Blood Lead Levels Among Children -- Rhode Island, 1993-1995

Since January 1993, screening of children aged less than 6 years for elevated blood lead levels (BLLs) has been mandatory in Rhode Island. * Erythrocyte protoporphyrin was eliminated as a method of lead screening in February 1993; since then, all children in the state have been screened for lead poisoning by testing capillary or venous blood samples for lead. From March 1993 through February 1995, results of blood lead tests of 56,379 children aged less than 6 years were reported to Rhode Island's lead surveillance system. This report summarizes an analysis of these data by the Rhode Island Department of Health (RIDH) to better characterize the burden of childhood lead poisoning in the state.

In Rhode Island, recommendations for screening children aged less than 6 years adhere to CDC's guidelines (1) and are based on a child's risk for lead poisoning and the results of previous blood lead tests. In a previous analysis through September 1994 (2), 99% of all children born in Rhode Island during September 1990-August 1991 had at least one BLL recorded in the RIDH screening database. For children who were tested from March 1993 through February 1995, age, sex, and socioeconomic status were reported for greater than 97%, and race/ethnicity was reported for 86%. Race/ethnicity is presented in this report because it is a risk factor for elevated BLLs independent of socioeconomic status (3). Venous screening samples were obtained from 10,717 (33%) children screened during March 1993-February 1994 (year 1), and from 11,403 (47%) children screened during March 1994-February 1995 (year 2). These data represent initial screens and do not include follow-up tests. Because capillary samples sometimes may be contaminated with lead dust from incompletely cleaned fingers, resulting in an overestimate of BLLs, this report presents results for the analysis of venous samples only.

From year 1 to year 2, the overall percentage of children with elevated BLLs (greater than or equal to 10 ug/dL) among all age groups declined Table_1. However, the percentage of children with very high BLLs (i.e., greater than or equal to 45 ug/dL) was similar for the 2 years. For both years, most children with BLLs greater than or equal to 10 ug/dL lived in poverty ** (66.9%) and were members of racial/ethnic minority groups (63.5%).

From year 1 to year 2, the geometric mean BLL declined from 5.4 ug/dL to 4.1 ug/dL Table_2. Declines occurred in all racial/ethnic, socioeconomic, and age groups. However, the mean BLL was higher for children who were members of racial/ethnic minority groups and for those living in poverty. In particular, children with BLLs greater than or equal to 20 ug/dL disproportionately included Hispanics (35% and 33% for years 1 and 2, respectively), who constituted 4.6% of the total population of Rhode Island, blacks (24% and 29%), who constituted 3.9% of the population, and Asian/Pacific Islanders (11% and 7%), who constituted 1.8% of the state's population. In both years, the highest mean BLLs occurred among children aged 2 years.

Reported by: B Matyas, MD, P Simon, MD, W Dundulis, MS, R Vanderslice, PhD, L Boulay, MS, Rhode Island Dept of Health. Surveillance and Programs Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health; Div of Field Epidemiology, Epidemiology Program Office; CDC.

Editorial Note

Editorial Note: The findings in this report indicate that, although BLLs were elevated among high proportions of children in Rhode Island, overall mean BLLs and the prevalence of elevated BLLs among children receiving initial venous tests declined during 1993-1995. These declines may have reflected the effect of 1) sampling (i.e., targeting of children at high risk for lead poisoning in year 1 may have resulted in fewer at-risk children undergoing initial testing in the second year); 2) a change in the pattern of use of venous versus capillary methods for initial tests of high-risk children; 3) prevention activities, which may have decreased the number of children exposed to lead hazards; and/or 4) decreases unrelated to current prevention activities.

The patterns of elevated BLLs in Rhode Island are similar to those in the Third National Health and Nutrition Examination Survey (NHANES III) (3): BLLs were highest among racial/ethnic minority children and children living in poverty. Despite declines in BLLs in Rhode Island, the persistent high prevalence of elevated BLLs indicates the need for continued screening and prevention activities in the state. The Rhode Island lead surveillance data will assist in ongoing evaluation of the effectiveness of RIDH's intervention and prevention efforts. The Rhode Island lead program provides environmental inspections of homes of children with elevated BLLs, nutritional information, education about approaches to reducing lead exposure to families of children with elevated BLLs, educational materials to the general public and health professionals, funds for the primary lead poisoning treatment clinic in the state, and financial assistance for lead inspection and abatement.

Surveillance for BLLs enables the monitoring of trends and distributions of BLLs among young children. In May 1995, the Council of State and Territorial Epidemiologists added elevated BLLs among children and adults to the National Notifiable Diseases Surveillance System. CDC is collaborating with 24 states to develop laboratory-based surveillance for BLLs among children, which can be used to target resources and assess the effectiveness of intervention efforts.

References

1. CDC. Preventing lead poisoning in young children: a statement by the Centers for Disease Control, October 1991. Atlanta: US Department of Health and Human Services, Public Health Service, 1991.

