Impact of Prenatal Methylmercury Exposure on Child Neurodevelopment in the Faroe Islands Katsuyuki MURATA and Miwako DAKEISHI Department of Hygiene, A

Size: px

Start display at page:

Download "Impact of Prenatal Methylmercury Exposure on Child Neurodevelopment in the Faroe Islands Katsuyuki MURATA and Miwako DAKEISHI Department of Hygiene, A"

きみかずあいしま
4 years ago
Views:

1 Impact of Prenatal Methylmercury Exposure on Child Neurodevelopment in the Faroe Islands Katsuyuki MURATA and Miwako DAKEISHI Department of Hygiene, Akita University School of Medicine, Akita Abstract Recent interest concerning methylmercury that accumulates in the aquatic food chain appears to be directed not to the adverse effects of high-dose exposure in humans, but to the critical concentration at which methylmercury may affect the progeny of the exposed population. In epidemiological studies, however, uncertainties and limitations in estimating exposure make it difficult to quantify dose-response associations and can thereby lead to inaccuracies when deriving such concentrations. In this respect, benchmark dose calculation for quantitative outcomes may shed new light on the epidemiological procedure for estimating the critical concentration. After the epidemic outbreaks of methylmercury poisoning in Japan and Iraq, large-scale follow-up studies were carried out in the Faroe Islands, Seychelles and New Zealand, to clarify the effects of prenatal methylmercury exposure on child neurodevelopment in the latter half of the 1980s. This article presents an overview of the outcomes obtained from the Faroe Islands Prospective Study, as well as a brief interpretation of the benchmark dose calculation. Although the Faroe and Seychelles Islands studies did not seem to differ greatly in the study setting, such as the exposure level and sample size, the former study observed some significant dose-effect relationships between methylmercury concentrations at birth and neurobehavioral end-points, but the latter failed to find any significant associations except in one test. The discrepancy between the two conclusions is also discussed. Reprint requests to: Katsuyuki MURATA Department of Hygiene, Akita University School of Medicine, Hondo, Akita , Japan TEL: +81(18) , FAX: +81(18)

Fig. 1 Dose-effect relationship between a certain hazardous substance and intelligence quotient (IQ) in an exposed population for benchmark dose (BMD) calculation.

4 Fig. 1 Dose-effect relationship between a certain hazardous substance and intelligence quotient (IQ) in an exposed population for benchmark dose (BMD) calculation. P0 and benchmark response (BMR) indicate an abnormal rate in the unexposed population and an increased rate above P0 in the exposed population, respectively. That is, BMD is the dose of the substance that results in the increased probability of abnormal IQ, i. e., from P0 to P0+BMR.

5 Health Organization, (1) Kurland LT, Faro SN, Siedler H. Minamata disease: the outbreak of a neurologic disorder in Minamata, Japan, and its relationship to the ingestion of seafood contaminated by mercuric compounds. World Neurol 1959; 1: (2) International Programme on Chemical Safety. Methylmercury (Environmental Health Criteria 101). Geneva: World (3) Igata A. Epidemiological and clinical features of Minamata disease. Environ Res 1993; 63:

(5) Bakir F, Damluji SF, Amin-Zaki L, Murtadha M, Khalidi A, al-rawi NY, Tikriti S, Dahahir HI, Clarkson TW, Smith JC, Doherty RA. Methylmercury poisoning in Iraq. Science 1973; 181: 230-241.

