The early exposure to heavy metals can cause biological and clinical effects in the long term

25/01/2013

The early exposures to heavy metals, even at doses below those currently generally considered “safe”, can cause biological and clinical effects throughout life. This is the main conclusion of the study “Placental Concentrations of Heavy Metals in a mother-child cohort. Environmental Research “developed by INMA Project Investigators.

Human activity releases into the environment different toxic compounds that can be very harmful to human health and to most forms of life, including some heavy metals (including mercury). Therefore, last week 140 countries agreed on the “Minamata Convention” reduce environmental levels of mercury, by prohibiting their use in batteries, lamps, relays and cosmetics, as well as control their emissions in industrial plants (thermal, cement, chemical, etc.), from 2020. The treaty includes phasing out its use in dentistry although it is permitted as a preservative in vaccines and other devices provided there is no safe substitute.

Human activity releases into the environment different toxic
compounds that can be very harmful to human health and to most
forms of life, including some heavy metals (including mercury).

This is good news for Childhood and Environment Project. Remember that one of the objectives of the project is known INMA inadvertent exposure of children to toxic chemicals such as heavy metals and identify environmental factors that determine this exhibition. We are interested in studying how exposure during the first years of life, especially the womb, since exposure that occurs during this period of particular susceptibility develops in which the individual may be associated with adverse health effects that could occur at birth or later in life.

The INMA project observed that a high percentage of infants enrolled in the study have levels of mercury in cord blood larger than recommended by various international agencies. Thus, 24{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} of children exceeded the levels recommended by the FAO (WHO) and 64{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} proposed by the Environmental Protection Agency (EPA). Mercury is an environmental pollutant with ubiquitous distribution that comes from both natural sources and human activity. Diet is the main source of exposure in the general population. In fact, the levels found were associated clearly with the consumption of large predatory fish, such as swordfish or swordfish and bluefin tuna by the mother during pregnancy (Ramon et al., 2011). Just as the levels of mercury found in the hair of children at four years was associated with fish consumption (Freire et al., 2010).

Elaborating on this goal, the work led by Esperanza Amaya, from the cohort INMA-Granada, was to evaluate in utero exposure to mercury, other four heavy metals (manganese, cadmium, chromium and lead) and a metalloid (arsenic) in the placentas collected in the INMA-Granada cohort. Granada The cohort consists of a total of 700 pairs of mothers and their sons, born between October 2000 and August 2002 at the University Hospital San Cecilio of Granada. The child’s parents were informed of the study objectives and procedures to apply to participate, and to consent to an epidemiological questionnaire respondents consenting to the use of the necessary information from the medical history and the use of the placenta to study exposure levels of contaminants of interest. For this study randomly selected a fifth (n = 137) of the placentas of the cohort.

The INMA project and noted that a high percentage
of infants enrolled in the study have levels of mercury
in cord blood larger than recommended by various international agencies.

All placentas studied had detectable levels of cadmium and manganese while chromium, lead and mercury were found in 98.5{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b}, 35.0{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} and 30.7{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} of the samples, respectively. The mean concentrations found were high to low: 94.8 ng of lead / g dry weight of placenta, manganese 63.8 ng / g, 63.7 ng chromium / g, 3.45 ng cadmium / g and 0.024 mercury ng / g. The arsenic compound was not detected in any of the analyzed placentas.

None of the mothers stated occupations that may involve greater exposure to heavy metals investigated. Smoking during pregnancy and gestational age of the child were related to levels of cadmium found, while none of the characteristics of the mother or the child collected, was associated with concentrations of chromium, mercury, manganese, or lead. This time there was no information on diet during pregnancy so it could not be determined whether, as in previous work, this was the main source of general population exposure to these pollutants.

Having gathered much information about exposures
during pregnancy and the first years of life, we investigate
long-term effects of early exposures, which, although subtle,
allowing us to take preventive counseling attitudes and habits 

If we compare our results with the concentrations found in samples of placenta in other European studies, the levels of heavy metals found in placentas Spanish occupy the middle-low. However, studies conducted in other countries indicate that early exposures to heavy metals at doses below those currently generally considered “safe” can cause biological and clinical effects later in life. In addition, the reference levels for heavy metals have not been established in placenta samples.

The commitment of INMA is to continue to present and future in order to show that the Spanish general population of children inadvertently exposed to multiple chemicals that can cause adverse health effects. We value greatly the cohort tracking, having collected as much information about exposures during pregnancy and the first years of life, we can investigate long-term effects of early exposures, which, although subtle, allow us to take preventive counseling attitudes and habits lower risk in our society.
Article: Amaya E, Gil F, Freire C, Olmedo P, Fernández-Rodríguez M, Fernández MF, Olea N. Placental concentrations of heavy metals in a mother-child cohort. Environmental Research. 2013;120:63-70. doi: 10.1016/j.envres.2012.09.009.

* Esperanza Amaya holds a degree in Environmental Science and a researcher at the INMA cohort of Granada; in next to no time defend his doctoral thesis entitled: “Placental exposure to environmental contaminants in the study cohort INMA-Granada” 

* Marieta Fernández is a professor at the University of Granada and coordinator of the INMA cohort of Granada.