Mercury Exposure from Dental Filling Placement during Pregnancy and Low Birth Weight Risk

P. P. Hujoel1,2, M. Lydon-Rochelle3, A. M. Bollen4, J. S. Woods5, W. Geurtsen6 and M. A. del Aguila2,7

1 Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA
2 Department of Dental Public Health Sciences, School of Dentistry, University of Washington, Seattle, WA
3 Department of Family and Child Nursing, School of Nursing, University of Washington, Seattle, WA
4 Department of Orthodontics, School of Dentistry, University of Washington, Seattle, WA
5 Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA
6 Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA
7 Washington Dental Service, Seattle, WA

Reprint requests to Dr. Philippe Hujoel, University of Washington Department of Dental Public Health Sciences, Health Sciences Center, B-509, Seattle, WA 98195-7475 (e-mail: hujoel{at}u.washington.edu).

Received for publication July 19, 2004. Accepted for publication December 10, 2004.


    ABSTRACT
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Several European countries have guidelines suggesting that women should not receive mercury-containing dental amalgam fillings during pregnancy. One concern raised by several studies is that mercury exposure during pregnancy may lead to decreased birth weight. A population-based, case-control study was designed to investigate whether placement of mercury-containing fillings in 1993–2000 during pregnancy increased the low-birth-weight risk. Cases and controls were sampled from enrollees of a dental insurance plan with live singleton births in Washington State; 1,117 women with low-birth-weight infants (<2,500 g) were compared with a random sample of 4,468 women with infants weighing 2,500 g or more. The results indicated that 13% of a dentally insured population had one or more restorative procedures during pregnancy that, regardless of chemical composition, did not increase the low-birth-weight risk (odds ratio = 0.96, 95% confidence interval: 0.88, 1.05). The 4.9% of the women (n = 249) who had at least one mercury-containing amalgam filling during pregnancy were not at an increased risk for a low-birth-weight infant (odds ratio = 0.75, 95% confidence interval: 0.45, 1.26) and neither were women who had 4–11 amalgam fillings placed (odds ratio = 1.00, 95% confidence interval: 0.27, 3.68). This study found no evidence that mercury-containing dental fillings placed during pregnancy increased low-birth-weight risk.

birth weight; case-control studies; dentistry; estrogens; infant, low birth weight; mercury; pregnancy; risk


    INTRODUCTION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
The World Health Organization reported that the vast majority of adults in industrialized countries have dental caries (1Go) and that billions of dental fillings are placed worldwide to restore decayed or damaged teeth (2Go). The safety of these filling materials has remained largely unregulated partly because they were widely used prior to the emergence of government regulations, and partly because filling materials are most commonly considered devices by regulatory governmental organizations and, as a result, escape the more strict safety regulations present for pharmaceutical products (2Go). All dental amalgams contain elemental mercury, which has led to concerns for their use (3Go, 4Go) during pregnancy. The main source of exposure to mercury vapor in the general population is dental amalgam (5Go) and, based on available evidence, Austria, Germany, Finland, Norway, the United Kingdom, and Sweden have advised dentists to specifically avoid mercury-containing amalgam fillings during pregnancy (2Go).

The rationale for these advisories is based in part on the precautionary principle that dental amalgam contains and releases mercury, a naturally occurring metal which at higher levels can be an environmental pollutant, and which has been associated in an animal model with fetal growth retardation (6Go). In humans, mercury exposure has been associated with delayed neurodevelopment (7Go–9Go) and low birth weight (10Go–12Go). Upon the placement of dental amalgam, the urinary mercury concentrations increase approximately ninefold within the first week, reaching a peak concentration of approximately 8 µg of mercury for a 24-hour urine sample. Recommendation to abandon mercury-containing amalgam fillings during pregnancy is not without potential risks. Resin-based dental filling materials, the most common alternative to mercury-containing dental amalgams, can leach estrogen-like molecules that in animal models have been associated with an abnormal number of chromosomes in eggs, fetal loss, and other adverse pregnancy outcomes (13Go, 14Go). Several countries have expressed the need for better epidemiologic research to establish evidence-based guidelines on the use of dental filling materials during pregnancy. The goal of this study was to determine the potential associations between mercury-containing dental fillings placed during pregnancy and risk of low-birth-weight infants. A secondary aim was to evaluate whether resin-based materials affected birth weight.