6 (5) Bakir F, Damluji SF, Amin-Zaki L, Murtadha M, Khalidi A, al-rawi NY, Tikriti S, Dahahir HI, Clarkson TW, Smith JC, Doherty RA. Methylmercury poisoning in Iraq. Science 1973; 181: (6) Cox C, Clarkson TW, Marsh DO, Amin-Zaki L, Tikriti S, Myers GG Dose-response analysis of infants prenatally exposed to methyl mercury: an application of a single compartment model to single-strand hair analysis. Environ Res 1989; 49: (8) Committee on the Toxicological Effects of Methylmercury. Toxicological Effects of Methylmercury. Washington, DC: National Academy Press, (9) Kjellstrom T, Kennedy P, Wallis S. Physical and mental development of children with prenatal exposure to mercury from fish. Stage 2, interviews and psychological tests at age 6 (Report 3642). Stockholm: National Swedish Environmental Protection Board, (10) Marsh DO, Clarkson TW, Myers GJ, Davidson PW, Cox C, Cernichiari E, Tanner MA, Lednar W, Shamlaye C, Choisy 0, Hoareau C, Berlin M. The Seychelles study of fetal methylmercury exposure and child development: introduction. Neurotoxicology 1995; 16: (11) Shamlaye C, Marsh DO, Myers GJ, Cox C, Davidson PW, Choisy O, Cernichiari E, Choi A, Clarkson TW. The Seychelles Child Development Study on neurodevelopmental outcomes in children following in utero exposure to methylmercury from a maternal fish diet: background and demographics. Neurotoxicology 1995; 16: (12) Davidson PW, Myers G, Cox C, Shamlaye CF, Marsh DO, Tanner MA, Berlin M, Sloane-Reeves J, Cernichiari E, Choisy O, Choi A, Clarkson TW. Longitudinal neurodevelopmental study of Seychellois children following in utero exposure to methylmercury from a maternal fish ingestion: outcomes at 19 and 29 months. Neurotoxicology 1995; 16: (13) Davidson PW, Myers GJ, Cox C, Axtell C, Shamlaye C, Sloane-Reeves J, Cernichiari E, Needham L, Choi A, Wang Y, Berlin M, Clarkson TW. Effects of prenatal and postnatal methylmercury exposure from fish consumption at 66 months of age. JAMA 1998; 280: (14) Grandjean P, Weihe P, Jorgensen PJ, Clarkson T, Cernichiari E, Videro T. Impact of maternal seafood diet on fetal exposure to mercury, selenium, and lead. Arch Environ Health 1992; 47: (15) Weihe P, Grandjean P. Sources and magnitude of mercury exposure in the Faroe Islands: overall design of the cohort study. In: Proceedings of the International Symposium on Assessment of Environmental Pollution and Health Effects from Methylmercury. Kumamoto: National Institute for Minamata Disease, 1994; (16) Weihe P, Hansen JC, Murata K, Debes F, Jorgensen PJ, Steuerwald U, White RF, Grandjean P. Neurobehavioral performance of Inuit children with increased prenatal exposure to methylmercury. Int J Circumpolar Health 2002; 61: (17) Gaggi C, Zino F, Duccini M, Renzoni A. Levels of mercury in scalp hair of fishermen and their families from Camara de Lobos - Madeira (Portugal): a preliminary study. Bull Environ Contam Toxicol 1996; 56: (18) Renzoni A, Zino F, Franchi E. Mercury levels along the food chain and risk for exposed populations. Environ Res 1998; 77: (19) Abe T, Ohtsuka R, Hongo T, Suzuki T, Tohyama C, Nakano A, Akagi H, Akimichi T. High hair and urinary mercury levels of fish eaters in nonpolluted environment of Papua New Guinea. Arch Environ Health 1995; 50: (20) Kaiser J. Mercury report backs strict rules. Science 2000; 289: (21) Grandjean P, White RF, Weihe P. Evidence of developmental methylmercury toxicity. In: Abstract of 6th International Conference on Mercury as a Global Pollutant. Minamata: Organizing Committee & Steering Committee of 6th IC- MGP, 2001: 233. (22) Dalgard C, Grandjean P, Jorgensen PJ, Weihe P. Mercury in the umbilical cord: implications for risk assessment for Minamata disease. Environ Health Perspect 1994; 102: (23) Akagi H, Grandjean P, Takizawa Y, Weihe P. Methylmercury dose estimation from umbilical cord concentrations in patients with Minamata disease. Environ Res 1998; 77: (24) Weihe P, Grandjean P: Intervention study on methylmercury in the Faroe Islands. In: Abstract of 6th International Conference on Mercury as a Global Pollutant. Minamata: Organizing Committee & Steering Committee of 6th ICMGP, 2001; 234. (25) Dahl R, White RF, Weihe P, Sorensen N, Letz R, Hudnell K, Otto DA, Grandjean P. Feasibility and validity of three computer-assisted neurobehavioral tests in 7-year old children. Neurotoxicol Teratol 1996; 18: (26) Grandjean P, Weihe P, White RF, Debes F, Araki S, Yokoyama K, Murata K, Sorensen N, Dahl R, Jorgensen PJ. Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury. Neurotoxicol Teratol 1997 ; 19: (27) Grandjean P, Weihe P, White RF, Debes F. Cognitive performance of children prenatally exposed to "safe" levels of methylmercury. Environ Res 1998; 77: (28) Steuerwald U, Weihe P, Jorgensen PJ, Bjerve K, Brock J, Heinzow B, Budtz-Jorgensen E, Grandjean P. Maternal seafood diet, methylmercury exposure, and neonatal neurologic function. J Pediatr 2000; 136: (29) Murata K, Weihe P, Araki S, Budtz-Jorgensen E, Grandjean P. Evoked potentials in Faroese children prenatally exposed to methylmercury. Neurotoxicol Teratol 1999 ; 21: (30) Murata K, Weihe P, Renzoni A, Debes F, Vasconcelos R, Zino R, Araki S, Jorgensen PJ, White RF, Grandjean P. Delayed evoked potentials in children exposed to methylmer-

