# Inorganic Mercury

TEACH Chemical Summary Inorganic mercury is one of three forms of mercury listed in TEACH. In addition to this Chemical Summary, there are separate Chem ical Summaries for organic mercury (e.g., methylmercury) and for elemental mercury.

U.S. EPA, Toxicity and Exposure A ssessment for Children’s Health This TEACH Chemical Summary is a compilation of information deri ved primarily from U.S. EPA and ATSDR resources, and the TEACH Database. The TEACH Database contains summaries of research studies pertaining to developmental exposure and/or health effects for each chemical or chemical group. TEACH does not perform any evaluation of the validity or quality of these research studies. Research studies that are specific for adults are not included in the TEACH Database, and typically are not described in the TEACH Chemical Summary.



### I. INTRODUCTION

Mercury in elemental form is a silver-colored metal that exists as a thick liquid at room temperature, familiar to most people as the silver liquid insi de mercury thermometers. Mercury can chemically combine with other elements to form organic (car bon-containing) and inorgani c (not containing carbon) compounds. Mercury is a naturally-occurring metal that is used in man-made pr oducts and processes, and is emitted into air from industrial sources (1-3). Human exposure to mercury occurs from a variety of sources, e.g., breathing mercury-cont aining air, using commercial pr oducts that contain mercury, and ingesting some types of fish that contain methylmercury (1, 2, 4, 5). The U.S. EPA provides a Web site with information about mercury expos ure and effects, with a portal at www.epa.gov/mercury (6).

There are three major types of mercury, each of wh ich is covered in a separate TEACH Chemical Summary: 1) elemental mercury, fo und in thermometers, fluorescent bul bs, dental amalgam fillings, and other sources; 2) organic mercury, predominantly methylmercury, found in foods such as fish, and ethylmercury found in some vaccine preservatives a nd some antiseptics; and 3) non-elemental forms of inorganic mercury, found primarily in batteries, some disinfectants, and some health remedies and creams (1, 2, 5). This Chemical Summary focuses on non-elemental inorganic mercury; additional information on elemental and organic mercury is available in sepa rate Chemical Summaries on this U.S. EPA TEACH
Web site.

Inorganic mercury describes a category of mercury co mpounds that includes mercuric chloride, mercuric acetate, mercuric sulfide, and other compounds. Of th e inorganic mercury compounds, mercuric chloride is more common than other compounds. Mercuric chloride is a white powder that is soluble in water (1-3, 5). Exposure of children to inorgani c mercury above levels of concer n is uncommon, and most likely to occur following ingestion of items containing inorganic mercury, such as some batteries; or use of some homeopathic remedies or skin bleaching creams (1, 3, 7-11).

Mercuric chloride exposure can be toxic to the kidney, stomach, and inte stines; and can lead to increased blood pressure (1, 12). Experimental animal studies have shown embryot oxic effects, including increased rates of miscarriage and stillbirths, following merc uric acetate exposure (13-15) or mercuric chloride exposure (16-19) during pregnancy. Au toimmune kidney damage has also been reported in adult rats following mercuric chloride exposure (1).

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 1Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 2 

### II. EXPOSURE MEDIA AND POTENTIA L FOR CHILDREN’S EXPOSURE 1

Exposure Media Relative Potential for Children’s Exposure 2,3 Basis 4

CommerciallyAvailable Personal
Care Products Medium Inorganic mercury can be found as a constituent in some imported cosmetic skin-bleaching creams and herbal
remedies. Mercuric chloride is also found in some batteries.

Medical/Medicinal
and Home
Remedies Lower Inorganic mercury may found at elevated levels in some
medicinal and home remedies.
See the Organic Mercury Chemical Summary for information about ethylmercury from some vaccine uses.

Indoor Air Lower Inorganic mercury is not generally found at elevated levels in indoor air. Indoor air may contai n higher levels of inorganic mercury, e.g., in homes of industrial workers who work in chlor-alkali plants after worker s wear clothes home from the workplace that are contaminat ed with inorganic mercury.
See the Elemental Mercury Chemical Summary for information about mercury exposure in indoor air from elemental mercury spills, such as from mercury-containing thermometer or equipment breakage.
Diet Lower Inorganic mercury is not generally found in foods.
See the Organic Mercury Chemical Summary for information about methylmercury exposure from diet, particularly eating fish.
Ambient Air Lower Inorganic mercury is not generally found at elevated levels in
ambient air. Drinking Water Lower Inorganic mercury is not generally found at elevated levels in drinking water.

