Last update Dec. 5, 2023

Mercuric chloride, yellow mercuric oxide, mercurous chloride, thiomersal, mercurochrome, Merbromin

Likely Compatibility

Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.

Mercury, quicksilver or hydrargyrium (Hg) is a toxic metal that, in its various forms (metallic or elemental, inorganic compounds and organic compounds) behaves as an environmental pollutant harmful to health, with neurological and renal toxicity. (MedlinePlus 2021, WHO/WHO 2017, ATSDR 2015 and 2012

The bioavailability of mercury is highly variable depending on its state (Hale, MedlinePlus 2021, ATSDR 2012):

  • Metal or elemental Hg (from thermometers, dental amalgams, fluorescent bulbs): 0.01% by the oral route and > 80% by inhalation.
  • Inorganic Hg from Hg disk batteries: 7-15% by oral route
  • Organic Hg (phenylmercury, methylmercury from contaminated fish and shellfish, disinfectants such as thimerosal, mercurochrome): 90% by oral route

The main route of human exposure is the consumption of fish and shellfish contaminated with methylmercury, an organic compound present in these foods. Methylmercury is very different from ethylmercury. Ethylmercury is used as a preservative in some vaccines and does not pose a health risk. (WHO 2017)

According to several authors (Hale, Yusà 2017, Al-Saleh 2015, Pitkin 1976), expert committees (FAO, WHO, USA-EPA, EFSA, CDC) establish :

  • A maximum concentration in breast milk of 1.7 μg/L
  • A maximum tolerable weekly intake of 4 μg/kg for Hg metal and 1.6 μg/kg/week for methylmercury
  • A maximum hair concentration of 1 to 1,9 μg/g
  • A maximum 24-hour urine or blood concentration of 5 μg/L

Elevated amounts of mercury in the body are mainly associated with the consumption of fish and offal (Freire 2022, Marques 2016, Al-Saleh 2015, Vieira 2013, Barghi 2012, Orün 2012, Drexler 1998) and to a much lesser extent and without clinical implications with the use of dental amalgams (Rebelo 2017, Al-Saleh 2015, Vieira 2013, Jimenez 2013 Barghi 2012, Norouzi 2012, Richardson 2011, Roberts 2009,US-FDA 2009, da Costa 2005, Ursinyova 2005, Ekstrand 1998, Drexler 1998, Klemann 1990), thimerosal-containing vaccines (Marques 2007) and, in some countries to the consumption of cereals and vegetables (Cherkani 2021, Rebelo 2017), of polyvitamins and lipstick use (Cherkani 2021) and of pollution from gold mining. (Barbosa 1998)

With elevated levels of Hg in breast milk (mean 2.6 μg/L), the mean weekly Hg intake for the infant was half the maximum tolerable (Rebelo 2017), but was higher in some infants whose mothers had very high levels (mean 3.6 μg/L) of Hg in breast milk. (Cherkani 2021, Norouzi 2012)

No neurodevelopmental impairment has been seen in infants breastfed for 6-24 months by mothers with very high hair Hg levels (12 μg/g) due to high fish consumption. (Marques 2016)

No association has been found between Hg in breast milk and Hg in urine and hair of infants:  Infants are exposed to maternal Hg during pregnancy, not during lactation. (Al-Saleh 2015, Barbosa 1998).

Fish consumption, due to its content of omega-3 fatty acids (DHA and EPA), is very beneficial for the health of the mother and the health and neurodevelopment of the infant. Fish with a very low mercury content (salmon, trout, herring, anchovy, sardine) should be chosen, tilefish, shark, swordfish and mackerel should be avoided and tuna consumption should be limited to 170 g per week. (DGA 2010)

Breastfeeding is contraindicated in case of acute or chronic poisoning with compatible clinical symptoms and/or elevated levels of Hg in 24-hour urine or breast milk. Mild exposure due to fish consumption, dental amalgams (US-FDA 2021 and 2017, Ekstrand 1998, Drasch 1998, Klemann 1990), thimerosal-containing vaccines, Hg-containing lamps, does not contraindicate breastfeeding.


The R-risk phrases or Hazard H-phrases and precautionary P-phrases on the labelling that relate to breastfeeding are (INSHT 2022, UN 2011, EC Regulation 2008):

  • H362 (ant. R64): 'May harm breastfed infants'.
  • P263: "Avoid contact during pregnancy and lactation".

Other phrases to consider are:

  • H350 (ant.R45 and R49): "May cause cancer""
  • H351 (ant. R40): "Possible carcinogenic effects"
  • H370 (ant. R39): "Causes damage to organs"
  • H371 (ant. R68): "May cause damage to organs".
  • H372 (ant R48): Same as H370, but "after prolonged or repeated exposure"
  • H373 (ant R33): Same as H371, but "after prolonged or repeated exposure".

