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New Lead Screening Guidelines From The Centers for Disease Control and Prevention: How Will They Affect Pediatricians?

1997; American Academy of Pediatrics; Volume: 100; Issue: 3 Linguagem: Inglês

10.1542/peds.100.3.384

1098-4275

Birt Harvey,

Trace Elements in Health

In October 1991, the Centers for Disease Control and Prevention (CDC) issued lead screening guidelines1 thatIn 1993, the American Academy of Pediatrics (AAP) published recommendations2 similar to those of the CDC. Both sets of recommendations were influenced by reports demonstrating adverse neuropsychologic effects from BLLs as low as 10 μg/dL34and by data from the second National Health and Nutrition Examination Survey (NHANES II), conducted 1976–1980, showing that 88% of 1- to 5-year-old children had BLLs ≥10 μg/dL.56Subsequent to publication of the 1991 CDC and 1993 AAP guidelines, data from a number of blood lead screening studies demonstrated marked variation in the prevalence of elevated BLLs.7-12Publication of data from these studies, many appearing in the February 1994 issue of this journal, resulted in a commentary in the same issue that questioned the appropriateness of the CDC screening and follow-up recommendations.13Variation in the prevalence of children with BLLs ≥10 μg/dL ranged from 71% in central Philadelphia9 and 28% in central Rochester8 to 3.6% in Chicago suburbs7 and 0.6% in Alaska Medicaid children.10 In the Chicago area study, 0.1% of children had a BLL ≥20 μg/dL, and in Alaska none had a BLL ≥11 μg/dL.Results of Phase I (1988–1991) of NHANES III, which were unavailable when the 1991 CDC guidelines were developed, showed a marked reduction in the geometric mean (GM) BLL of 1- to 5-year-old children compared with NHANES II.14 The GM BLL was now 3.6 μg/dL compared with 15 μg/dL just 12 years earlier. More recent data from Phase II of NHANES III (1991–1994) showed a continuation of this trend, with the GM BLL dropping to 2.7 μg/dL, a 50% decline from Phase I in prevalence of children with BLLs ≥10 μg/dL. Other encouraging information from Phase II is presented in the Table.15Despite the good news during 1991–1994, about 930 000 children still had BLLs ≥10 μg/dL and about 85 000 of these children, 1 of every 250 1- to 5-year-olds, had BLLs ≥20 μg/dL.15Stratification of NHANES III data demonstrates marked variation among certain groups, with higher BLLs among non-Hispanic black and Mexican-American children and among children living in low-income families as well as those living in large metropolitan areas and in housing built before 1946.15In a 1994 AAP member survey, 65% of responding urban pediatricians and 40% of suburban and rural pediatricians replied that they attempted to follow CDC and AAP guidelines by screening their patients less than 36 months of age.16 Thus, pediatricians—based on the results of screening their patients, on knowledge of the literature, or on intuition—recognized that elevated BLLs were more prevalent in urban areas and less prevalent in suburbs. A CDC telephone survey found, however, that only 24% of parents reported that their young children had been screened.17 Thus, both surveys showed that many children in high-risk groups, primarily in central cities, still are not being screened.Both the CDC and the AAP are responding to the decreasing prevalence of elevated BLLs, to information about populations still at high-risk as noted in NHANES III and in many local and state surveys, and perhaps to the reluctance among pediatricians and other physicians to screen universally. The AAP Committee on Environmental Health is drafting new screening recommendations, whereas the CDC, with input from its Lead Poisoning Prevention Committee and from others, will release new screening guidelines shortly.18The objective of the 1997 CDC guidelines is maximum screening of children at high-risk and reduced screening of children at low-risk. With the removal of lead from gasoline and from food, lead in paint manufactured before it was essentially banned in 1978 remains the major source contaminating the environment of children. Children living in housing built before 1950 are at greatest risk because indoor paint in use until the late 1940s often contained up to 50% lead by weight.1 Exposure to other lead sources—eg, industrial waste, parental hobbies, folk remedies—tends to be limited to particular groups or to individual children.At the risk of oversimplifying a set of detailed and complex screening guidelines and follow-up recommendations, the following is presented as a summary of the thrust of the new CDC guidelines.18State and local health departments, working in conjunction with concerned groups, can and should develop new recommendations that will replace universal screening by focusing on children at highest risk. This will be accomplished by testing all children who live in certain circumscribed areas, defined by age of housing or by prevalence of elevated BLLs, and by testing any individual child who does not live in such an area, but who may be at risk for an elevated BLL.Screening of all children is recommended in:State health authorities will be responsible for determining which areas meet these criteria. An area could be as broad as a whole state or as narrow as an individual city block; most of the CDC discussion refers to zip codes and occasionally to census tracts.For children not residing in an area for which areawide screening is recommended, screening of individual at-risk children is proposed. Criteria for risk would be determined, again, by state health authorities or would be delegated to more local health personnel. Possible candidates for individual screening include:Management recommendations include:The 1997 guidelines emphasize that decisions are best made at the local level, that primary prevention should be foremost, and that representatives from a variety of concerned groups, eg, pediatricians, should be consulted during state and local policy development.These recommendations represent a marked improvement over the 1991 guidelines. They should result in increased attention and resources being focused on children at high-risk. Screening and follow-up of those most in need should be enhanced, and inappropriate dissipation of the time and energy of pediatricians, health department staffs, and parents should be diminished.The new CDC management recommendations for children found to have