Sediment Lower Inorganic mercury is not generally found at elevated levels in
sediment.

Soil Lower Inorganic mercury is not generally found at elevated levels in
soil.

Surface Water Lower Inorganic mercury is not generally found at elevated levels in
surface water.

1 For more information about child-specific exposure fact ors, please refer to the Child -Specific Exposure Factors Handbook ( http://cfpub.epa.gov/ncea/cfm/r ecordisplay.cfm?deid=55145 ).

2 The Relative Potential for Children’s Exposure category refl ects a judgment by the TEACH Workgroup, U.S. EPA, thatincorporates potential exposure pathways, frequency of exposure, level of exposure, and current state of knowledge. Sitespecific conditions may vary and influence the relative potential for exposure. For more information on how these determinations were made, go to http://www.epa.gov /teach/teachprotocols_chemsumm.html

. 3 Childhood represents a lifestage rather than a subpopulation, the distinction being that a subpopulation refers to a portion of the population, whereas a lifestage is inclusive of the entire population.

4 Information described in this column was derived from several resources (e.g., 1-5) including studies listed in the TEACH Database ( http://www.epa.gov/teach ).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 3 

### III. TOXICITY SUMMARY 5, 6

Mercury is a neurotoxicant, and ma y affect many areas of the brain ( 1, 2, 12). Different forms of mercury may not all have neurotoxic effects listed here, a nd many neurotoxic effects of mercury exposure have been attributed to methylmercury exposure (s ee TEACH Organic Mercury Chemical Summary). Reported neurotoxic symptoms of me rcury exposure include poor perfor mance on neurobehavioral tests, of attention, fine motor function, la nguage, visual-spatial abilities (e.g., drawing), and verbal memory (1, 2, 12). Exposure to mercury during pregnancy and de velopment may impact neurological and cognitive development of children (see TEACH Organi c Mercury Chemical Summary) (20, 21).

Children and adults exposed to mercury, including i norganic mercury, have been reported to develop a disorder called acrodynia, or “pink disease” (1, 12). Symptoms include leg cramps; irritability; and redness and peeling of the skin of hands, nose, and soles of the feet. Itching, fever, sweating, salivating, rashes (including “baboon syndrome” rashes in the buttocks, anal, a nd genital regions), sleeplessness, and/or weakness have also been reported (1). Additio nal reported effects of i norganic mercury exposure in children and adults include kidney damage and dige stive tract problems includi ng diarrhea, nausea, and ulcers (1, 12). Increased bl ood pressure and decreased heart rate vari ability in children exposed to mercury has been reported (1, 12, 22-24). Neurological eff ects including twitching, tic s (uncontrollable muscle movements), and impaired gait have been reported in adults and children follo wing exposure to mercuric chloride (1, 9, 12, 25). There are limi ted reports of death in adults following ingestion of mercuric chloride at doses of 10-42 mg mercury per kg body wei ght with cardiovascular fa ilure, gastrointestinal damage, and acute renal failure (10).

In experimental animal studies, merc uric acetate or mercuric chloride exposure during development led to embryotoxicity (increased fetal deaths, and increase d occurrence of fetal abnormalities such as retarded growth and exencephaly, or exposed brain tissue) in hamsters and mice (13-19, 26). Following mercuric chloride exposure, neonatal rats e xhibited altered rates of organ grow th for several organs (e.g., liver, brain, heart), and altered levels of several neurotrans mitters in the brain (27); in adult rats exposure resulted in hair loss, weight loss, and immune-media ted kidney damage in adult rats (1). Following acute exposure to mercuric chloride (>0.46 mg/kg/day), adult rats experienced acute renal failure attributed to tubular and glomerul ar pathology (12).

Carcinogenicity Weight-of-Evidence Classification 7 : Mercuric chloride was cl assified by U.S. EPA in 1994 as a possible human carcinogen based upon an absence of data in humans and limited evidence of carcinogenicity in rats (observed renal t ubular cell tumors in adult rats) (1) ( www.epa.gov/iris/subst/0692.htm , II.A.1). The World Health Organi zation International Agency for Research on Cancer (IARC) in 1997 classified inorga nic mercury compounds as Group 3, “not classifiable as to their carcinogenicity in humans,” with insu fficient evidence for carcinogenicity in humans, and limited evidence for carcinogenic ity of mercuric chloride in experimental animals ( http://monographs.iarc.fr/E NG/Monographs/vol58/volume58.pdf ).

