Technical report: mercury in the environment: implications for pediatricians

Measuring contextual characteristics for community health

OBJECTIVE

To conceptualize and measure community contextual influences on population health and health disparities.

DATA SOURCES

We use traditional and nontraditional secondary sources of data comprising a comprehensive array of community characteristics.

STUDY DESIGN

Using a consultative process, we identify 12 overarching dimensions of contextual characteristics that may affect community health, as well as specific subcomponents relating to each dimension.

DATA COLLECTION

An extensive geocoded library of data indicators relating to each dimension and subcomponent for metropolitan areas in the United States is assembled.

PRINCIPAL FINDINGS

We describe the development of community contextual health profiles, present the rationale supporting each of the profile dimensions, and provide examples of relevant data sources.

CONCLUSIONS

Our conceptual framework for community contextual characteristics, including a specified set of dimensions and components, can provide practical ways to monitor health-related aspects of the economic, social, and physical environments in which people live. We suggest several guiding principles useful for understanding how aspects of contextual characteristics can affect health and health disparities.

'Parsimonious' versus patient-centered care: quality issues in childhood immunization

As currently practiced, the standard of care strictly limiting the number of medical conditions that warrant withholding vaccination may be incompatible with the Institute of Medicine's (IOM) recommendation for patient-centered care. Furthermore, the "parsimonious" approach to accepting contraindications to vaccination is inconsistent with the IOM's recommendation to consider alternative vaccination schedules and policies aimed at redistributing the benefits and burdens of immunization. This critical perspective is examined within the framework of five rules proposed by the IOM. There is an opportunity to improve the quality of childhood immunization by adopting a patient-centered approach, identifying individuals at risk for acute and/or delayed adverse vaccine effects, and developing alternative immunization schedules for these high-risk children.

Environmental health of children

Pediatric primary health care providers are responsible for providing comprehensive care to children. This includes assessing for and identifying the effect of environmental hazards on children's health and managing conditions that may result from exposure to environmental toxins. This article begins by reviewing the unique developmental, biologic, and behavioral characteristics of children and age-specific issues that make them particularly vulnerable to toxins. It then provides the reader with general assessment and management strategies related to environmental toxins, including an assessment tool that can be used in a pediatric primary care office. The qualities of selected toxins that have been implicated in childhood illnesses are discussed. Routes of exposure, signs and symptoms of toxicity, and assessment and management approaches are presented specifically for lead, mercury, environmental tobacco smoke, particulate matter, asbestos, radon, molds, and pesticides. Because prevention is the best intervention in environmental health, the article emphasizes ways pediatric providers can work with caregivers to prevent or minimize exposure.

Decline in fish consumption among pregnant women after a national mercury advisory

OBJECTIVE

A well-publicized January 2001 federal advisory recommended that pregnant women limit consumption of certain fish because of concerns about mercury contamination. We endeavored to estimate the extent to which pregnant women changed fish consumption habits after dissemination of this national advisory.

METHODS

We performed interrupted time series analysis of data from a cohort of pregnant women (2235 who completed at least one dietary questionnaire) visiting obstetric offices in a multispecialty group practice in eastern Massachusetts, surveyed before the advisory from April 1999 through December 2000 and after the advisory from April 2001 through February 2002. Main outcome measures were consumption of total fish and of four fish types: canned tuna, dark meat fish, shellfish, and white meat fish. Subjects reported fish consumption on semiquantitative food frequency questionnaires administered at each trimester of pregnancy.

RESULTS

We observed diminished consumption of dark meat fish, canned tuna, and white meat fish after the national mercury advisory. These decreases resulted in a reduction in total fish consumption of approximately 1.4 servings per month (95% confidence interval 0.7, 2.0) from December 2000 to April 2001, with ongoing declines through the end of the study period. There was no change in shellfish intake.

CONCLUSION

After dissemination of federal recommendations, pregnant women in this cohort reported reduced consumption of fish, including tuna, dark meat fish, and white meat fish. Because these fish may confer nutritional benefits to mother and infant, public health implications of these changes remain unclear.

Environmental exposure to mercury and its toxicopathologic implications for public health

Mercury is a toxic and hazardous metal that occurs naturally in the earth's crust. Natural phenomena such as erosion and volcanic eruptions, and anthropogenic activities like metal smelting and industrial production and use may lead to substantial contamination of the environment with mercury. Through consumption of mercury in food, the populations of many areas, particularly in the developing world, have been confronted with catastrophic outbreaks of mercury-induced diseases and mortality. Countries such as Japan, Iraq, Ghana, the Seychelles, and the Faroe Islands have faced such epidemics, which have unraveled the insidious and debilitating nature of mercury poisoning. Its creeping neurotoxicity is highly devastating, particularly in the central and peripheral nervous systems of children. Central nervous system defects and erethism as well as arrythmias, cardiomyopathies, and kidney damage have been associated with mercury exposure. Necrotizing bronchitis and pneumonitis arising from inhalation of mercury vapor can result in respiratory failure. Mercury is also considered a potent immunostimulant and -suppressant, depending on exposure dose and individual susceptibility, producing a number of pathologic sequelae including lymphoproliferation, hypergammaglobulinemia, and total systemic hyper- and hyporeactivities. In this review we discuss the sources of mercury and the potential for human exposure; its biogeochemical cycling in the environment; its systemic, immunotoxic, genotoxic/carcinogenic, and teratogenic health effects; and the dietary influences on its toxicity; as well as the important considerations in risk assessment and management of mercury poisoning.