2. Buchner J, Simon P, Dundulis W, et al. Health by numbers: lead poisoning among Rhode Island preschoolers. Rhode Island Medicine 1995;4:120.

3. Brody DJ, Pirkle JA, Kramer RA, et al. Blood lead levels in the U.S. population: phase 1 of the Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1991). JAMA 1994;272:277-83.

* Rhode Island Rules and Regulations for Lead Poisoning Prevention (R23-24.6-PB) section A.2.3 as amended.

** As determined by the Bureau of the Census, which designates the socioeconomic status of every census tract in the United States.

TABLE 1. Distribution of venous blood lead levels (BLLs) * among children aged <6 years, by age group at testing and year -- Rhode
Island Childhood Lead Surveillance Program, March 1993-February 1994 (year 1) and March
1994-February 1995 (year 2)
========================================================================================================================================

                                                        Age Group (years)
         -------------------------------------------------------------------------------------------------------------------------------
               <1 year                1-2 years               3-5 years              Unknown @                Total
         --------------------   ---------------------    --------------------    --------------------   ---------------------
          Year 1 +    Year 2 &    Year 1      Year 2       Year 1     Year 2      Year 1      Year 2      Year 1      Year 2
BLL      --------   ---------   ---------   ---------    ---------  ---------    --------    --------   ---------   ---------
(ug/dL)  No.  (%)    No.  (%)    No.  (%)    No.  (%)     No.  (%)   No.  (%)    No.  (%)    No.  (%)    No.  (%)    No.  (%)
----------------------------------------------------------------------------------------------------------------------------------------
<10      946 (88)   1321 (92)   3357 (74)   4168 (84)    3576 (74)  4103 (85)    212 (79)    139 (87)   8091 (76)   9731 (85)
>=10     129 (12)    116 ( 8)   1176 (26)    794 (16)    1266 (26)   742 (15)     55 (21)     20 (13)   2626 (25)   1672 (15)
>=15      54 ( 5)     46 ( 3)    535 (12)    374 ( 7)     522 (11)   282 ( 6)     20 ( 8)      6 ( 4)   1131 (11)    708 ( 6)
>=20      24 ( 2)     19 ( 1)    252 ( 6)    188 ( 4)     239 ( 5)   119 ( 3)      7 ( 3)      3 ( 2)    522 ( 5)    329 ( 3)
>=45       1 (<1)      1 (<1)     12 (<1)     12 (<1)       3 (<1)     5 (<1)      0           0          16 (<1)     18 (<1)

Total   1075        1437        4533        4962         4842       4845         267         159      10,717      11,403
----------------------------------------------------------------------------------------------------------------------------------------
* Data represent initial screens and do not include follow-up tests.
+ Age missing for 267 children.
& Age missing for 159 children.
@ Age <72 months, but specific age subset unknown.
========================================================================================================================================

TABLE 2. Geometric mean venous blood lead levels (BLLs) * among children aged <6
years, by age, race/ethnicity, socioeconomic status, and year, and percentage
change from year 1 to year 2 -- Rhode Island Lead Surveillance Program, March
1993-February 1994 (year 1) and March 1994-February 1995 (year 2)
======================================================================================
                               Year 1              Year 2
                         -----------------   -----------------
                                 Geometric           Geometric    % Change
                           No.   mean BLL      No.   mean BLL     from year 1
Characterisitic          tested   (ug/dL)    tested  (ug/dL)       to year 2
--------------------------------------------------------------------------------------
Age (years)
  <1                      1075     4.5        1437     3.4           -24
   1                      2331     5.3        3142     3.8           -28
   2                      2202     5.9        1820     4.7           -20
   3                      2080     5.6        1819     4.4           -21
   4                      1671     5.6        1679     4.3           -23
   5                      1091     5.4        1347     4.0           -26
  Unknown                  267     5.1         159     4.0           -22

Race/Ethnicity
   White, non-Hispanic    5439     4.4        6388     3.3           -25
   Black, non-Hispanic     894     8.3         866     7.0           -16
   Hispanic               2412     7.1        2000     5.6           -21
   Asian/Pacific
    Islander               586     8.2         389     6.9           -16
   American Indian/
    Alaskan native          25     9.3          13     7.4           -20
   Other                   129     6.0         154     4.4           -27
   Unknown                1232     5.0        1593     4.2           -16

Socioeconomic
 status +
  Poverty                 4354     7.7        3987     6.3           -18
  Low                     1401     4.7        1709     3.5           -26
  Middle                  3658     4.1        4349     3.1           -24
  High                    1096     4.2        1133     3.0           -29
  Unknown                  208     4.3         225     3.6           -16

Total                   10,717     5.4      11,403     4.1           -24
--------------------------------------------------------------------------------------
* Data represent initial screens and do not include follow-up tests.
+ As determined by the Bureau of the Census, which designates the socioeconomic
  status of every census tract in the United States.
======================================================================================

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