5 Please refer to research article summaries listed in the TE ACH Database for details about study design considerations (e.g., dose, sample size, exposure measurements).

6 This toxicity summary is likel y to include information from workplace or other studies of mature (adult) humans or experimental animals if child-specific information is lacking for the chemical of interest. Summaries of articles focusing sole ly
on adults are not listed in the TEACH Database because the TEA CH Database contains summaries of articles pertaining to developing organisms.

7 For recent information pertaining to carcinogen risk assessment during development, consult A Guidelines for Carcinogen Risk Assessment and Supplemental Guid ance on Risks from Early Life Exposure @ at http://www.epa.gov/cancerguidelines

.Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 4 

### IV. EXPOSURE AND TOXICITY ST UDIES FROM THE TEACH DATABASE

This section provides a brief description of human and animal studies listed in the TEACH Database. For more details about study design parameters, e.g., doses and ex posure information, please refer to article summaries in the TEACH Database. Any
consideration should include an understandi ng that exposure levels in animal studies, in many cases, are greater than exposure levels normally encountered by humans.

A. HUMAN EXPOSURE AND EFFECTS
Studies that measured total mercury, without distinguishing forms of mercury:

< Total mercury has been measured in many types of food (1, 4, 28-30), including infant and toddler foods (26) and children’s diet (28) . Another study estimated mercury ex posure of children from diet in Canada (29). The largest proportion of mercury in diet was attributed to the presence of methylmercury in fish (see Organic Mercury Chemical Summary) (1).

< Total mercury concentrations have been measured in umbilical cord blood (30-36), placenta (31, 32), and fetal hair (32). One study in Tennessee meas ured total mercury in fetal blood, placenta, and maternal blood for over 650 pregnancies, and repo rted significant correla tions between mercury
concentrations in maternal blood and in fetal bl ood (32). In a study of pregnant women in Iowa, increasing blood total mercury concentrations were correlated with the incidence of previous stillbirths, and separately with a history of having children with birth defects (30).

< Total mercury concentrations have also been m easured in blood, urine, fingernails, and hair of children (34, 37-59), as well as in breast milk (31, 34, 60-68). Also, as part of a large national study (National Health and Nutri tion Examination Survey, or NHANES; 1999-2002), total mercury
concentrations were measured in blood of childre n 1-5 years old, and in blood and urine of women 16- 49 years old were measured (69). Results indicated that 5.7% of women 16-49 years old had mean total mercury concentrations in blood higher than 5.8 μ g/L (blood mercury levels below 5.8 μ g/L, the U.S. EPA reference blood level, were estima ted to be without appreciable harm) (52).

< Possible effects of mercury exposure on pregna ncy outcome have been studied. One study found a correlation between increased incidence of miscarriage and total mercury concentrations in well water (70). In a study of pregnant women in Iowa, in creasing blood total mercury concentrations were correlated with the incidence of previous stillbirths, and separately with a history of having children with birth defects (71).

< Longitudinal studies of possible neurodevelopm ental effects of mercury exposure have been performed, measuring total mercury concentrations in hair and blood of pregnant women and their children over time (1, 12). In stud ies from the Faroe Islands and elsewhere, poorer performance on neuropsychological tests in children was associated with higher concen trations of mercury in maternal hair during pregnancy or in cord blood (33, 53, 72-77). Similar corr elations were found in another study in New Zealand (78). In cont rast, other studies in the Seyche lle Islands found few correlations between mercury concentrations in maternal hair and neurological impairments in children (68, 79- 88). Mercury exposures in these st udies were largely attr ibuted to methylmercury exposure from the consumption of fish in the diet (72-74, 79-92). Th ese large studies, in conj unction with other data, have been carefully evaluated and analyzed by th e National Research Council and the U.S. EPA, and provide the basis for derivation of the current U.S. EPA oral refere nce dose (RfD) for methylmercury (91, 92).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 5 < Children’s total mercury blood concentrations were si gnificantly associated with other health effects, including increased N-acetyl-beta-D-glucosaminidas e (a measure of kidney function) and decreased serum prolactin (indicating a shift in neurobi ochemical metabolism) (58). Total mercury
concentrations in blood and in hair were significantly associated wi th decreased logical and spatial abilities (56). There were no significant impair ments in cognitive testing of children amalgam (mercury-containing) dental fillings , as compared to children with composite (mercury-free) fillings (93, 94). More information about mercury exposure from dental amalgam use is summarized in the TEACH Elemental Mercury Chemical Summary.