    MATERIALS AND METHODS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Design and subjects
A population-based, case-control study was conducted linking dental utilization data from Washington Dental Service, a not-for-profit dental insurance company, to Vital Records birth certificates from Washington State. Women between the ages of 12 and 45 years, with a dental treatment between January 1, 1993, and December 31, 2000, were identified, and a client file was created that contained the first and last names, address, city, ZIP Code, and birth date. This file was sent to the birth certificate data manager, who created a unique identifier for each record and linked the data to the Vital Records birth certificates using both deterministic and probabilistic matching procedures. Only singleton births were included.

The combination of the mother's exact birth date along with the mother's first name and either the father's last name or mother's maiden name gave a conclusive match for 94.1 percent of the matched sample of women. The exact date of mother's birth, along with a partial name match, accounted for a further 2.7 percent of matches. Partial name matches and either an address match (0.5 percent) or a transposed date of mother's birth year, month, or day segment (2.7 percent) accounted for the remaining matches. During this matching process, the Washington Dental Service data manager received infants' birth dates only from the birth certificate data manager, and the birth certificate data manager did not receive dental utilization data from Washington Dental Service. All successful matches combined with infants' birth dates (n = 29,215) were sent back to Washington Dental Service, where it was determined whether eligibility for dental services existed during a period 40 weeks prior to birth and for how many months eligibility existed. Prior to 1995, eligibility for dental services could be determined only for those women who had at least one dental visit, whereas subsequent to 1995 eligibility could be determined regardless of whether a dental visit occurred. This change in method of determining eligibility did not impact the reported findings.

The unique identifiers of those women eligible for dental services during pregnancy were sent to the birth certificate data manager, who then selected the case-control study population. The case group consisted of all pregnancies resulting in low-birth-weight infants. Four normal birth weight infants (2,500–5,414 g) were randomly selected for each case without matching. Both the Washington Dental Service and birth certificate data managers stripped the data files of personal identifiers and sent them to the University of Washington, where linking occurred using the patient unique identifier. Human subject approval was obtained from the Human Research Review Board of the Washington State Department of Health.

Outcome and exposure data
Low birth weight was defined as any liveborn infant weighing less than 2,500 g. Dentists submit information on both the type of restorative material used and the date the restoration was inserted intraorally to Washington Dental Service, a not-for-profit dental insurance company, where it is archived in an electronic database. The information was stored using American Dental Association codes, where code 1351 represents a sealant; codes 2330–2337, 2380–2382, and 2385–2388 represent resin-based fillings; codes 2140, 2150, and 2160–2161 represent amalgams; and codes 2710–2799 represent crowns. For all analyses, the number of restorative procedures women received since the last menstrual period was calculated and summarized using three statistics: the insertion of at least one filling during pregnancy (yes/no), the number of teeth filled per woman (possible range: 0–32 teeth), and the number of surfaces filled per woman (possible range: 0–128 surfaces).

Confounding variables
Together, the birth certificate records and the dental utilization data provided information on the following potential confounding variables: dental radiation doses (0, 0.1–0.4, >0.4 mGy); maternal age at the time of delivery (categorized into <20, 20–24, 25–29, 30–34, 35–39, ≥40 years); ethnicity (Caucasian, African American, Asian, and other ethnicities); the duration of eligibility for dental insurance during pregnancy (continuous); marital status (yes/no); parity (0, 1–2, ≥3 prior pregnancies); self-reported maternal smoking during pregnancy (yes/no); the presence of gestational or established diabetes (yes/no); the Kessner Index of adequacy of prenatal care (15Go) (adequate, intermediate, inadequate); educational level of mother (less than high school, more than high school, unknown); self-reported consumption of one or more alcoholic drinks per week during pregnancy (yes/no); weight gain during pregnancy (continuous variable); prepregnancy weight (continuous variable); preeclampsia (yes/no); chronic hypertension (yes/no); and the eight different nonrestorative types of dental care procedures performed during pregnancy (continuous).

Statistical analysis
Between 1993 and 2000, a total of 5,179 women had one singleton birth, 197 women had two singleton births, and four women had three singleton births. To take into account that the pregnancy outcomes for women with more than one birth are correlated events, generalized estimating equation models with independence correlation structures were used for all analyses. Risk factors for low birth weight were evaluated using generalized linear models with an independence correlation structure, a logit link, and a binomial error distribution. To evaluate whether restorative materials are associated with an increased birth weight, we limited the analyses to infants with a birth weight greater than 2,500 g, and generalized linear models were used with an independence correlation structure, an identity link, and a normal error distribution.


