While the US Environmental Protection Agency’s methylmercury reference dose is justifiable based on the latest scientific evidence, each year approximately 60,000 children may be born in the US with neurological problems that could lead to poor school performance because of exposure to methylmercury in utero, says a report from the National Research Council. Congress requested the Council to review the scientific basis for setting exposure limits for methylmercury.
“Although we believe EPA’s guideline on methylmercury is generally adequate to protect most people, more must be done to gain a better understanding of various risk factors for the US population,” said Robert A. Goyer, chair of the committee that wrote the report and Professor Emer¬itus at the University of Western Ontario.
The committee found that neuro-developmental problems are the most appropriate basis for setting an exposure limit. According to the committee, strong scientific evidence from human and animal studies links certain levels of methylmercury exposure and neurological problems. However, researchers still need to understand if there is a precise time during development when the brain is most sensitive to methylmercury.
Scientists do not agree on how to account for some uncertainties, such as varying individual responses to methylmercury exposure; better data are needed to decrease these uncertainties, the report says. For example, further investigation is needed on low-dose exposure to methylmercury throughout the life spans of humans and animals, and on carcinogenic, neurologic, reproductive, and immunologic effects, including the emergence of delayed neurological effects later in life.
In the US, responsibility for regu¬lating mercury is shared by two fed¬eral agencies: the EPA and the Food and Drug Administration (FDA). The FDA is charged with regulating com¬mercially sold fish and seafood. The EPA monitors concentrations in the environment and regulates industrial releases of mercury to surface water and air.
The EPA’s reference dose is an estimate of the amount of methyl¬mercury to which an individual can be exposed on a daily basis without adverse health consequences. The reference dose is used to guide regu-111 omen and Heart Disease: An If If Atlas of Racial and Ethnic Disparities in Mortal it)1, developed by West Virginia University and the Cardiovascular Health Branch of the US Centers for Disease Control and Prevention, provides data on geographic, racial, and ethnic inequalities in women’s heart disease death rates. The Atlas includes more than 200 national and state maps of heart disease mortality and related top¬latory policies ranging from fish con¬sumption advisories to air emission permits.
To reach its conclusions, the committee evaluated the data on which the risk assessments conducted by the EPA and other regula¬tory agencies have been based, reviewed new findings that have emerged since the EPA defined its current reference dose in 1995, and met with researchers of major on¬going population studies.
WHO Assesses World’s Health Systems
he World Health Organization has conducted its first-ever analysis of the worlds health systems, using five performance indicators to measure systems in 191 member states. The findings are published in The World Health Report 2000—Health Systems: Improving Performance.
The US spends a higher portion of its gross domestic product on health than any other country but ranks 37 out of 191 countries in performance, according to the WHO analysis.
According to WHO Director-General Gro Harlem Brundtland, MD MPH, “The main message [of the WHO] report is that the health and well-being of people around the world depend critically on the performance of the health systems that serve them. Yet there is wide variation in performance, even among countries with similar levels of income and health expenditure. It is essential for decision-makers to understand the underlying reasons so that system performance, and hence the health of populations, can be improved.”
In releasing the report, Christopher J.L. Murray, MD DPhil, Director of WHO’s Global Programme on Evidence for Health Policy, noted, “Although significant progress has been achieved in past decades, virtually all countries are underutilizing the resources that are available to them. This leads to large numbers of preventable deaths and disabilities, unnecessary suffering, injustice, inequality and denial of an individual’s basic rights to health.”
The report shows that health system failures impact most severely on the world s poor. One key recommendation in the report is for countries to extend health insurance to as large a percentage of the population as possible.
WHOs analysis compares each country’s system to an estimated upper limit of what can be done with the level of resources available in that country. It also measures what each country’s system has accomplished in comparison with those of other countries. The assessment is based on five indicators: overall level of population health; health inequalities (or disparities); overall level of health system responsiveness (a combination of patient satisfaction and how well the system acts); distribution of responsiveness within the population (how well people of varying economic statuses find that they are served by the health system); and the distribution of the health system’s financial burden within the population (who pays the costs).