< Possible associations between autism spectrum disorders (ASD) and environmental exposure to mercury have been explored. Increased incide nce of ASD was associated with mercury air concentration at the census tract level (95), and wi th total reported environmental mercury releases (96). One study reported no significa nt difference in blood concentra tions of total mercury between children with ASD, and children without ASD (97) . More information about mercury exposure from
vaccines is summarized in the TEACH Organic Mercury Chemical Summary.

< Some adverse effects on vision (e.g., reduced contra st sensitivity, with difficu lties sensing shades of gray) in children were significantly associated with increased total mercury concentrations in blood (98). In another study, there was no a ssociation between contrast sensitiv ity in 7-year-old children, and their cord blood total mercury co ncentrations at birth (99).

< Increases in blood pressure and decreases in heart rate variabil ity in 7-year-old children were associated with increasing total mercury concentrations in cord bl ood at their birth (23). A follow-up of those children at 14 years of age revealed that there was no l onger a significant increase in blood pressure associated with cord blood mercury con centrations, though a signif icant association with
decreases in heart rate va riability remained (24).

< Exploring possible thyroid eff ects, one study reported no significan t association between cord blood total mercury concentrations and infant thyroid ho rmone concentrations (35). Another large study of
children found no correlation between blood total mercury levels and blood thyroid hormone levels (100).

Studies that measured inorganic mercury:

< Some studies specifically measur ed concentrations of inorganic mercury in blood and urine from pregnant women and their fetuses (4, 34, 43, 46, 101- 103). One study reported that the majority of mercury in the blood of pregnant women was met hylmercury, and a smaller proportion was inorganic mercury (43). Inorganic mercury can cross the placen ta (101), and has been measured in cord blood (34, 46, 101, 102), and placenta (46, 101-103). Inorganic mercury has been detected in human fetal liver, but not brain (103).

< Inorganic mercury concentrations have been meas ured in children’s blood and urine (4, 7, 10, 39, 41, 43-45, 69) and has been detected in breast milk (34, 66, 104).

< Mothers with higher inorganic mercury blood concen trations (in the highest 5% of concentrations measured in this particular study) we re nine times more likely to have a child with a neural tube defect (105).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 6 < Increasing maternal blood inorga nic mercury concentrations were significantly associated with decreasing maternal blood concen trations of the thyroid hormone , T3; there was no significant association with fetal thyroid hormone concentrations (35).

< Children are most likely to be exposed to high le vels of inorganic mercury via ingestion. Reported acute exposures of children to inor ganic mercury included ingestion of batteries (7) and use of some homeopathic medicines (8, 9, 11). Dermal exposure of children from use of some imported skin bleaching creams has been reported, though currently the sale of skin bleaching creams containing mercury is very uncommon in the U.S. following the U.S. FDA ruling that such creams are not considered generally safe and effective (see U.S. Federal Regulatory Information) (10).

< There are currently few published studies that speci fically address health effects in children following exposure to inorganic mercury. Most studies pertaining to mercury e xposures and effects in children have measured total mercury or methylmercury levels (see each TEACH Chemical Summary for Elemental Mercury and Organic Mercury for additional information).

< Acrodynia (also called “pink disease”) is a syndrome that includes a range of symptoms, and has been associated with exposure to mercury, including inorganic mercury (1, 12) . Associated symptoms include leg cramps, irritability, redness and peeling of skin on ha nds, nose, and soles of the feet. Itching, fever, sweating, salivating, rashes, sleeplessness, and/or wea kness have also been present. Acrodynia was confirmed in Iraq following an in cident where many families were exposed to mercury-contaminated grain between 1955 and 1972 (see the TEACH Organic Mercury Chemical Summary) (1, 12). Acrodynia has also been observed in children, teens, and adults following use of skin bleaching creams (1, 12).

< Neurological effects in children have been report ed following exposure to mercuric chloride or mercuric sulfide (1, 9, 25). Symptoms included neur ological tics (uncontrollab le muscle movements), impaired gait, and convulsions (1, 9, 25).

