“Low levels of hexachlorobenzene (HCB) do not seem to affect the intrauterine growth or the duration of gestation”


Hexachlorobenzeneor (HCB) is an organochlorine compound formed as a byproduct during the manufacture of other chemicals. Formerly it had been widely used as a fungicide to control the fungal disease of wheat, but it is currently banned. Despite the broad restriction of its use, people can still be exposed to low levels of HCB through the food chain, as it bioaccumulates mainly in the fat tissue of animals where it can persist for years. HCB can cross the placenta and accumulate in the developing fetus, and it can also bioaccumulate in breast milk, due to its fatty properties.

Long-term, oral high-level exposure to HCB in humans has been associated with liver disease and skin lesions. Based on the results of animal experiments, it has been classified as a probable human carcinogen by the International Agency for Research on Cancer and the United States Environmental Protection Agency. However, the long-term health effects of background – very low – levels of exposure to HCB remain controversial. Several previous studies examined the potential effects of background level of HCB exposure during pregnancy and the developing fetus. About half of the studies found decreased birth weight and gestational length amongst newborns of women with higher level of blood HCB. Some of these studies suggested that the newborns of the mothers who had been smoking during pregnancy were more affected than those whose mothers did not smoke during this period. The other half of the studies, however, could not show any relationship between low-level exposure to HCB and impaired fetal development and preterm delivery.

In the current study Dr. Basterrechea, the leader investigator of the study, and his colleagues examined the potential effects of HCB exposure during the 1st trimester of pregnancy on the growth of the fetus and on the gestational age (which is the duration of the pregnancy). In total 1,568 mother-child pairs of the Infancia and Medioambiente (INMA) project were included in the study. Maternal blood levels of HCB were measured during the 1st trimester of pregnancy and data about body metrics of the newborns, such as birth weight and length and weeks of gestational age were also collected for each mother-child pair. Basterrechea and colleagues could not find any association between maternal HCB exposure and the growth of the fetus or the weeks of gestation.

The findings of this INMA study support the idea that exposure to low levels of HCB does not affect the intrauterine growth nor the duration of gestation.

REFERENCE: Basterrechea M, Lertxundi A, Iñiguez C, Mendez M, Murcia M, Mozo I, Goñi F, Grimalt J, Fernández M, Guxens M; INMA project. Prenatal exposure to hexachlorobenzene (HCB) and reproductive effects in a multicentre birth cohort in Spain.Sci Total Environ. 2014 Jan 1;466-467:770-6.