7 cury from seafood. Neurotoxicol Teratol 1999; 21: (31) Grandjean P, Weihe P, Burse VW, Needham LL, Storr- Hansen E, Heinzow B, Debes F, Murata K, Simonsen H, Ellefsen P, Budtz-Jorgensen E, Keiding N, White RF. Neurobehavioral deficits associated with PCB in 7-year-old children prenatally exposed to seafood neurotoxicants. Neurotoxicol Teratol 2001; 23: (32) Mol NM, Sorensen N, Weihe P, Andersson A-M, Jorgensen N, Skakkebaek NE, Keiding N, Grandjean P. Spermaturia and serum hormone concentrations at puberty age in boys prenatally exposed to polychlorinated biphenyls. Eur J Endocrinol 2002; 146: (33) Grandjean P, Budtz-Jorgensen E, White RF, Jorgensen PJ, Weihe P, Debes F, Keiding N. Methylmercury exposure biomarkers as indicators of neurotoxicity in children aged 7 years. Am J Epidemiol 1999; 150: (34) Crump KS. Calculation of benchmark doses from continuous data. Risk Anal 1995; 15 : (35) Crump KS, Viren J, Silvers A, Clewell H III, Gearhart J, Shipp A. Reanalysis of dose-response data from the Iraqi methylmercury poisoning episode. Risk Anal 1995; 15: (36) Crump KS, Van Landingham C, Shamlaye C, Cox C, Davidson PW, Myers GJ, Clarkson TW. Benchmark concentrations for methylmercury obtained from the Seychelles Child Development Study. Environ Health Perspect 2000; 108: (37) Budtz-Jorgensen E, Grandjean P, Keiding N, White RF, Weihe P. Benchmark dose calculations of methylmercuryassociated neurobehavioural deficits. Toxicol Left 2000; : (38) Crump KS, Kjellstrom T, Shipp AM, Silvers A, Stewart A. Influence of prenatal mercury exposure upon scholastic and psychological test performance: benchmark analysis of a New Zealand Cohort. Risk Anal 1998; 18: (39) Murata K, Weihe P, Araki S, Grandjean P. Delayed evoked potentials in children exposed to methylmercury from seafood: Madeira and Faroe Islands. In: Proceedings of US-Japan Workshop on Human Health Effects of Low Dose Methylmercury Exposure. Minamata: National Institute for Minamata Disease, 2001; (40) Murata K, Budtz-Jorgensen E, Grandjean P. Benchmark dose calculations for methylmercury-associated delays on evoked potential latencies in two cohorts of children. Risk Anal 2002; 22: (41) Sorensen N, Murata K, Budtz-Jorgensen E, Weihe P, Grandjean P. Prenatal methylmercury exposure as a cardiovascular risk factor at seven years of age. Epidemiology 1999; 10:

資料１(目消し版).ppt

資料１(目消し版).ppt 1 Dr. Grandjean 2 15 45 3 4 CH 3 Hg + Hg 0 fi Hg ++ fich 3 + MeHg MeHg 5 Methylmercury-2 6 :, A. Yasutake 7 - A. Yasutake 8 :,. A. Yasutake 9 A. Yasutake 10 (%) : : : : : MeHg 0.05 250 : 2 : 1 : 0.1 :