< There have been a number of case studies of inorganic mercury exposur e involving children. Some herbal remedies may contain inor ganic mercury, and use of these re medies has resulted in adverse health effects in children. Abnormal heart rhythms, increased heart rate, a nd elevated blood pressure were observed in children exposed to mercuric chlori de in older medicinal treatments for worms or for teething discomfort prior to the 1960's; these treatme nts are no longer in use (1). An immune-mediated red, itchy skin rash was reported in a 5-year-old child following e xposure to a homeopathic medicine that contained inorganic mercury (8); the rash was similar to a characteristic rash called “baboon syndrome” which is an acute rash in the buttocks, genital, and anal regions sometimes seen after exposure to mercury or other compounds, including some antibiotics. In a nother study, motor tics (uncontrollable movements) incl uding eye blinking, head turning, and shoulder shrugging in a boy were reported following exposure to inorganic mercury from ingesti on of an herbal remedy in Hong Kong (9).

< No observable health effects were noted in two other reports of children with increased inorganic mercury concentrations in urine as high as 200 μ g/L (7, 10). Note that me rcury concentrations of concern in blood and urine can be qu ite different (see the th ird bullet in this se ction for information about blood mercury concentrations).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 7 B. EXPERIMENTAL ANIMAL EXPOSURE AND EFFECTS Experimental animal studies summarized here involved inorganic mercury exposure.

< The accumulation, tissue distribution, and excreti on of inorganic mercury have been studied in pregnant or developing hamsters (106-108), mice (109-111), and rats (112-115). These studies used protocols of maternal prenat al (106, 107, 112, 114), lactational (107-109, 111, 112, 114), or early life exposure (109, 110, 113, 115). Inorganic mercury accumulate d in fetal liver (106), and in liver, brain, kidney, and plasma of neonatal or young offspri ng (110, 114). One study compared tissue distribution of mercuric chloride and ethlymercury injecti on of nursing pups, and found si gnificant differences in mercury tissue distribution between the two forms of mercury (i.e., more mercury in kidney and liver with mercuric chloride exposure, and more merc ury in blood and brain with thimerosal exposure) (115).

< Inorganic mercury has been shown to cross the placenta in hamsters and rats (106, 107, 112).

< Inorganic mercury was shown to be secreted in breast milk (104, 107, 110-112), and absorbed from breast milk by nursing pups (111). Ne onatal rats demonstrated greater absorption of inorganic mercury in the gastrointestinal tract th an weanling or adult rats (113).

< Inorganic mercury has been detect ed in fetal tissues following methylmercury exposure in hamsters (51, 59). Following methylmercury exposure, inorgani c mercury was detected in fetal liver and brain, suggesting that methylmercury may be processed in the body to form inorganic mercury (106, 107).

< Possible effects of exposure to inorganic mercury on germ cells have been studied. Mercuric chloride exposure had no observable adverse effects on oocytes from exposed hamsters (116) or mice (117). Exposure of adult male or female mice to mercuric chloride prior to mating had reduced numbers of live pups at birth (16, 118). In adult male mice exposed to merc uric chloride with a single intraperitoneal injection, there was decreased fertility and changes in sperm development (119).

< Embryotoxic effects following maternal exposure to mercuric acetate during pregnancy were reported in hamsters (13-15). Increased resorptions (fetal deaths) and increased abnormalities (i.e., retarded growth, exencephaly or exposed brai n tissue, and fused ribs) in offs pring were significantly increased (13-15). The sensitivity of embryos to mercuric acetate toxicity vari ed between strains of hamsters with differing genetic backgrounds (13). Routes of administration of mercuric acetate were compared in one study with hamsters, and the intraperitoneal injection route demonstrated embryotoxic effects at lower doses than other injection si tes, or oral exposure (14). Embr yotoxic effects of mercuric acetate were negated when zinc was co-a dministered during pregnancy (15).

< Following mercuric chloride exposure during pre gnancy, embryotoxic effects were observed in mice and rats. There was a significant redu ction in the percentage of live pups per litter following mercuric chloride exposure via maternal subcutaneous injec tion (13, 16, 18) or intrav enous injection (17, 19). Maternal exposure to mercuric ch loride aerosol via inhalation dur ing pregnancy led to increased incidence of delayed bone ossifica tion in offspring, and increased numbers of dead fetuses (26). Hamsters were more sensitive to embryotoxic effect s of mercuric chloride exposure than mice (17).