As the Hg MSDS contains the phrases H372 and H373 (INSHT 2022), the exposed breastfeeding mother should be moved from her workstation

The benefits of breastfeeding outweigh the risk from low levels of environmental contaminants in human milk, in many cases lower than in cow's milk or other foods. (Diaz 2013).

Informed choice is based on an assessment of the known and unknown risks of artificial feeding against the potential but unproven risks of chemical contamination of breastmilk. (Pronczuk 2002)

See below the information of this related product:

  • Dental Filling (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Mercuric chloride, yellow mercuric oxide, mercurous chloride, thiomersal, mercurochrome, Merbromin is also known as Mercury. Here it is a list of alternative known names::

Mercuric chloride, yellow mercuric oxide, mercurous chloride, thiomersal, mercurochrome, Merbromin in other languages or writings:


Mercuric chloride, yellow mercuric oxide, mercurous chloride, thiomersal, mercurochrome, Merbromin belongs to these groups or families:


Main tradenames from several countries containing Mercuric chloride, yellow mercuric oxide, mercurous chloride, thiomersal, mercurochrome, Merbromin in its composition:


Variable Value Unit
Oral Bioavail. Variable %
Molecular weight 201 daltons
1680 hours


  1. Freire C, Iribarne-Durán LM, Gil F, Olmedo P, Serrano-Lopez L, Peña-Caballero M, Hurtado JA, Alvarado-González NE, Fernández MF, Peinado FM, Artacho-Cordón F, Olea N. Concentrations and determinants of lead, mercury, cadmium, and arsenic in pooled donor breast milk in Spain. Int J Hyg Environ Health. 2022 Mar;240:113914. Abstract
  2. INSHT - Instituto Nacional de Seguridad e Higiene en el Trabajo. Límites de exposición profesional para agentes químicos en España. - 2022 Full text (link to original source) Full text (in our servers)
  3. U.S. Food and Drug Administration. About Dental Amalgam Fillings None 2021 Full text (link to original source)
  4. MedlinePlus. Mercury poisoning. Health topics. 2021 Full text (link to original source) Full text (in our servers)
  5. Cherkani-Hassani A, Slaoui M, Ghanname I, Mojemmi B, Belhaj A, Kers B, Flayou M, Mouane N. Levels of mercury in Moroccan breast milk and the affecting factors: CONTAMILK study. Regul Toxicol Pharmacol. 2021 Dec;127:105065. Abstract
  6. MedlinePlus. Intoxicación con mercurio. Temas de Salud. 2021 Full text (link to original source) Full text (in our servers)
  7. WHO. Mercury and health. Fact sheet. 2017 Full text (link to original source) Full text (in our servers)
  8. Yusà V, Pérez R, Suelves T, Corpas-Burgos F, Gormáz M, Dualde P, Coscolla C, Quiles J, Roca M, Vento M. Biomonitoring of mercury in hair of breastfeeding mothers living in the Valencian Region (Spain). Levels and predictors of exposure. Chemosphere. 2017 Nov;187:106-113. Abstract
  9. Rebelo FM, Cunha LRD, Andrade PD, Costa Junior WAD, Bastos WR, Caldas ED. Mercury in breast milk from women in the Federal District, Brazil and dietary risk assessment for breastfed infants. J Trace Elem Med Biol. 2017 Dec;44:99-103. Abstract
  10. U.S. Food and Drug Administration. Appendix I : Summary of Changes to the Classification of Dental Amalgam and Mercury. None 2017 Full text (link to original source)
  11. OMS. El mercurio y la salud. Temas de salud. 2017 Full text (link to original source) Full text (in our servers)
  12. Marques RC, Abreu L, Bernardi JV, Dórea JG. Traditional living in the Amazon: Extended breastfeeding, fish consumption, mercury exposure and neurodevelopment. Ann Hum Biol. 2016 Jul;43(4):360-70. Abstract
  13. ATSDR. Mercury and Your Health. online. 2015 Full text (link to original source)
  14. Al-Saleh I, Abduljabbar M, Al-Rouqi R, Eltabache C, Al-Rajudi T, Elkhatib R, Nester M. The extent of mercury (Hg) exposure among Saudi mothers and their respective infants. Environ Monit Assess. 2015 Nov;187(11):678. Abstract
  15. Vieira SM, de Almeida R, Holanda IB, Mussy MH, Galvão RC, Crispim PT, Dórea JG, Bastos WR. Total and methyl-mercury in hair and milk of mothers living in the city of Porto Velho and in villages along the Rio Madeira, Amazon, Brazil. Int J Hyg Environ Health. 2013 Abstract
