Lead poisoning: low rates of screening and high prevalence among children seen in inner-city emergency departments

Screening children for elevated blood lead - learnings from the literature

INTRODUCTION

Although it is important that children at risk of developing elevated blood lead receive regular screening, attendance at screening programs is variable. A literature review was undertaken to better understand the factors that affect carers' decisions about whether or not to take their children for blood lead screening.

METHOD

Electronic databases (Medline, EMBASE, CINAHL, Psychinfo) were searched to identify relevant publications, supported by reviewing reference lists of identified articles and searching with internet-based search engines.

RESULTS

Thirty-four published studies dealing with blood lead screening rates were identified, of which only seven papers focused specifically on parent's attitudes to blood lead screening. The barriers to and enablers of screening for elevated blood lead levels appear to be similar to those identified for other screening programs.

DISCUSSION

It is recommended that attendance at screening be routinely monitored, and that where participation is suboptimal further research be undertaken, in close co-operation with affected communities or sub-groups, to determine how best to encourage screening and to protect children from lead. It is important to minimize stigma and to ensure, as far as possible, that practical barriers such as lack of transport do not restrict access to screening programs.

Blood lead screening

To evaluate local procedures for and barriers to testing Medicaid patients for lead toxicity, a retrospective review of 675 charts of Medicaid patients' age 12 to 36 months form the 7 practices who serve the vast majority of Medicaid children in Kalamazoo, Michigan was undertaken. We identified and tested a model for barriers to patients and physicians obtaining blood lead levels. Only 27.6% had blood lead levels substantially lower than the universal testing mandated by the Centers for Medicare and Medicaid Services. Physicians overestimated the number of children having blood lead tests, even with adjusting for patient non-compliance. Practices varied sharply in their approach to screening. Of 489 patients without findable lead test results, 139 (28.4%) were attributable to previous screening, 98 (20.0%) to patient failure, 181 (37.0%) to physician failure, 52 (10.6%) to patient + physician failure and 19 (3.9%) were indeterminate. There is need for improvement, standardization and unification of lead screening guidelines. Understanding barriers to blood lead testing is also necessary to develop credible data to promote shifts in public policy regarding lead abatement. Further studies should be done, such as interviews and questionnaires to determine why physicians fail to order blood lead tests, and patients fail to appear for a test that has been ordered.

In utero exposure to lead and cord blood total IgE. Is there a connection?

BACKGROUND

Lead exposure and total immunoglobulin E (IgE) have been shown to be positively related in animals and humans even at lead levels below those recognized as toxic. In the last decades, exposure to lead has become more frequent in urban areas of industrialized as well as of developing countries where IgE-mediated allergy prevalence has also increased.

METHODS

We examined for the first time the relationship between in utero exposure to lead and cord blood total IgE in two samples of 137 and 237 mother-newborn pairs, respectively, recruited in Paris.

RESULTS

Cord blood IgE was positively related to hair lead level at birth, providing an integrated measure of long-term exposure in utero, in each cohort (Spearman's coefficient r = 0.32, P < 0.001 and r = 0.19, P < 0.01, respectively) and in the combined cohort (r = 0.21; P < 0.01). The relationship appeared to be more pronounced in newborns of nonallergic mothers (r = 0.24; P < 0.01) than in those of allergic mothers (r = 0.12). This could be due to the fact that familial history of allergy, the strongest determinant of IgE development, may overshadow the influence of lead on IgE in the offspring.

CONCLUSIONS

Our findings suggest a possible intervention of environmental exposure besides genetic factors in early life development of IgE production. Further studies are needed to confirm the finding.

Smoking in parents of children with asthma and bronchiolitis in a pediatric emergency department

OBJECTIVES

To determine smoking habits, levels of nicotine-addiction, readiness to quit, and beliefs about the effects of environmental tobacco smoke (ETS) of parents of children with bronchiolitis and asthma who present to a children's emergency department (ED).

DESIGN/METHODS

This was a cross-sectional prevalence study of parents or legal guardians of children with asthma or bronchiolitis presenting to a pediatric ED.

RESULTS

Two hundred forty-nine parents/legal guardians comprised the study group. The mean age (+/-SD) was 30.0 (+/-8.9) years; 88% were female; 51% were nonwhite; 37% were educated beyond high school. The self-reported smoking prevalence was 41% (95% CI = 32-51). Smoking prevalence among parents of wheezing children varied according to education, income, and race, but not according to gender, age, or employment status. Of the 102 smokers in the sample, 84 (82.4%, 95% CI = 73-88) reported that they wanted to quit; 78 (76.5%, 95% CI = 68-84) stated that they wanted to quit within the next month. Forty-nine percent (95% CI = 39-59) scored above 4 on the Fagerstrom Test for Nicotine Dependence and were considered nicotine-dependent. The majority of smokers admitted to smoking around their children (66.7%, 95% CI = 57-75). Many parents knew that ETS might contribute to the development of the following illnesses: colds/upper respiratory tract infections - 77.5%, otitis media - 68.6%, pneumonia - 50%, wheezing/asthma attacks - 86.3%, and SIDS - 31.4%.

CONCLUSION

The prevalence of smoking and nicotine addiction among parents of children with asthma or bronchiolitis who bring their children to a pediatric ED is high. Many parents have some knowledge about the effects of ETS, and the majority would like to quit. Future studies to help determine the best way to deliver advice to parents on ETS exposure reduction and smoking cessation are warranted.