< Immune system effects were observed in offspri ng following maternal exposur e to mercuric chloride during pregnancy via drinking wate r (100). As adults, male offspr ing had significantly increased production of some cytokines (e.g., gamma interferon and Interleukin 4) while female offspring had decreased production of these cytokines (120).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 8 < Exposure of neonatal rats to mercur ic chloride by subcutaneous injecti on resulted in changes in growth of brain, heart, kidney, and liver that differed for each type of ti ssue(25, 121), and stabilized toward normal growth over time (27); growth of some or gans increased and some decreased. Levels of ornithine decarboxylase ac tivity, norepinephrine, dopamine, and other neurochemicals were also altered (increased or decreased) in specific areas of the brain following this exposure regimen (27). The metal-binding chelator 2,3-dimercapto-1-propa nol (BAL) was not eff ective in alleviating symptoms of toxicity in one study (121).



### V. CONSIDERATIONS FOR DECISION-MAKERS

This section contains information that may be useful to risk assessors, parents, caregivers, physicians, and other decisionmakers who are interested in re ducing the exposure and adverse health effects in children for this particular chemical. Information in this section focuses on ways to reduce exposure, assess possible exposure, and, fo r some chemicals, administer

treatment.

I nformation About Reducing or Preventing Exposures

< Much information on children’s health following i norganic mercury exposure comes from information published prior to the 1960s (1, 4). The TEACH Data base contains scientif ic articles published in 1972 or later, and therefore doe s not contain these publications ; these articles are summarized elsewhere (1, 4, 12). Many of these earlier studies repor ted effects of exposure to mercuric chloride in
infants and children from the use of some household products, such as diaper creams and laxatives, which, in the past, contained significant amounts of mercuric chloride; these products no longer contain mercury compounds (1, 4).

< Some medications, including ove r-the-counter medications, contai n small amounts of mercury as a preservative, or in solutions to be used as an tiseptics (such as mercur ochrome). The U.S. FDA
maintains a list of medications that contain mercury (122).

< Herbal remedies may contain inorganic mercury, though reported cases of such exposures were the
result of use of herbal remedies from non-U.S. sources (1, 2, 9). Some traditional Chinese and Hispanic remedies for stomach disorders (e.g. herb al balls) may contain inorganic mercury (2).

< Skin-bleaching creams that contain ammoniated mercuric chloride or mercuric iodide can result in mercury exposure (1). The U.S. FDA ruled that thes e skin-bleaching creams ar e not generally safe and effective, and consequently sale of these creams in the U.S. has b een greatly reduced or stopped (see U.S. Regulatory Information in this Chemical Summary).

< Mercury exposure can occur as a consequence of spills from broken thermometers, gauges, or other commercially-available items that contain mercur y (1, 2, 4, 123); for more details see the TEACH Elemental Mercury Chemical Summary. Mercury expos ure can also occur from eating fish, and some types of fish contain more mercury than others (1, 2, 4, 122-124); for more details see the TEACH Organic Mercury Chemical Summary.Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 9 O ther Exposure Information

< Mercury concentrations in hair have been measured as part of the National Human Exposure Assessment Survey (NHEXAS), designed to evalua te human exposure to several chemicals on a regional scale in the U.S.; the fi rst phase of the study was comple ted in 1998 (125). Hair mercury concentrations for 182 people, including children, livi ng in the Midwest have been measured as part of this survey (39).

< Concentrations of mercury in blood and urine of women 16-49 years old a nd children 1-5 years old were measured from 1999-2002 as part of the ong oing National Health and Nutrition Examination Survey (NHANES) list of chemicals (69). This compre hensive survey is administered annually by the
U.S. Centers for Disease Control and Prevention National Center for Health Statistics (69).

< The U.S. EPA used 1999 emissions data for mercur y compounds for all 50 states to report countylevel emissions, modeled ambient air concentrati on estimates, modeled human inhalation exposure, and estimated risk (126).

O ther Information Resources

< The U.S. EPA provides a Web site with a broad ar ray of information resources pertaining to mercury exposure and health effects (123). Detailed compilations and analyses of information pertaining to exposure and health effects of i norganic mercury are presented in the Toxicological Profile for Mercury (1). A Hazard Summary for Mercury Compounds is also available from the U.S. EPA, which
summarizes information derived from several sources (127).

