap and water, removing contaminated clothing and placing it in a sealed plastic double-bag for proper disposal
5. Evaluation by obstetrician or primary care provider for asymptomatic pregnant women
6. Proper clean-up according to Environmental Protection Agency (EPA) guidelines
7. Consulting local authorities for proper disposal of contaminated items

Note: Emesis induction and administration of activated charcoal were considered but not recommended.

• Mortality
• Signs and symptoms of toxicity
• Environmental risk factors for elemental mercury poisoning

Hand-searches of Published Literature (Primary Sources)
Hand-searches of Published Literature (Secondary Sources)
Searches of Electronic Databases

Search Strategy

A single investigator performed literature searches for relevant articles. The National Library of Medicine's PubMed database was searched (through May 2006) using elemental mercury poisoning as a Medical Subject Headings (MeSH) term, limited to humans. The PubMed database was further searched using mercury as a textword (title, abstract, MeSH term, CAS registry) plus either poison* or overdos* or intox*, or toxic* limited to humans. This process was repeated in International Pharmaceutical Abstracts (1970–May 2006, excluding abstracts of meeting presentations), Science Citation Index (1977–May 2006), Database of Abstracts of Reviews of Effects (accessed May 2006), Cochrane Database of Systematic Reviews (accessed May 2006), and Cochrane Central Register of Controlled Trials (accessed May 2006). Reactions (1980–May 2006), the elemental mercury poisoning management in Poisindex, and the bibliographies of recovered articles were reviewed to identify previously undiscovered articles. Furthermore, North American Congress of Clinical Toxicology (NACCT) abstracts published in the Journal of Toxicology Clinical Toxicology (1995–2004) and Clinical Toxicology (2005) were reviewed for original human data.

Five major toxicology textbooks were reviewed for recommendations on the management of elemental mercury poisoning and for citations of additional articles with original human data in the chapter bibliographies. The Toxic Exposure Surveillance System (TESS) maintained by the American Association of Poison Control Centers was searched for deaths resulting from unintentional elemental mercury poisoning. These cases were abstracted for review by panel members. All US poison control centers were surveyed in 2006 to ascertain their out-of-hospital management and triage practices for elemental mercury poisonings.

Criteria Used to Identify Applicable Studies

The recovered citations were entered into an EndNote library and duplicate entries were eliminated. The abstracts of these articles were reviewed, searching specifically for those that dealt with estimations of doses with or without subsequent signs or symptoms of toxicity and management techniques that might be suitable for out-of-hospital use (e.g., gastrointestinal decontamination). Articles that did not meet either of the preceding criteria, did not add new data (e.g., some reviews, editorials), or that exclusively described inpatient-only procedures (e.g., dialysis) were excluded.

Not stated

Weighting According to a Rating Scheme (Scheme Given)

Systematic Review with Evidence Tables

Expert Consensus (Delphi)

An expert consensus panel was established to develop the guideline (see Appendix 1 of the original guideline document). The American Association of Poison Control Centers (AAPCC), the American Academy of Clinical Toxicology (AACT), and the American College of Medical Toxicology (ACMT) appointed members of their organizations to serve as panel members. To serve on the expert consensus panel, an individual had to have an exceptional record in clinical care and scientific research in toxicology, board certification as a clinical or medical toxicologist, significant US poison control center experience, and be an opinion leader with broad esteem. Two specialists in poison information were included as full panel members to provide the viewpoint of the end-users of the guideline.

Guideline Writing and Review

The lead author prepared a draft guideline. The draft was submitted to the expert consensus panel for comment. Using a modified Delphi process, comments from the expert consensus panel members were collected, copied into a table of comments, and submitted to the lead author for response. The lead author responded to each comment in the table and, when appropriate, the guideline draft was modified to incorporate changes suggested by the panel. The panel again reviewed the revised guideline draft and, if there was no strong objection by any panelist to any of the changes made by the lead author, the draft was prepared for the external review process.