BLLs <20 μg/dL are appropriate for our current level of scientific knowledge, but further studies are required to address the following questions.Projects addressing these and other questions must be performed so that most management recommendations for children with BLLs <20 μg/dL will have a scientific rather than an empiric basis of support. This does not mean that we should ignore BLLs between 10 μg/dL and 20 μg/dL in young children. We cannot be sure without knowing the source of lead exposure that BLLs <20 μg/dL will not rise to clinically significant levels or that other vulnerable children may not develop significantly elevated BLLs from the same source. Therefore, young children with BLLs ≥10 μg/dL should be followed, and a source of exposure sought, whether in the home or elsewhere. For a community, finding a significant number of children with BLLs ≥10 μg/dL is a signal for a public health effort to attempt to find and to eliminate community-wide sources of exposure.Pediatricians have important roles to play in managing individual patients and in community involvement.Pediatricians should not make decisions on whom to screen based on anecdotal or personal experience but rather should follow state and locally developed policies. They can determine whether young children for whom they provide care live in a high-risk area in which all children should be screened. For children not residing in high-risk areas, pediatricians can determine whether a risk factor necessitating a BLL test exists. Unless modified by future studies, follow-up on children with a BLL ≥10 μg/dL should be based on CDC recommendations.Most important is the activity in which pediatricians excel, primary prevention. For example, if deposition of lead in bones is prevented, future leaching into the blood and elsewhere in the body will be prevented. If primary prevention is successful, monitoring or treating children with elevated BLLs is avoided.For all families of young children—and for pregnant women, if possible—pediatricians can offer anticipatory guidance. Families should be given information that will help them avoid sources of lead such as renovation of old houses, deterioration of paint in older houses, lead-containing materials from parental occupations or hobbies, or cultural sources of exposure. This information can be tailored to the community and to the population receiving guidance. During the process of providing information, pediatricians can assess whether substantial lead exposure already exists.Community involvement as recommended in the 1997 CDC guidelines may occur in several ways. Because risk factors will vary among communities, pediatricians have a role in working with state and local health authorities—who have data about local BLLs, housing age, and housing condition—to identify communities that may require areawide screening, to define local risks, to develop questionnaires or other instruments appropriate for the area, and to develop strategies to prevent lead poisoning. Pediatricians who participate in managed care organizations can recommend that such organizations follow CDC guidelines.Individual pediatricians can share in ongoing activities intended to prevent lead poisoning. The primary responsibility falls, however, on the CDC to develop and implement national policy recommendations and on state and local authorities working in conjunction with physician organizations, health maintenance organizations, and interested community groups to implement these recommendations at the state and local level.Implementation activities by state and local authorities should identify and control exposure sources, enforce housing codes, provide community education, collect screening data, provide environmental investigation services, and perform community surveillance.The CDC should perform or fund studies designed to answer questions such as those raised in this commentary regarding the effectiveness of interventions in children with BLLs <20 μg/dL and should continue to support the development of more rapid, easier, more accurate, and less expensive lead testing methods, both in blood and in environmental lead sources.Because anticipatory guidance time during office visits is limited, the AAP and other physician organizations should hasten the development of educational material that physicians can provide to families and should continue to include lead poisoning information in physician education programs. AAP chapter leaders should start meeting with state and local public health officials to begin development of state and local screening policies.As the 1997 CDC guidelines recommend, we should put our efforts and resources into screening high-risk children, into treating children who are most likely to show a significant response, and into primary lead poisoning prevention activities, especially treating deteriorating older housing and educating the public about exposure sources. Activities that remove lead from any source in the environment are worthwhile because environmental contamination results in increased lead in children, and only negative effects accrue. Nevertheless, because sociodemographic factors are stronger predictors of a child's cognitive development than are low BLLs, we should attempt to direct limited resources toward nonlead-related programs such as expanded support for child care, better child abuse prevention, and health care coverage of uninsured children, as well as toward programs eliminating lead from the environments of children. All are likely to have a greater effect on cognition than blood lead testing of low-risk children.With the elimination of lead from gasoline, food containers, and paint, the major products depositing lead in children's environments are gone, and the average BLL of children continues to decline. Lead paint remains in millions of older homes, but with the ongoing elimination of such homes and increasing emphasis on modification of others, lead in homes should gradually diminish. Although we still have almost 100 000 children under age 6 with BLLs ≥20 μg/dL, let us hope that in another 10 to 15 years lead poisoning in children will be an infrequent problem, primarily limited to a few children exposed to lead in uncommon ways. We will still need to remain vigilant, to work with public health personnel, and to provide anticipatory guidance, but we can hope that the need for frequent BLL determinations may become a memory.