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Comments on “Probabilistic mercury multimedia exposure assessment in small children and risk assessment”
EI-02596; No of Pages 1 Environment International xxx (2013) xxx
Contents lists available at ScienceDirect
Environment International journal homepage: www.elsevier.com/locate/envint
Letter to the Editor Comments on “Probabilistic mercury multimedia exposure assessment in small children and risk assessment” Keywords: Mercury Risk assessment Thimerosal Methylmercury Ethylmercury Breastfeeding
Dear Editor, The field of health risk assessment related to Hg exposure in young children is enriched by the Morisset et al. (2013) paper; this work is both interesting and important. It is interesting because it addresses mercury exposure at the most vulnerable stage of neurodevelopment; and, it is important because it was conceptualized (“to understand multimedia exposure to various forms of mercury in infants”) for a world wide application in at-risk-populations. While I welcome their interesting findings with interest, I would like to address their take home message on infant feeding practices and total Hg exposure issues. Their results identified “only elemental mercury by inhalation route (indoor air) and methylmercury by ingestion (fish and breast-milk) seem to lead to a health risk in small children.” However they concluded “(t)hese results confirm the importance of assessing total mercury concentration in media like breastmilk, indoor air and dust and methylmercury level in food, other than fish and seafood. In this way, informed monitoring plan and risk assessment in an at-risk sub-population can be set.” Because the model used to assess mercury exposure was based on breast milk and formulas, their findings and interpretations ended up with the inescapable reasoning that formula feeding would lead to less health risk. Therefore, for anyone contemplating using a similar model—especially those residing in developing countries, it is important that we expand and contextualize their results regarding feeding practices (breast milk and formulas) and health risk in regard to Hg exposure from all sources. Morisset et al. used data of Hg in air, breast milk, and formulas (including water) to represent all sources of exposure to nursing infants in France. They assumed a breast-milk intake of 769 mL/day, and came up with 0.262 μg Hg/kg bw/week which they compared with a Taiwanese study (2.037 μg/kg bw/week) based on a much higher milk Hg concentration (2.03 μg/L) and lower milk intake (400–500 mL) than that expected for nursing French babies; this value was considered high by Morisset et al. Actually, the world median of reported breastmilk mean Hg concentration is 2.0 μg/L (Dórea, 2004). Despite these differences, Morisset et al. still underestimated Taiwanese infants' exposure to organic Hg sources.
In Taiwan, as in most of the world (outside North America and the EU—including France) infants are also exposed to comparatively higher levels of ethylmercury during immunization with Thimerosal containing vaccines (TCV) (Dórea, 2007) than in France. Newborns receiving the birth vaccine against hepatitis B preserved with Thimerosal (as a single jab) will be exposed to ethylmercury levels much higher (7.5 μg/kg bw; Dórea et al., 2009) than that estimated for breastfeeding in France (0.262 μg Hg/kg bw/week) and Taiwan (2.037 μg/kg bw/week) in a week. Actually, depending on the birth weight and vaccine maker, the birth dose can range from 4.2 to 21.1 μg ethyl-Hg/kg bw (Dórea et al., 2009). Studies like Morisset et al. illustrate the need to accurately determine Hg exposure (and cumulative health risks) resulting from both environmental (methylmercury) and purposeful infant's exposures from ethylmercury in all immunizations with TCVs. Finally, it is important to emphasize that Morisset et al. did not make any apology for formula feeding and their results should be strictly limited for use in France (and countries that do not use pediatric TCV). For other countries, especially those with populations consuming fish, their model grossly underestimates “multimedia exposure to various forms of mercury in infants”. Notwithstanding, Morisset et al. demonstrated the existing disparity in total Hg exposure in early life, reminding us that “The ban of mercury could decrease exposure” but other forms of Hg exposure would always lead to health risks when they overrun toxicological reference values. Besides educating mothers to choose low-Hg fish species we need to press for policies that address the ethical obligation to follow the path of developed nations and adopt Thimerosalfree vaccines for pregnant mothers and young children. The optimal health risk assessment of Hg exposure during early life is crucial for protecting brain development. So, it must consider all sources of Hg exposure. As a result, we need to be sensitive about how health-risk-assessment studies, like this one, can impact health professionals everywhere who advise parents on infant feeding and immunization practices—especially with regard to total Hg exposure during the neonatal period. References Dórea JG. Mercury and lead during breast-feeding. Br J Nutr 2004;92:21–40. Dórea JG. Exposure to mercury during the first six months via human milk and vaccines: modifying risk factors. Am J Perinatol 2007;24:387–400. Dórea JG, Marques RC, Brandão KG. Neonate exposure to thimerosal mercury from hepatitis B vaccines. Am J Perinatol 2009;26:523–7. Morisset T, Ramirez-Martinez A, Wesolek N, Roudot AC. Probabilistic mercury multimedia exposure assessment in small children and risk assessment. Environ Int 2013;59C: 431–41.
José G. Dórea Department of Nutrition, Faculty of Health Sciences, Universidade de Brasilia, 70919-970 Brasilia, DF, Brazil E-mail address: [email protected].