Screening for Elevated Blood Lead Levels

Although recent data continue to demonstrate a decline in the prevalence of elevated blood lead levels (BLLs) in children, lead remains a common, preventable, environmental health threat. Because recent epidemiologic data have shown that lead exposure is still common in certain communities in the United States, the Centers for Disease Control and Prevention recently issued new guidelines endorsing universal screening in areas with ≥27% of housing built before 1950 and in populations in which the percentage of 1- and 2-year-olds with elevated BLLs is ≥12%. For children living in other areas, the Centers for Disease Control and Prevention recommends targeted screening based on risk-assessment during specified pediatric visits. In this statement, The American Academy of Pediatrics supports these new guidelines and provides an update on screening for elevated BLLs. The American Academy of Pediatrics recommends that pediatricians continue to provide anticipatory guidance to parents in an effort to prevent lead exposure (primary prevention). Additionally, pediatricians should increase their efforts to screen children at risk for lead exposure to find those with elevated BLLs (secondary prevention).

Statewide assessment of lead poisoning and exposure risk among children receiving Medicaid services in Alaska

OBJECTIVE

Lead poisoning is a well-recognized public health concern for children living in the United States. In 1992, Health Care Financing Administration (HCFA) regulations required lead poisoning risk assessment and blood lead testing for all Medicaid-enrolled children ages 6 months to 6 years. This study estimated the prevalence of blood lead levels (BLLs) >/=10 microg/dL (>/=0.48 micromol/L) and the performance of risk assessment questions among children receiving Medicaid services in Alaska.

DESIGN

Measurement of venous BLLs in a statewide sample of children and risk assessment using a questionnaire modified from HCFA sample questions.

SETTING

Eight urban areas and 25 rural villages throughout Alaska.

PATIENTS

Nine hundred sixty-seven children enrolled in Medicaid, representing a 6% sample of 6-month- to 6-year-old Alaska children enrolled in Medicaid.

OUTCOME MEASURE(S)

Determination of BLL and responses to verbal-risk assessment questions.

RESULTS

BLLs ranged from <1 microg/dL (<0.048 micromol/L) to 21 microg/dL (1.01 micromol/L) (median, 2.0 microg/dL or 0.096 micromol/L). The geometric mean BLLs for rural and urban children were 2.2 microg/dL (0.106 micromol/L) and 1.5 microg/dL (0.072 micromol/L), respectively. Six (0.6%) children had a BLL >/=10 microg/dL; only one child had a BLL >/=10 microg/dL (11 microg/dL or 0.53 micromol/L) on retesting. Children whose parents responded positively to at least one risk factor question were more likely to have a BLL >/=10 microg/dL (prevalence ratio = 3.1; 95% confidence interval = 0.4 to 26.6); the predictive value of a positive response was <1%.

CONCLUSIONS

In this population, the prevalence of lead exposure was very low (0.6%); only one child tested (0.1%) maintained a BLL >/=10 microg/dL on confirmatory testing; no children were identified who needed individual medical or environmental management for lead exposure. Universal lead screening for Medicaid-enrolled children is not an effective use of public health resources in Alaska. Our findings identify an example of the importance in considering local and regional differences when formulating screening recommendations and regulations, and continually reevaluating the usefulness of federal regulations.

Census tract analysis of lead exposure in Rhode Island children

There has been increasing interest in a targeted approach to the screening and prevention of lead exposure in children. Targeted screening requires an understanding of variation in lead exposure in individual children or by region. In order to better understand variation by region, we studied Rhode Island lead poisoning screening data, examining average lead exposure to children living in 136 Providence County census tracts (CTs). The study population included 17,956 children aged 59 months and under, who were screened between May 1, 1992, and April 30, 1993. We evaluated the relationship between the percentage of children with blood lead > or = 10 micrograms/dL (pe10) and sociodemographic and housing characteristics, derived from United States 1990 Census data, of these CTs. CT descriptors included population density, percentage of households receiving public assistance income, median per capita income, percentage of households female headed, percentage of houses owner occupied, percentage of houses built before 1950, percentage of houses vacant, percentage of population Black, percentage of recent immigrants, and intraurban mobility. On average, 109 children were screened in each census tract; mean screening rate was 44%. There was wide variation in average lead exposure among census tracts, with pe10 ranging from 3 to 60% of screened children (mean 27%). Individual census variables explained between 24 and 67% of the variance in pe10 among CTs. A multiple regression model including percentage screened, percentage of households receiving public assistance, percentage of houses built before 1950, In (percentage of houses vacant), and percentage of recent immigrants explained 83% of variance in pe10. The percentage of houses built before 1950, a variable which models the presence of lead paint in old houses, displayed the largest adjusted effect on pe10 over the range observed for that variable in RI CTs. The percentage of houses vacant was also a highly significant and robust predictor; we suggest that vacancy is an ecological marker for the deterioration of leadbased paint, with higher vacancy neighborhoods containing houses in poorer condition. In Rhode Island, census tracts with high vacancy rates also have high rates of recent immigration, making immigrant groups vulnerable to lead exposure. Small-areas analysis may be useful in directing resources to high risk areas, explaining the sociocultural forces which produce such exposure and analyzing the effects of housing policy over time in states with high screening penetration.