    RESULTS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Description of cases and controls
One or more amalgam fillings were placed during pregnancy in 3.5 percent of the women with a low-birth-weight infant and in 5.3 percent of the women with an infant having a birth weight of greater than or equal to 2,500 g (table 1). There were no substantial differences with respect to the number of resin-based fillings, sealants, or crowns placed during pregnancy. Standard medical and socioeconomic risk factors for low birth weight were confirmed. When compared with mothers whose infant(s) weighed greater than or equal to 2,500 g, mothers with a low-birth-weight infant were more likely to be less than 20 years of age, less likely to be Caucasian, less likely to have more than a high school degree, and more likely to have had inadequate prenatal care (table 1). Self-reported cigarette smoking during pregnancy, established or gestational diabetes, zero parity, and preecclampsia were identified as risk factors for low birth weight. Dental procedures other than restorative procedures were similar in both groups with the exceptions of orthodontic procedures, which were more prevalent among women with low-birth-weight infants, and preventive procedures, which were more prevalent among women with infants with a birth weight greater than or equal to 2,500 g (table 2).


View this table:
[in this window]
[in a new window]
 
TABLE 1. Characteristics of women giving birth to low-birth-weight infants and normal birth weight infants, Washington State, 1993–2000

 

View this table:
[in this window]
[in a new window]
 
TABLE 2. Dental procedures of women with infants weighing <2,500 g and ≥2,500 g, Washington State, 1993–2000

 
Mercury and low-birth-weight risk
As shown in table 3, the odds for a low-birth-weight infant were significantly lower among women who had one or more dental amalgams placed during pregnancy (odds ratio = 0.65, 95 percent confidence interval: 0.46, 0.92). After adjustment for sociodemographic and medical risk factors for low birth weight, placement of amalgam fillings was no longer significantly associated with the odds for a low-birth-weight infant (odds ratio = 0.68, 95 percent confidence interval: 0.42, 1.09) (table 3). Further adjustment for potential dental risk factors did not significantly alter this association (odds ratio = 0.70, 95 percent confidence interval: 0.44, 1.13). When either the number of teeth with amalgam fillings or the number of surfaces on teeth with amalgam fillings was evaluated, similar findings were identified. Similarly, when the analyses were restricted to women who did not receive resin-based restorative materials during pregnancy, amalgam was not associated with an increased risk for low birth weight (table 3).


View this table:
[in this window]
[in a new window]
 
TABLE 3. Odds ratios for low birth weight* associated with women's receiving amalgam fillings during gestation and the effect of adjustment for confounders, Washington State, 1993–2000

 
Potential dose-response relations were determined by evaluating women with no amalgam fillings, women with 1–4 amalgam fillings, and women with 5–11 amalgam fillings. Neither crude nor adjusted odds ratios suggested the presence of an association. After adjustment for both medical and dental risk factors of low birth weight, the odds ratio associated with 1–4 amalgam fillings was 0.67 (95 percent confidence interval: 0.41, 1.11), and the odds ratio associated with 5–11 amalgam fillings was 1.00 (95 percent confidence interval: 0.27, 3.68).

Significant associations were not observed either when the odds for term low birth weight associated with having at least one mercury-containing amalgam filling were evaluated (odds ratio = 1.07, 95 percent confidence interval: 0.59, 1.94). When a dose-response relation was evaluated, the odds ratio associated with 1–4 amalgam fillings was 1.05 (95 percent confidence interval: 0.57, 1.95), and the odds ratio associated with 5–11 amalgam fillings was 1.36 (95 percent confidence interval: 0.16, 11.23).

Resin-based fillings and birth weight
A secondary aim of the study was to evaluate the association among resin-based filling materials, sealants, and birth weight. Before or after adjustment for sociodemographic, medical, or dental potential confounders, there was no association between the use of resin-based materials and low birth weight (table 3) (odds ratio = 0.83, 95 percent confidence interval: 0.55, 1.25). There also was no association identified between the number of teeth or surfaces filled with resins and the odds for low birth weight (table 4). When the analyses were limited to women who did not receive amalgam fillings or sealants, similar associations were observed between resin-based restorations and low birth weight (table 4).