0160-4120/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.envint.2013.08.015
Please cite this article as: Dórea JG, Environ Int (2013), http://dx.doi.org/10.1016/j.envint.2013.08.015
15 August 2013 Available online xxxx
Contents lists available at ScienceDirect
Environment International journal homepage: www.elsevier.com/locate/envint
Letter to the Editor Comments on “Probabilistic mercury multimedia exposure assessment in small children and risk assessment” Keywords: Mercury Risk assessment Thimerosal Methylmercury Ethylmercury Breastfeeding
Dear Editor, The field of health risk assessment related to Hg exposure in young children is enriched by the Morisset et al. (2013) paper; this work is both interesting and important. It is interesting because it addresses mercury exposure at the most vulnerable stage of neurodevelopment; and, it is important because it was conceptualized (“to understand multimedia exposure to various forms of mercury in infants”) for a world wide application in at-risk-populations. While I welcome their interesting findings with interest, I would like to address their take home message on infant feeding practices and total Hg exposure issues. Their results identified “only elemental mercury by inhalation route (indoor air) and methylmercury by ingestion (fish and breast-milk) seem to lead to a health risk in small children.” However they concluded “(t)hese results confirm the importance of assessing total mercury concentration in media like breastmilk, indoor air and dust and methylmercury level in food, other than fish and seafood. In this way, informed monitoring plan and risk assessment in an at-risk sub-population can be set.” Because the model used to assess mercury exposure was based on breast milk and formulas, their findings and interpretations ended up with the inescapable reasoning that formula feeding would lead to less health risk. Therefore, for anyone contemplating using a similar model—especially those residing in developing countries, it is important that we expand and contextualize their results regarding feeding practices (breast milk and formulas) and health risk in regard to Hg exposure from all sources. Morisset et al. used data of Hg in air, breast milk, and formulas (including water) to represent all sources of exposure to nursing infants in France. They assumed a breast-milk intake of 769 mL/day, and came up with 0.262 μg Hg/kg bw/week which they compared with a Taiwanese study (2.037 μg/kg bw/week) based on a much higher milk Hg concentration (2.03 μg/L) and lower milk intake (400–500 mL) than that expected for nursing French babies; this value was considered high by Morisset et al. Actually, the world median of reported breastmilk mean Hg concentration is 2.0 μg/L (Dórea, 2004). Despite these differences, Morisset et al. still underestimated Taiwanese infants' exposure to organic Hg sources.
In Taiwan, as in most of the world (outside North America and the EU—including France) infants are also exposed to comparatively higher levels of ethylmercury during immunization with Thimerosal containing vaccines (TCV) (Dórea, 2007) than in France. Newborns receiving the birth vaccine against hepatitis B preserved with Thimerosal (as a single jab) will be exposed to ethylmercury levels much higher (7.5 μg/kg bw; Dórea et al., 2009) than that estimated for breastfeeding in France (0.262 μg Hg/kg bw/week) and Taiwan (2.037 μg/kg bw/week) in a week. Actually, depending on the birth weight and vaccine maker, the birth dose can range from 4.2 to 21.1 μg ethyl-Hg/kg bw (Dórea et al., 2009). Studies like Morisset et al. illustrate the need to accurately determine Hg exposure (and cumulative health risks) resulting from both environmental (methylmercury) and purposeful infant's exposures from ethylmercury in all immunizations with TCVs. Finally, it is important to emphasize that Morisset et al. did not make any apology for formula feeding and their results should be strictly limited for use in France (and countries that do not use pediatric TCV). For other countries, especially those with populations consuming fish, their model grossly underestimates “multimedia exposure to various forms of mercury in infants”. Notwithstanding, Morisset et al. demonstrated the existing disparity in total Hg exposure in early life, reminding us that “The ban of mercury could decrease exposure” but other forms of Hg exposure would always lead to health risks when they overrun toxicological reference values. Besides educating mothers to choose low-Hg fish species we need to press for policies that address the ethical obligation to follow the path of developed nations and adopt Thimerosalfree vaccines for pregnant mothers and young children. The optimal health risk assessment of Hg exposure during early life is crucial for protecting brain development. So, it must consider all sources of Hg exposure. As a result, we need to be sensitive about how health-risk-assessment studies, like this one, can impact health professionals everywhere who advise parents on infant feeding and immunization practices—especially with regard to total Hg exposure during the neonatal period. References Dórea JG. Mercury and lead during breast-feeding. Br J Nutr 2004;92:21–40. Dórea JG. Exposure to mercury during the first six months via human milk and vaccines: modifying risk factors. Am J Perinatol 2007;24:387–400. Dórea JG, Marques RC, Brandão KG. Neonate exposure to thimerosal mercury from hepatitis B vaccines. Am J Perinatol 2009;26:523–7. Morisset T, Ramirez-Martinez A, Wesolek N, Roudot AC. Probabilistic mercury multimedia exposure assessment in small children and risk assessment. Environ Int 2013;59C: 431–41.
José G. Dórea Department of Nutrition, Faculty of Health Sciences, Universidade de Brasilia, 70919-970 Brasilia, DF, Brazil E-mail address: [email protected].
0160-4120/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.envint.2013.08.015
Please cite this article as: Dórea JG, Environ Int (2013), http://dx.doi.org/10.1016/j.envint.2013.08.015
15 August 2013 Available online xxxx