  16. Jiménez L. Empastes de amalgama de mercurio ¿Son tóxicos y peligrosos? ¿Tienes que preocuparte por tu salud? El Blog de Centinel. 2013 Full text (link to original source) Full text (in our servers)
  17. Díaz-Gómez NM, Ares S, Hernández-Aguilar MT, Ortega-García JA, Paricio-Talayero JM, Landa-Rivera L; Comité de Lactancia Materna de la Asociación Española de Pediatría.. Contaminantes químicos y lactancia materna: tomando posiciones. [Chemical pollution and breast milk: Taking positions]. An Pediatr (Barc). 2013 Dec;79(6):391.e1-5. Abstract Full text (link to original source) Full text (in our servers)
  18. Orün E, Yalçin SS, Aykut O, Orhan G, Koç-Morgil G, Yurdakök K, Uzun R. Mercury exposure via breast-milk in infants from a suburban area of Ankara, Turkey. Turk J Pediatr. 2012 Abstract
  19. Norouzi E, Bahramifar N, Ghasempouri SM. Effect of teeth amalgam on mercury levels in the colostrums human milk in Lenjan. Environ Monit Assess. 2012 Abstract
  20. Barghi M, Behrooz RD, Esmaili-Sari A, Ghasempouri SM. Mercury exposure assessment in Iranian pregnant women's hair with respect to diet, amalgam filling, and lactation. Biol Trace Elem Res. 2012 Abstract
  21. ATSDR/CDC. Evaluating Mercury Exposure: Information for Health Care Providers. Fact sheet 2012 Full text (link to original source)
  22. ATSDR/CDC. Evaluación de la exposición al mercurio: información para profesionales sanitarios. Hoja de datos 2012 Full text (link to original source)
  23. Richardson GM, Wilson R, Allard D, Purtill C, Douma S, Gravière J. Mercury exposure and risks from dental amalgam in the US population, post-2000. Sci Total Environ. 2011 Abstract
  24. DGA 2010 - U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th Edition, Washington, DC - 2010 Full text (link to original source)
  25. U.S. Food and Drug Administration. White Paper: FDA Update/Review of Potential Adverse Health Risks Associated with Exposure to Mercury in Dental Amalgam. 2009 Full text (link to original source) Full text (in our servers)
  26. Roberts HW, Charlton DG. The release of mercury from amalgam restorations and its health effects: a review. Oper Dent. 2009 Abstract Full text (link to original source) Full text (in our servers)
  27. Marques RC, Dórea JG, Fonseca MF, Bastos WR, Malm O. Hair mercury in breast-fed infants exposed to thimerosal-preserved vaccines. Eur J Pediatr. 2007 Sep;166(9):935-41. Epub 2007 Jan 20. Abstract
  28. da Costa SL, Malm O, Dórea JG. Breast-milk mercury concentrations and amalgam surface in mothers from Brasília, Brazil. Biol Trace Elem Res. 2005 Abstract
  29. Ursinyova M, Masanova V. Cadmium, lead and mercury in human milk from Slovakia. Food Addit Contam. 2005 Abstract
  30. Pronczuk J, Akre J, Moy G, Vallenas C. Global perspectives in breast milk contamination: infectious and toxic hazards. Environ Health Perspect. 2002 Abstract Full text (link to original source) Full text (in our servers)
  31. Ekstrand J, Björkman L, Edlund C, Sandborgh-Englund G. Toxicological aspects on the release and systemic uptake of mercury from dental amalgam. Eur J Oral Sci. 1998 Abstract
  32. Drasch G, Aigner S, Roider G, Staiger F, Lipowsky G. Mercury in human colostrum and early breast milk. Its dependence on dental amalgam and other factors. J Trace Elem Med Biol. 1998 Abstract
  33. Barbosa AC, Dórea JG. Indices of mercury contamination during breast feeding in the Amazon Basin. Environ Toxicol Pharmacol. 1998 Oct;6(2):71-9. Abstract
  34. Drexler H, Schaller KH. The mercury concentration in breast milk resulting from amalgam fillings and dietary habits. Environ Res. 1998 Abstract
  35. Klemann D, Weinhold J, Strubelt O, Pentz R, Jungblut JR, Klink F. [Effects of amalgam fillings on the mercury concentrations in amniotic fluid and breast milk]. Dtsch Zahnarztl Z. 1990 Abstract
  36. Pitkin RM, Bahns JA, Filer LJ Jr, Reynolds WA. Mercury in human maternal and cord blood, placenta, and milk. Proc Soc Exp Biol Med. 1976 Mar;151(3):565-7. Abstract

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