View this table:
[in this window]
[in a new window]
 
TABLE 4. Odds ratios for low birth weight* associated with resin-based fillings during gestation and the impact of control for competing risk factors, Washington State, 1993–2000

 
The association between sealants and low birth weight showed a similar pattern, although the decreased incidence of low birth weight was more marked here. After adjustment for sociodemographic, medical, or potential dental risk factors of low birth weight, there was a 70 percent decreased odds ratio for low birth weight associated with the placement of sealant (95 percent confidence interval: 0.07, 1.35). Further analyses based on the number of sealants per woman did not identify any significant associations.

When the analyses were limited to women with infants of normal birth weight (≥2,500 g), there was no association between the number of amalgam fillings, resin-based fillings, or sealants and birth weight. For every additional sealant, the birth weight increased by 3 g (95 percent confidence interval: –41 to 47; p = 0.89); for every tooth with a resin-based filling, the birth weight increased by 5 g (95 percent confidence interval: –12 to 22; p = 0.59); and for every amalgam filling, the birth weight decreased by 9 g (95 percent confidence interval: –32 to 15; p = 0.48). These analyses were adjusted for all the potential confounding variables listed in table 2.

Restorative materials, regardless of chemical composition, and low birth weight
The odds for a low-birth-weight infant were not associated with the number of restorative procedures performed during pregnancy (odds ratio = 0.95, 95 percent confidence interval: 0.88, 1.02). Adjustment for the potential sociodemographic, medical, and dental risk factors for low birth weight did not alter this finding of no association between birth weight and restorative procedures (odds ratio = 0.96, 95 percent confidence interval: 0.88, 1.05).


    DISCUSSION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
The placement of mercury-containing dental fillings during pregnancy did not result in an increased risk of a low-birth-weight infant. While a weak dose-response trend was observed for term low-birth-weight infants, both the small size of the risk increase and the width of the confidence intervals precluded making any meaningful inferences, and associations were not identified between restorative dental procedures, regardless of chemical composition, and birth weight. These findings do not provide support to the hypothesis that mercury-containing dental amalgams placed during pregnancy affect birth weight. Potential reasons for the absence of an association include the low dose of inorganic mercury exposure associated with dental filling placement during pregnancy, the absence of organic mercury in dental filling materials, and the true absence of a biologic mechanism by which elemental mercury affects birth weight.

Because the mercury in dental amalgam was thought to exist in a metallic crystalline form, it was long believed that no mercury escaped from the completed dental restoration. In recent years, however, the development of highly sensitive methods for the detection and examination of the fate of mercury in dental amalgams has shown that mercury is released from dental amalgam fillings in the form of mercury vapor, and that the rate of this release is dependent upon several factors. For instance, nicotine gum chewing can increase the exposure to mercury to levels close to occupational health limits (16Go). The dose of elemental mercury absorbed from dental amalgam restorations has been reported to range from approximately 2.9 to 17.5 µg/day (17Go–21Go). Estimates of absorbed elemental mercury from ambient sources are one to two orders of magnitude less, ranging from 32 to 96 ng/day. Placement of new dental amalgams leads to eightfold increases in mercury intake and, when combined with preexisting amalgams, may lead to a peak intake of 100–200 µg of mercury per week (22Go). Clarkson et al. (23Go) have estimated that, for the general US population, the dominant exposure for elemental mercury is to mercury vapor from dental amalgam fillings.

An important consideration in the interpretation of these values is the chemical form of the mercury exposure. Mercury vapor readily crosses the placenta and accumulates in the fetus as a result of mercury's high lipid solubility. It is not clear if elemental mercury released by dental amalgams remains entirely in the inorganic form after exposure. It has been shown that three common intraoral strains can transform elemental mercury to methylmercury (7Go), raising the possibility that similar transformations may occur in vivo, possibly in the oral cavity or in the gut. This is an important consideration, since organic mercury can be toxic at very low doses (<1 mg/day) and, at high doses, has been associated with severe toxicity effects (24Go, 25Go). Some countries have guidelines to limit the intake of organic mercury. For instance, the US Food and Drug Administration reports that pregnant women should not consume more than 0.01 µg of methylmercury per kilogram per day (approximately two cans of tuna).

