Levels of Hg, Pb and V in brain, kidney, liver and lung of anencephalic fetuses from the Eastern coast of Lake Maracaibo, Venezuela

This work describes the levels of mercury (Hg), lead (Pb) and vanadium (V) in brain, kidney, liver and lung of anencephalic (A) and control (C) fetuses from the Eastern coast of Lake Maracaibo (Venezuela) evaluated from April 1993 to July 1994. A relatively high anencephaly rate of 5.1 per 1,000 total births was reported in this area for 1994. A petroleum empire has grown indiscriminately in the region under study, provoking adverse effects in the environment and in humans due to the constant release of these toxicants. Sample analyses were done by cold vapour atomic absorption spectrometry (for Hg), differential pulse anodic stripping voltammetry (for Pb) and electrothermal atomization atomic absorption spectrometry (for V). Twenty stillborn fetuses with anencephaly (mean gestation age 34.4 weeks, range 20 - 40 weeks) and 20 stillborn fetuses without anencephaly (mean gestation age 38.5 weeks, range 36 - 40 weeks), included as controls, were considered for the present study. All births occurred at Pedro Garcia Clara Hospital, a public health care center of Ciudad Ojeda (Lagunilla county). Before the spectrometric and voltammetric determinations, samples were mineralized by microwave heating in high-pressure reactors. For all metals, precision (RSD) was better than 5.3%, for both within- and between-run (day-to-day) analyses, which can be considered adequate for these types of analytical evaluations of real samples. Accuracy was tested by analyzing 4 standard reference materials, supplied by 2 international agencies. The dry-weight metal concentrations (mean + 1 SD, μg/g) found in brain, kidney, liver and lung were as follows : Hg (brain, 0.07 ± 0.01 in A, undetectable in C ; kidney, 0.29 ± 0.05 in A, 0.07 ± 0.03 in C ; liver, 0.33 ± 0.03 in A, 0.17 ± 0.08 in C ; lung, 0.45 ± 0.40 in A, 0.12 ± 0.01 in C) ; Pb (brain, undetectable in A and in C ; kidney, 1.9 ± 0.3 in A, 0.7 ± 0.3 in C ; liver, 2.1 ± 0.3 in A, 1.1 ± 0.5 in C ; lung, 3.3 ± 0.4 in A, 0.5 ± 0.1 in C) ; V (brain, 0.25 ± 0.18 in A, 0.64 ± 0.28 in C). Mercury and Pb were significantly increased (p < 0.001) in kidney and liver of anencephalic fetuses. Vanadium was detected exclusively at brain level, being significantly higher in controls (p < 0.05). Hence, V seems to be the most unlikely of the 3 elements studied to be associated with anencephaly. In conclusion, Hg and Pb are toxic elements present in the Eastern coast's environment that should be seriously considered for cause/effect studies when the etiology of anencephaly in this region is considered. However, this malformation is multifactorial and, thus, a more complete study must be carried out in order to be able to reach conclusive ideas, if this is possible. Meanwhile, anencephaly will continue to be a puzzling disease.