The rating scheme for the strength of the recommendation (A-D, Z) is directly tied to the level of evidence supporting the recommendation.

A formal cost analysis was not performed and published cost analyses were not reviewed.

External Peer Review
Internal Peer Review

External review of the second draft was conducted by distributing it electronically to American Association of Poison Control Centers (AAPCC), American Academy of Clinical Toxicology (AACT), and American College of Medical Toxicology (ACMT) members and the secondary review panel. The secondary review panel consisted of representatives from the federal government, public health, emergency services, pediatrics, pharmacy practice, and consumer organizations (see Appendix 3 of the original guideline document). Comments were submitted via a discussion thread on the AAPCC web site or privately through e-mail communication to AAPCC staff. All submitted comments were rendered anonymous, copied into a table of comments, and reviewed by the expert consensus panel and the lead author. The lead author responded to each comment in the table and his responses and subsequent changes in the guideline were reviewed and accepted by the panel.

An algorithm is provided in Appendix 4 of the original guideline document for triage for elemental mercury exposure.

The type of supporting evidence is identified and graded for each recommendation (see "Major Recommendations").

Appropriate out-of-hospital triage and initial management of patients with suspected elemental mercury exposure

Not stated

• This guideline was developed for the conditions prevalent in the United States. While the toxicity of elemental mercury is not expected to vary in a clinically significant manner in other nations, the out-of-hospital conditions could be much different. Do not extrapolate this guideline to other settings unless it has been determined that the conditions assumed in this guideline are present.
• This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment.

Limitations of the Literature

The elemental mercury literature suffered from many potential limitations that could affect the interpretation of the data for this guideline. Most of the data were retrospective and estimates of spill or exposure amount, exposure duration, and the nature or onset of symptoms were usually based on patient or family recall, often several weeks or months after the exposure originally occurred. Exposure might have occurred by more than one route (e.g. dermal, ingestion, inhalational) in a given individual, but the extent to which each occurred was generally not reported or might not have been known. The local environmental conditions (e.g., location, temperature, ventilation, vacuuming, heating) were not often reported with inhalational exposures. Many of these factors can have a critical impact on the amount of mercury inhaled and resulting toxicity.

Air mercury measurements can help circumvent some of the limitations in using quantitative assessments of exposure amounts. However, they have their own limitations as potential estimates of cumulative or peak exposure. Air measurements represent only one point in time and space and can fluctuate depending on a number of factors (e.g., higher concentrations generally associated with higher temperatures, poorer ventilation, and vacuuming). Thus, their interpretation depends on environmental context, which was often not reported. In many instances, it was not clear when the airborne mercury measurements were made in relation to the spill/exposure, where in spatial proximity to the exposure the air samples were obtained, or whether samples were taken at the breathing space or surface level. Breathing space concentrations are typically much lower than corresponding measurements taken directly above an elemental mercury spill or contaminated object. In addition, abatement measurements were frequently performed after peak exposure and might have underestimated the actual concentration at the time of exposure. In some cases, air mercury concentrations were reported but not exposure amounts or vice versa.

Individuals can differ in their responses to similar exposures because of inter-individual differences in minute ventilation, toxicokinetics, or toxicodynamics. Such potential differences make comparing the data between patients, or extrapolating it to the broader population, difficult. The symptoms of mild mercury poisoning are nonspecific and its diagnosis might be under-reported in the literature. Urine and blood mercury concentrations are limited in their ability to confirm or rule out a significant exposure. Depending on the circumstances (e.g., the acuity of exposure, timing of measurements, laboratory performance), urine or blood concentrations might not reflect the actual exposure. In some cases, background occupational exposure might have been present and could have contributed to a patient's reported symptoms or biological mercury measurements.

In cases describing mercury spills from broken thermometers, the thermometer size or volume of mercury was generally not reported. Different thermometers contain different amounts of mercury.

In the few large cases series included in the evidence table, elemental mercury exposure amounts, air concentrations, and frequency or severity of subsequent effects were often reported as a ranges, percentages or mean values, so that individual doses resulting in specific effects could not be distinguished.

