Elements in human placentae in Jamaica

To investigate the relationships, if any, between elemental content of the placenta with age of mother birthweight and the Apgar scores of a neonate.

Placental samples were collected, stored at -20 degrees C and then dried and analysed using neutron activation with the SLOWPOKE II reactor at the International Centre for Environmental and Nuclear Sciences (ICENS). A questionnaire was administered at the time of delivery to determine the level of fish consumption, numbers of dental amalgam fillings and use of cough syrups. Placental concentrations of bromine, calcium, chlorine, iron, mercury, potassium, rubidium, selenium, sodium and zinc were determined.

The placentae of 52 Jamaican mothers with a mean age 29 years (range 18-42 years) delivering singleton neonates with a mean birthweight of 3.1 kg (1.3-5.5 kg) at term were collected. With the exception of iron and bromine, all results for elemental determinations are very similar to those found elsewhere. Correlation was observed for Apgar 2 (5 minutes), calcium and zinc with birthweight, with p-values of 0.002, 0.007 and 0.07, respectively. Negative correlation was observed for the Apgar 2 and potassium (p = 0.056) and age of mother at birth and bromine (p = 0.02). The mercury concentration in the measured placentae (7.29 +/- 9.1 microg/kg w/w) was slightly lower than the mean concentration found in the literature (8 microg/kg w/w). Approximately 93% of the measured placentae in this study are below the derived placentae upper limit of 22 microg/kg. Of the 7% above the upper limit none exceeded the conservative estimated limit of 115 microg/kg at which neural developmental problems start.

The significant associations noted are of unknown clinical relevance and need further study.