< A detailed health risk assessmen t for mercury and mercury compounds is available as a component of the U.S. EPA “Mercury Study Report to Congress” which contains detailed information about mercury emissions, health and environmental implic ations of those emissions, and emission control technologies (128).

< Mercury and mercury compounds ar e listed as number 3 on the 2005 Priority List of Hazardous Substances for the Comprehensive Environmen tal Response, Compensation, and Liability Act (CERCLA) section 104 (i), as amended by the Superfund Amendments and Reauthorization Act (SARA). This is a list, in the orde r of priority of concern, of substa nces most commonly found at sites listed on the National Priorities list (NPL); ther e are currently 275 substa nces on this list (129). Mercury had been found in at least 714 of 1,467 current or former NPL sites (1).

< Consult the U.S. EPA “Child-Specific Exposure Factors Handbook” (EPA-600-P-00-002B) for factors to assess children’s dermal absorption and inhala tion rates (129). An updated External Draft of the 2006 version of this handbook is available (130).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 10 

### VI. TOXICITY REFERENCE VALUES

Mercuric Chloride

A. Oral/Ingestion

U.S. EPA RfD for Chronic Oral Exposure: 3E-4 (or 0.0003) mg/kg-day; based on autoimmune glomerularnephritis in a dult Brown Norway rats ( http://www.epa.gov/iris/subst/0692.htm , I.A.1) (131). Last Workgroup Ve rification Date 11/16/88.

U.S. EPA Drinking Water Advisories (10 kg child or 22 lb. child): 1 day = 0.002 mg/L, 10 day = 0.002 mg/L ( http://www.epa.gov/ost/drinking/ standards/dwstandards.pdf ) (132). Last revised 5/1/95.

U.S. EPA Maximum Contaminant Le vel (MCL) for Drinking Water: 0.002 mg/L, based on kidney damage in adults ( http://www.epa.gov/safewater/mcl.html#mcls ) (133). Last revised 7/02.

U.S. EPA Maximum Contamin ant Level Goal (MCLG): 0.002 mg/L, based on kidney damage ( http://www.epa.gov/safewater/mcl.html#mcls ) (133). Last revised 7/02.

B. Inhalation

U.S. ATSDR Minimal Risk Level (MRL): 0.007 mg/kg/day (oral acute e xposure, renal effects); 0.002 (oral intermediate exposure, renal effects) ( http://www.atsdr.cdc.gov/mrls/index.html ) (134). Last
revised 3/99.



### VII. U.S. FEDERAL REGU LATORY INFORMATION

< The U.S. FDA ruled that skin bleaching creams c ontaining inorganic mercury (ammoniated mercuric chloride or mercuric iodide) were not generally recognized as safe a nd effective, and subsequent sales of the products in the U.S. were eventually st opped. However, foreign skin-bleaching products containing inorganic mercury have b een found for sale in the U.S., and their use has been reported (1).

< Mercurochrome (merbromin) is an antiseptic solution th at contains small amounts of mercury (2% mercury). The U.S. FDA issued a final rule on April 22, 1998 (63 FR 19799) that merbromin (and other mercury active ingredients) as not generally recognized as sa fe and effective as an active ingredient for over-the-counter (OTC ) first aid antiseptic and antimicrobi al diaper rash uses. Also, the FDA ruled that products containing these ingredie nts for these uses could no longer be initially introduced or initially delivered for introduction into interstate commerce after October 19, 1998. This FDA ruling reduced or eliminated marketing and sales of these products at the re tail level in the U.S., though mercurochrome is readily available in other count ries and still may be in use in the U.S. (135).

< Mercury is one of 188 hazardous air pollutants ( HAPs) listed under section 112(b) of the 1990 Clean Air Act Amendments and is regulated from mo re than 170 industrial source categories (136).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 11 < The U.S. EPA requires reporting of quantities of cer tain chemicals that exceed a defined reportable quantity, and that quantity varies for different chemicals (137). Under the Emergency Planning and Community Right-to-Know Act (EPCRA) Section 313 “T oxic Chemicals,” mercury is classified as a persistent, bioaccumulative and toxic compound (PBT ) and as such, quantities of mercury greater than 10 pounds manufactured or processed, or ot herwise used, is required (137, 138). Under the Comprehensive Environmental Response, Compen sation, and Liability Act (CERCLA), reporting releases of any quantity exceedi ng 1 pound is required (137).

< For a comprehensive list of mercur y regulations and standards, go to http://www.epa.gov/mercury/regs.htm

.