Neurophysiological anomalies in brainstem responses of mercury-exposed children of Andean gold miners

The health hazards of occupational exposure to Mercury (Hg) in adult gold miners are well known, but little attention has been given to the effects of Hg exposure in the children of gold miners. Children who assist their parents in gold mining operations or live in mining enclaves may be exposed to elemental Hg vapors or methylmercury-contaminated food, both of which may induce neurodevelopmental disabilities. Brainstem auditory-evoked responses (BAER) were measured as biomarkers of subtle mercury-induced neurological impairment in Andean children of gold miners living in the Ecuadorian gold mining settlement of Nambija, where Hg exposure is prevalent. Thirty-one children (19 boys and 12 girls, aged 4-14 years, mean age: 10 years) in the study group were found to have a mean blood mercury (HgB) level of 23.0 micrograms/L (SD: 19, range: 2.0-89.0 micrograms/L; median: 20 micrograms/L), which was significantly higher than the mean HgB level of a reference group of 21 Ecuadorian children (4.5 micrograms/L, SD: 2.3; t = 4.39, P = 0.0001), and in excess of the health-based biological limits for the U.S. (10 micrograms/L). The BAER measures indicated statistically significant differences in interpeak III-V (P = 0.03) and I-V (P = 0.008) neural conduction times for children with HgB levels above the median. BAERs at the conventional click stimulus rate of 10/second showed statistically significant positive correlations between HgB level and the absolute latency of wave V (P = 0.03), and the neural conduction times of the eighth nerve to midbrain I-V interval (P = 0.02). BAER at 50/second revealed statistically significant relationships between HgB and the latency of wave VI (P = 0.03), and the I-VI interpeak interval (P = 0.02). Brainstem neural conduction times suggested that some of the Hg-intoxicated children in the study group have subtle neurophysiological anomalies that may be more manifest at higher BAER stimulus rates, and that the Hg-exposed children of gold miners are at risk for neurodevelopmental disabilities.

Recent dietary guidelines to prevent and treat cardiovascular disease, diabetes, and obesity

Nutrition guidelines are emphasizing dietary patterns as primary and secondary prevention trials provide increasing evidence of the importance of lifestyle changes to prevent/control cardiovascular disease (CVD) risk factors such as diabetes and hypertension. Despite the increasing evidence that weight loss and modified dietary patterns are effective, there is considerable debate about the level of carbohydrate that will be most beneficial. Epidemiologic studies indicate that certain ethnic and racial minority groups have increased CVD risk with higher rates of obesity, hypertension, diabetes, and stroke. Immigrant and Native American populations have had a dramatic rise in obesity, diabetes, and ultimately CVD with acculturation, accompanied by a higher fat intake and decreased physical activity. Culturally tailored intervention approaches are being used to reduce risk. The lack of third-party payment still limits the availability of nutrition services. However, medical nutrition therapy is covered by Medicare for diabetes and pending legislation will extend coverage to CVD. Medical education researchers have developed tools such as the WAVE (Weight, Activity, Variety and Excess) pocket guide as a quick method to facilitate addressing referral for medical nutrition therapy that can be readily incorporated into practice settings.

The science of evaluation of adverse events associated with vaccination

All vaccines cause some adverse events; serious adverse events are rare. Causal associations between a vaccine and an adverse event rarely can be determined by specific tests such as identifying a vaccine agent in the affected tissue of patients. In the absence of such data, epidemiologic studies can be used to determine if the risk of the disorder is increased in vaccinated compared to unvaccinated individuals. Common mistakes include assuming a causal relationship based on a temporal association only or a series of affected patients. Careful studies have demonstrated that many hypothesized causal associations between vaccines and adverse events were not substantiated. False assumptions regarding causality are likely to occur for illnesses without a carefully defined etiology or pathogenesis.

How should a fever mercury thermometer be disposed of ? A survey of those likely to be asked

The American Academy of Pediatrics' recent technical report entitled "Mercury in the Environment: Implications for Pediatricians" was widely reported on by the news media. After the media reports, the New Jersey Poison Information and Education System experienced a notable increase in the volume of calls on this topic. We surveyed local, county, and state health officers who would likely be contacted by citizens with the question: "How should a fever mercury thermometer be disposed of?" Our initial contacts with health officers corroborated our caller's account: a lack of uniformity of response. This led us to question if there was any consensus in advice being offered to the public at large.