Our ability to estimate actual mercury exposure subsequent to amalgam placement in this population of pregnant women is limited by several factors. First, the type of material removed prior to the placement of the dental amalgam was not known. If the insertion of a mercury-containing dental filling was preceded by the removal of a prior amalgam filling, higher levels of mercury exposure are to be expected than if carious tooth material or non-mercury-containing dental materials are removed. This weakness was somewhat attenuated by the knowledge that restorative procedures of any type were not associated with an increased risk for low birth weight. Second, we did not have information on the number of existing amalgam fillings prior to pregnancy. The chronic long-term, low-level release of mercury from these fillings may have confounded the acute higher-level exposure associated with placement of a dental amalgam. Third, because the increased mercury exposure associated with amalgam placement is short term and because the estimate of the last menstrual period is inaccurate, there may be some misclassification with respect to the determination of mercury exposure during pregnancy. Inaccuracies in the birth certificate records may have further diluted our ability to detect associations.

While this is the first study evaluating the effects of dental filling materials on low birth weight, some important questions remain unanswered. This study was not designed to evaluate the effect of mercury on chromosomal alterations, neurobehavioral characteristics, or other possible adverse pregnancy outcomes such as spontaneous abortions. In addition, this study was not designed to evaluate the effects of resin-based filling materials on pregnancy outcomes. The safety profile of resin-based filling materials is considerably more difficult to establish because of significant product variability and analytical complexity. Composite-based filling materials are of concern because of the presence of estrogen-like molecules, which are an environmental pollutant and which have been associated with chromosomal abnormalities in mice, fetal loss, and an increased birth weight soon after birth (4Go), as well as with underdevelopment of the brain, kidney, and testes in mice (26Go).

Because our study was specifically designed to evaluate risks for low birth weight, we were limited in our ability to assess whether resin-based filling materials increase birth weight. Analysis limited to those women with an infant weighing 2,500 g or more could not identify an association between resin-based, tooth-filling materials and increased birth weight. Case-control studies specifically designed to detect macrosomia (>4,000 g) will be more sensitive to detect any potential association between plastic filling materials and increased birth weight.

In summary, the present study could not identify an increased risk for a low-birth-weight infant among those women receiving mercury-containing dental amalgam fillings. Further evaluations of the safety profiles of dental amalgams, resin-based fillings, and other types of dental materials used intraorally are required to establish evidence-based guidelines for usage of dental materials during pregnancy.