### VIII. BACKGROUND ON CHEMICAL

A. CAS Number: 7487-94-7 (mercuric chloride); 7546-30-7 (mercurous chloride); 1600-27-7 (mercuric acetate); 1344-48-5 (mercuric sulfide); 21908-53-2 (mercuric oxide).

B. Physicochemical Properties: Mercuric chloride is a white powder that is soluble in water. Mercuric
acetate is a white or off-white odorle ss powder. Mercuric sulfide is a bl ack or red powder (differing in color depending on the process used to make the powder). Go to the National Library of Medicine ChemID Web site ( http://chem.sis.nlm.nih.gov/chemidplus ) and search for mercuric chloride, mercuric acetate, or mercuric sulfide.

C. Production: There are several inorganic salts of merc ury, the most common of which is mercuric chloride (1, 2, 5). Examples of ot her inorganic mercury compounds incl ude mercuric sulfate, mercuric sulfide, and mercuric oxide. Inorganic mercury occurs naturally in the environmen t, and is also released as a consequence of human activit ies (1-3). Inorganic mercury is mined and processed to generate elemental mercury. Most of the mercury found in th e environment is elemental and inorganic mercury that was released into air from mercury mining pr ocesses, emissions of co al-fired power plants,
emissions from some solid waste inci nerators, and other indu strial sources (1-3). U.S. production of total mercury in 1995 was estimated to be 158 tons, while world production of total mercury in 1995 was estimated to be 5,500 tons (3). A recent analysis es timated that U.S. production of total mercury from secondary facilities is appr oximately 430 tons/year (139).

D. Uses: Inorganic mercury can be found in some skin-lig htening creams, some homeopathic medicines, and some batteries (1, 2, 5). Mercuric chloride may also be used as a topical antiseptic or disinfectant (1). Mercurous chloride was widely used in laxa tives, worming medications , and teething powders over 40 years ago, but is no longer used in these products (1, 2). Mercuric sulf ide as cinnabar or e is orange in color, and is mined and then processed to form li quid elemental mercury (1, 2). Mercuric sulfide and mercuric oxide are red (or in some preparations, black) in color, and ar e used for pigment in some paints and tattoo dyes (1, 2). In 2004, the total amount of reported releases and disposals of mercury compounds in the U.S. was over 4.7 million pounds (122); to tal releases are likely to be greater than this estimate because not all sources of mercury co mpound releases are required to report (1, 129).Chemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 12 E. Environmental Fate: Mercury is released in the environmen t as a result of bot h natural and human activities, and persists ov er time, though the form in which it exis ts changes over time (1-3). Metallic mercury enters the air from mining ore deposits, bur ning coal and waste, and from manufacturing plants (1-3). It enters the water or soil fr om erosion of natural deposits, discha rge from refineries and factories, and runoffs from landfills and crop lands. Mercury emissions are transported through ambient air, and deposited to water and land where humans and wildlif e can be exposed. Concentrations of mercury in ambient air are usually low and of little direct co ncern (1, 2, 4). Once mercur y enters water, either through air deposition or soil runoff, microorganisms such as bacteria transform inorganic mercury in the environment to methylmercury, which can then bi oaccumulate in fish and animal tissue (1, 2, 4). Higher levels of methylmercury are found in some t ypes of fish (e.g., shark, sw ordfish, and tile fish) than others (see TEACH Organic Merc ury Chemical Summary) (122-124).

F. Synonyms and Trade Names: mercuric chloride, mercuric acetate, mercuric sulfide, mercuric oxide, mercury bichloride, corrosive sublimate, mercuric (II) chloride, mercury perchloride, mercurous (I) chloride, and others. For a mo re complete list, go to http://chem.sis.nlm.nih.gov/chemidplus/ and search for each compound individually.

Additional information on inorgani c mercury is available in the TEACH Database for Inorganic Mercury, and at the following Web sites:

www.epa.gov/glnpo/sediments.html www.epa.gov/ost/fish/mercurydata.html www.epa.gov/mercuryChemical Summary, Inorganic Mercury (continued)

Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

. Last revised 9/21/2007: includes research ar ticles and other information through 2006. Page 13 

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.Chemical Summary, Inorganic Mercury (continued)

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Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

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Supporting references and summaries are provided in the TEACH database at http://www.epa.gov/teach/

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.Chemical Summary, Inorganic Mercury (continued)

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