University of São Paulo: Cases of mercury poisoning can be monitored by the SUS
In March of this year, Bill 1011/23 , which institutes the National Policy for the Prevention of Exposure to Mercury, reached the Federal Senate . The policy, which will be borne by the federal, municipal and state powers, aims to monitor cases of mercury poisoning and provide education on the subject.
The impacts on human health from mercury ingestion mainly affect the central and peripheral nervous system, in addition to the possibility of gastrointestinal, skin and eye corrosion by inorganic mercury salts. By consuming fish meat contaminated with methylmercury there is a risk of transplacental exposure, impairing fetal development, with mainly neurological impacts.
One of the differentials of the PL in question is the creation of a Mercury Exposure Control System (Sicem), which will serve as a platform for recording confirmed cases of exposure to mercury for health and research purposes.
Reference values
The individual with any amount of mercury in the body, even if it does not cause harm, is considered exposed to the substance. The World Health Organization establishes maximum mercury limits accepted in human monitoring samples, which consider hair, blood and urine. The values change depending on which sample is analyzed. Currently, WHO considers 2.3 micrograms of total mercury per gram of hair, 9.2 micrograms of total mercury per liter of blood and 50 micrograms of total mercury per gram of creatinine in urine. These values help to guide specific public policies, according to the specificities of each case of contamination.
Some groups are more vulnerable to damage caused by mercury, depending on their characteristics. “Although some individuals are subject to similar environmental exposures, differences between them can produce different levels of biological response. For example, children have a lower body mass than adults, in addition to being developing, and a lower dose of a given chemical can have a significant and negative impact on health,” says Kelly Polido Kaneshiro Olympio , professor at the Department of Environmental Health at the Faculty of Public Health at USP.
Some of the characteristics observed in the discussion of chemical exposures are genetic predisposition, age, lifestyle, diet, biological sex and profession, and guide the definition of reference values. “The reference values are obtained from studies that determine the concentration of the substances of interest in biological samples in a defined group of the general population”, explains Kelly.
The professor also points to the mutability of values: “Reference values are determined by following the upper limit of baseline exposure of the general population at a given time. Thus, they are dynamic values”. The values can be updated depending on the intoxicated group being analyzed, as well as the origin of the substance – whether it is anthropic or natural -, and are influenced by public policies to protect the health of the population and the reduction of environmental pollutants.
“The reference value does not, therefore, represent a criterion of normality for a toxicological analysis, but should be used to identify individuals with an increased level in relation to the baseline exposure of environmental exposure to a given substance”, he adds.
The Bill is in the public consultation phase and can be voted on the website of the Federal Senate.