    References
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 

  1. Petersen PE. The World Oral Health Report 2003: continuous improvement of oral health in the 21st century—the approach of the WHO Global Oral Health Programme. Community Dent Oral Epidemiol 2003;31(suppl 1):3–23.[CrossRef][ISI][Medline]
  2. Anderson BA, Arenholt-Bindslev D, Cooper IR, et al. Dental amalgam—a report with reference to the medical devices directive 93/42/EEC from an Ad Hoc Working Group mandated by DGIII of the European Commission. Angelholm, Sweden: Nordiska Dental AB, 1998. (http://www.nordiskadental.se/EUamalgam/eumain.htm).
  3. Takai Y, Tsutsumi O, Ikezuki Y, et al. Preimplantation exposure to bisphenol A advances postnatal development. Reprod Toxicol 2001;15:71–4.[CrossRef][ISI][Medline]
  4. Rubin BS, Murray MK, Damassa DA, et al. Perinatal exposure to low doses of bisphenol A affects body weight, patterns of estrous cyclicity, and plasma LH levels. Environ Health Perspect 2001;109:675–80.[ISI][Medline]
  5. World Health Organization. Inorganic mercury. In: Environmental health criteria. Vol 118. Geneva, Switzerland: World Health Organization, 1991.
  6. Gale TF, Ferm VH. Embryopathic effects of mercuric salts. Life Sci II 1971;10:1341–7.[CrossRef][Medline]
  7. Heintze U, Edwardsson S, Derand T, et al. Methylation of mercury from dental amalgam and mercuric chloride by oral streptococci in vitro. Scand J Dent Res 1983;91:150–2.[ISI][Medline]
  8. Bjornberg KA, Vahter M, Petersson-Grawe K, et al. Methyl mercury and inorganic mercury in Swedish pregnant women and in cord blood: influence of fish consumption. Environ Health Perspect 2003;111:637–41.[ISI][Medline]
  9. Leistevuo J, Leistevuo T, Helenius H, et al. Dental amalgam fillings and the amount of organic mercury in human saliva. Caries Res 2001;35:163–6.[CrossRef][ISI][Medline]
  10. Ericson A, Kallen B. Pregnancy outcome in women working as dentists, dental assistants or dental technicians. Int Arch Occup Environ Health 1989;61:329–33.[CrossRef][ISI][Medline]
  11. Seidler A, Raum E, Arabin B, et al. Maternal occupational exposure to chemical substances and the risk of infants small-for-gestational-age. Am J Ind Med 1999;36:213–22.[CrossRef][ISI][Medline]
  12. Sikorski R, Paszkowski T, Szprengier-Juszkiewicz T. Mercury in neonatal scalp hair. Sci Total Environ 1986;57:105–10.[CrossRef][ISI][Medline]
  13. Cohen J. Lab accident reveals potential health risk of common compound. Science 2003;300:31–2.[ISI][Medline]
  14. Hunt PA, Koehler KE, Susiarjo M, et al. Bisphenol A exposure causes meiotic aneuploidy in the female mouse. Curr Biol 2003;13:546–53.[CrossRef][ISI][Medline]
  15. Kessner D, Singer J, Kalk C, et al. Infant death: an analysis by maternal risk and health care. Washington, DC: Institute of Medicine and National Academy of Sciences, 1973.
  16. Sallsten G, Thoren J, Barregard L, et al. Long-term use of nicotine chewing gum and mercury exposure from dental amalgam fillings. J Dent Res 1996;75:594–8.[Abstract/Free Full Text]
  17. Abraham JE, Svare CW, Frank CW. The effect of dental amalgam restorations on blood mercury levels. J Dent Res 1984;63:71–3.[Abstract/Free Full Text]
  18. Effects of physical forces on the reproductive cycle. Council on Scientific Affairs. JAMA 1984;251:247–50.[Abstract]
  19. Patterson JE, Weissberg BG, Dennison PJ. Mercury in human breath from dental amalgams. Bull Environ Contam Toxicol 1985;34:459–68.[ISI][Medline]
  20. Vimy MJ, Luft AJ, Lorscheider FL. Estimation of mercury body burden from dental amalgam: computer simulation of a metabolic compartmental model. J Dent Res 1986;65:1415–19.[Abstract/Free Full Text]
  21. Svare CW, Peterson LC, Reinhardt JW, et al. The effect of dental amalgams on mercury levels in expired air. J Dent Res 1981;60:1668–71.[Abstract/Free Full Text]
  22. Schneider V. Mercury excretion from silver amalgam fillings, determined by flameless atomic absorption. (In German). Dtsch Zahnarztl Z 1977;32:475–6.[Medline]
  23. Clarkson TW, Friberg L, Hursh JB, et al. The prediction of intake of mercury vapor from amalgams. In: Biological monitoring of toxic metals. New York, NY: Plenum Press, 1988:247–64.
  24. World Health Organization and the United Nations Environment Programme. Environmental health criteria 1. Mercury. Geneva, Switzerland: World Health Organization, 1976. (http://www.inchem.org/documents/ehc/ehc/ehc001.htm).
  25. Bakir F, Damluji SF, Amin-Zaki L, et al. Methylmercury poisoning in Iraq. Science 1973;181:230–41.[ISI][Medline]
  26. Kabuto H, Amakawa M, Shishibori T. Exposure to bisphenol A during embryonic/fetal life and infancy increases oxidative injury and causes underdevelopment of the brain and testis in mice. Life Sci 2004;74:2931–40.[CrossRef][ISI][Medline]




This Article
Abstract
FREE Full Text (PDF)
Alert me when this article is cited
Alert me if a correction is posted
Services
Email this article to a friend
Similar articles in this journal
Similar articles in ISI Web of Science
Similar articles in PubMed
Alert me to new issues of the journal
Add to My Personal Archive
Download to citation manager
Search for citing articles in:
ISI Web of Science (1)
Disclaimer
Request Permissions
Google Scholar
Articles by Hujoel, P. P.
Articles by del Aguila, M. A.
PubMed
PubMed Citation
Articles by Hujoel, P. P.
Articles by del Aguila, M. A.