(Beyond Pesticides, November 7, 2012) Pregnant beluga whales pass to their fetus a portion of the persistent organic pollutants, PCBs and flame retardants, they carry in their bodies, report researchers who measured the chemicals in the animals’ blubber. The study is one of the first to show whales, like people, can transfer and expose their developing offspring to persistent contaminants, whose long-term health effects continue to remain unclear.
A study of Arctic beluga whales (Delphinapterus leucas) confirms that mothers can pass more than a tenth of their chemical burden of PBDE flame retardants and PCBs to their unborn calves. This study found that the mother whales transferred, on average, 11.4% (7.5â€‰mg) and 11.1% (0.1â€‰mg) of their polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) blubber burden to their near-term fetuses. Mammals transfer contaminants, usually persistent organic pollutants (POPs), during pregnancy to the developing fetus and during lactation when the baby is nursing. Lactation transfer has been well studied in marine mammals, but very little is known about the transfer of pollutants during pregnancy. POPs are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they have been observed to persist in the environment, to be capable of long-range transport, bioaccumulate in human and animal tissue, biomagnify in food chains, and to have potential significant impacts on wildlife and human health.
Previous reports have documented toxic chemicals in the brains of marine mammals and identified several contaminants including organochlorine pesticides like DDT, PCBs and flame retardants in the cerebrospinal fluid and cerebellum gray matter of several species of marine mammals including the short-beaked common dolphins, Atlantic white-sided dolphins and the gray seal. PCBs have been found in alarmingly high concentrations. Researchers also found low levels of PCBs in the cerebrospinal fluid of a gray seal. The antibacterial triclosan has also been detected in the in the blood of bottlenose dolphins.
This new study is unique because it examines blubber from healthy pregnant whales. Previously most research has investigated beached or ill whales. This study is only the second to report mother to fetus transfer of PBDE flame retardants in whales. The study is also important because it focuses specifically on the amount of chemicals transferred to the fetus during pregnancy. Chemical exposure during critical times of gestation is known to cause abnormal growth and development. In some instances, prenatal exposures can impact health in adults many years later. Both classes of chemicals measured in the study are persistent and accumulate in animals at the top of the food chain.
As for humans, the Centers for Disease Control (CDC) published the first study to look at a broad range of chemicals specifically in pregnant women which analyzed biomonitoring data to characterize both individual and multiple chemical exposures in U.S. pregnant women. Researchers analyzed the data for 163 chemicals and detected about three-quarters of them at varying levels in some or all of the women. They found almost all â€“ 99 to 100 percent â€“ of the pregnant women carry PCBs, organochlorine pesticides, perfluorinated compounds, phenols such as triclosan, PBDEs, phthalates, polycyclic aromatic hydrocarbons (PAHs) and perchlorate.
Various studies have reported that prenatal exposure to chemical pollutants, like PCBs, PBDEs and pesticides can negatively impact the developing fetus. One study reports that the antibacterial pesticide, triclosan, has a high potency to act as an inhibitor of estrogen sulfotransferase activity raising concerns about its possible effects on the ability of the placenta to supply estrogen to the fetus. Another found significant associations of prenatal pesticide exposure with structural changes in the developing human brain, and also may affect both length of pregnancy and birth weight.
These findings further understanding of potential risks associated with chemical exposures to the developing fetus before birth and nursing begins. In mammals, hormones direct critical physical and mental development during gestation. The fetus is vulnerable to chemicals that can alter hormones â€“ generally called endocrine-disrupting chemicals. Both the PCBs and PBDEs targeted in the study can disrupt hormone functions. PCBs, PBDEs and various pesticides are known to cause a diverse range of health effects, including cancer, immune system problems and thyroid diseases. In addition, early exposure to PCBs has been linked to cardiac diseases in animals. Even though PCBs have been banned and PBDEs restricted they are still routinely detected in the environment, people and wildlife. In the environment, PCBs, PBDEs, and other persistent organic pollutants breakdown very slowly and can travel long distances, accumulating in wildlife, people and remote locations such as the Arctic.
The study illustrates that the health impacts of pesticides are often subtle and delayed, and that pesticides once considered to pose â€śacceptableâ€ť risks are continuing to affect public health years after being pulled from the market. In response to the growing evidence linking pesticide exposures to numerous human health effects, Beyond Pesticides launched the Pesticide-Induced Diseases Database, to capture the range of diseases linked to pesticides through epidemiologic studies. The database, which currently contains hundreds of entries of epidemiologic and laboratory exposure studies will be continually updated to track the emerging findings and trends.
Source: Environmental Health News
All unattributed positions and opinions in this piece are those of Beyond Pesticides.