Page 83 - Encyclopedia of Nursing Research

50 n CHILDBIRTH EDUCATIon

conflicting results were common, lead expo- concentrations. Research with lead-exposed
sure and neurobehavioral deficits remained primates strengthened the consensus, and
C significantly associated. the toxic level of lead was redefined by the
The earliest studies of lead poisoning CDC as a BLL ≤ 10 μg/dl.
were conducted on children who had BLL Recently, nurse researchers have used
≥ 60 μg/dl and were symptomatic. During the Dixon’s Integrative Environmental Health
1970s, researchers focused on asymptomatic Model (Dixon & Dixon, 2002) to identify knowl-
children who had BLL in the range of 40 to 50 edge gaps related to public policy that have
μg/dl. Conclusions about the effects of lead prevented the development of effective strat-
exposure were difficult to make from these egies to create environmental lead- exposure
studies because of their methodological short- policy change (Perron & o’Grady, 2010).
comings. In 1979, researchers conducted a Researchers continue to study the effects
major investigation of large cohorts of asymp- of low-level lead exposure on the develop-
tomatic children and used shed deciduous ment of infants, children, and adolescents.
teeth rather than BLL to measure lead expo- Longitudinal studies involving large and
sure (needleman et al., 1979). These research- diverse populations that involve standard-
ers controlled for major confounding variables ized measurement and control of known
and concluded that BLL was associated with confounders will need to be undertaken.
lower IQ, decreased attention span, and poor Although these efforts are worthwhile,
speech and language skills in the children future efforts also could focus on (1) iden-
studied. Long-term follow-up of these chil- tifying mediators of lead exposure effects,
dren lead the researchers to conclude that the (2) investigating the effects of strategies to
effects of low-level lead exposure (equivalent lower BLLs (chelation and environmental lead
to BLL ≤ 25 μg/dl) persisted throughout young abatement) on the neurobehavioral outcomes
adulthood; failure to complete high school, of children, (3) investigating the synergistic
reading disabilities, and delinquency were effects of other environmental exposures on
behaviors exhibited by children who had ele- neurocognitive development, and (4) investi-
vated BLL at age 7 years (needleman, Riess, gating the effects of educational strategies to
Tobin, Biesecker, & Greenhouse, 1996). inform parents about preventing or reducing
Scientists criticized the work done by environmental lead exposure. Furthermore,
needleman et al. (1979) because the study investigations of the effectiveness of early
lacked baseline data about early cogni- intervention strategies for children identi-
tive abilities of the subjects. For instance, fied with elevated lead levels need to be con-
it was proposed that the affected children ducted. Any efforts that address the primary
may have had neurological deficits at birth prevention of the problem would help to
that would lead them to certain behaviors protect millions of children against the long-
(increased mouthing) that predisposed them lasting effects of lead exposure.
to be lead exposed. To address this issue,
subsequent studies were designed to follow Heidi V. Krowchuk
large numbers of subjects from birth through
early school age, and major outcomes
(e.g., IQ level, motor development, cogni-
tive development) were measured whereas Childbirth eduCation
large numbers of covariates were controlled.
numerous investigators using comparable
designs reported similar findings; thus, a Childbirth education focuses on the learn-
solid consensus among investigators began to ing needs of expectant families and covers a
emerge that lead was toxic at extremely low broad range of topics from the physical care