In several instances, the quality of data might have been lower than implied by the level of evidence score. For example, an article classified as level 2b could have been a cohort analysis of the relationship between urine mercury concentrations and symptom severity, but the quality of data relating to the more pertinent relationship of exposure amount or air level vs. symptom severity might have been only a level 4. Most studies reviewed were not designed to specifically assess a toxic exposure threshold (i.e., the relationship between air concentration or spill amount and clinical effects), yet this was a primary question that the guideline panel sought to answer from the review of the literature.

The number of articles reporting gastrointestinal or subcutaneous exposures was limited. This could be the result of the infrequency of such exposures, an inherent lack of toxicity by these routes, poor recognition of such cases, or simply a lack of reporting. It was difficult to draw robust conclusions from this data.

An implementation strategy was not provided.

Getting Better

Effectiveness
Timeliness

Not applicable: The guideline was not adapted from another source.

2007 Apr 9

American Association of Poison Control Centers - Professional Association

Health Resources and Services Administration, U.S. Department of Health and Human Services

Not stated

Primary Authors: E. Martin Caravati, MD, MPH; Andrew R. Erdman, MD; Gwenn Christianson, MSN; Lewis S. Nelson, MD; Alan D. Woolf, MD, MPH; Lisa L. Booze, PharmD; Daniel J. Cobaugh, PharmD; Peter A. Chyka, PharmD; Elizabeth J. Scharman, PharmD; Anthony S. Manoguerra, PharmD; William G. Troutman, PharmD

Expert Consensus Panel Members: Lisa L. Booze, PharmD, Certified Specialist in Poison Information, Maryland Poison Center, University of Maryland School of Pharmacy, Baltimore, Maryland; E. Martin Caravati, MD, MPH, FACMT, FACEP, Professor of Surgery (Emergency Medicine) University of Utah, Medical Director, Utah Poison Control Center, Salt Lake City, Utah; Gwenn Christianson, RN, MSN, Certified Specialist in Poison Information, Indiana Poison Center, Indianapolis, Indiana; Peter A. Chyka, PharmD, DABAT, FAACT, Professor, Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Knoxville, Tennessee; Daniel J. Cobaugh, PharmD, FAACT, DABAT, Director of Research, ASHP Research and Education Foundation, Bethesda, Maryland, Former Associate Director, American Association of Poison Control Centers; Daniel C. Keyes, MD, MPH, Medical Director, Pine Bluff Chemical Demilitarization Facility, Associate Professor, Southwestern Toxicology Training Program, Dallas, Texas; Anthony S. Manoguerra, PharmD, DABAT, FAACT, Professor of Clinical Pharmacy and Associate Dean, School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, Former Director, California Poison Control System, San Diego Division, San Diego, California; Lewis S. Nelson, MD, FACEP, FACMT, FACCT, Associate Professor of Emergency Medicine, New York University School of Medicine, Associate Medical Director, New York City Poison Control Center, New York, New York; Elizabeth J. Scharman, PharmD, DABAT, BCPS, FAACT, Director, West Virginia Poison Center, Professor, West Virginia University School of Pharmacy, Dept. Clinical Pharmacy, Charleston, West Virginia; Paul M. Wax, MD, FACMT, Attending Toxicologist, University of Texas Southwestern Medical Center, Dallas, Texas; Alan D. Woolf, MD, MPH, FACMT, Director, Program in Environmental Medicine, Children's Hospital, Boston, Associate Professor of Pediatrics, Harvard Medical School, Boston, Massachusetts

There are no potential conflicts of interest reported by the expert consensus panel or project staff regarding this guideline.

This is the current release of the guideline.

None available

None available

This NGC summary was completed by ECRI Institute on December 17, 2007. The information was verified by the guideline developer on January 14, 2008.

This NGC summary is based on the original guideline, which is subject to the guideline developer's copyright restrictions.