There has been a decrease in lead in the bodies of Quebecers since 2007, according to an update of an analysis by the INSPQ, but the impregnation of this toxic metal remains higher in Quebec compared to the rest of Canada.
This is what the Institut national de santé publique du Québec (INSPQ) shows in its update of the portrait of the Quebec population’s exposure to environmental chemicals. This report, published Thursday, is based on the results of the Canadian Health Measures Survey, which collected and analyzed blood and urine samples from thousands of participants.
“The objective of the report was to include as many substances as possible and at the end to have reference levels. So now we have hundreds of biomarkers available, before we had around 50 substances. Since we had several time points, we were able to see if there were changes in the impregnation with the previous data,” said the co-author of the portrait, Gabriela Ponce.
The INSPQ research team found that for all substances that had more than one time point, the impregnation was comparable or had decreased.
This is the case for lead, which went from an average in the first cycle (2007 to 2011) of 1.5 micrograms of lead per deciliter of blood to 0.96 micrograms per deciliter for the period 2016-2019.
Cadmium, a heavy metal that can have adverse health effects, also declined over the period analyzed. It went from a concentration of 0.36 micrograms per liter of blood for 2007-2011 to 0.24 micrograms per liter for 2016-2019.
Lead data is higher for Quebecers compared to the rest of Canada, and this is the case in all three periods analyzed. “But we see a decrease over time. We can say that we are on the right track,” commented M.me Ponce, adding that we are also seeing a reduction in the gaps between Quebec and Canada.
The INSPQ portrait highlights that the entire population is chronically exposed to a multitude of chemical contaminants through air, water, soil, food and consumer products.
Biomonitoring measures the concentration of these chemicals present in the environment in the body.me Ponce explained that the report was intended to facilitate the use of biomonitoring studies to better compare with future results. “It may allow for prioritization, to see if there are substances that deserve additional efforts,” she said.
These efforts could include, for example, continuing surveillance and determining which sources can influence the concentration of chemical substances in the body. “The goal of this portrait is to provide some food for thought for public health and see if it would be relevant to implement interventions or continue surveillance programs,” the researcher said.
Smoking decline as a hypothesis
Mme Ponce clarified that the impregnation data does not translate into a health impact. Rather, it is a way of painting a picture and knowing what the average impregnation is in order to identify trends.
“But it reflects lower exposure and that is certainly good news. […] It is not possible to calculate or estimate what the impact is. [sur la santé]but we can say that the impregnation of the general population has decreased and given that these are toxic substances, we could say that the risks associated with these substances have also decreased,” the researcher said.
The portrait does not target specific causes to explain the decreases observed over time or the gaps between Quebec and the rest of Canada, but it does propose certain hypotheses.
The INSPQ suggests that the downward trend in smoking could partly explain the drop in the concentration of cadmium and lead in the body. It also highlights the regulatory efforts made over decades to reduce or eliminate the presence of lead in the environment. The ban on lead in gasoline, paint and pipes and the replacement of lead service lines in drinking water systems “have likely contributed to the observed decrease in the impregnation of the general population” with lead.
The use of firewood and the higher smoking rate in Quebec compared to elsewhere in Canada could contribute to the differences in impregnation identified.
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