Biosafety

Mercury disposal in the environment

Currently, Brazilian legislation is regarding to the levels of metals released into the environment, but not to the laws on the handling of toxic metals such as Mercury. Besides the error in the use of mercury in terms of quantity, there is another contradiction of laws related to the regulation since the national legislation which governs the drinking water is the Ministry of Health and the one to rule over the aquatic environmental systems is the National Environmental Council (CONAMA).

Based on CONAMA N° 357, March 17th, 2005, the classification of waters is valid for the entire national territory. The classification is done in 9 classes, and the resolution separates fresh water (salinity < 0.05 %) in five types: Special Class and Class 1 to 4, in which the restrictions impurities decrease as the number of the class increases. Saline waters are classified as Class 5 and 6, and brackish waters are Class 7 and 8. The resolution also determines the maximum allowable levels for effluent discharge into the waters, except for special class of waters that cannot receive releases wastewater as it is intended for domestic supply and should be absent of coliforms. For Class 1, the maximum mercury content allowed is 0.2 mg/L for Class 2 is 2 mg/L, for Classes 5 to 7 is 0.1 mg/L, and for other classes there’s no maximum levels specified.

For other waterbody (class 1-8), which are neither the sub-surface nor special class, is tolerated dumps that meet the specifications of maximum (Hg = 0.01 mg/L) and has a maximum flow of 1.5 times of the activity average daily period of agent launcher, as soon as they do not exceed the limits set for their classes. Thus, legislation allows a higher concentration in the effluent than in the waterbody, believing that there is dilution of which was released. However, it is known that there are many sources of pollution that contains the same harmful substance that discharge their effluent into the same body of water, this fact can lead to concentration of substance and exceed limits of resolution.

In summary, Brazilian legislation only attempts to control the discharge of effluents, it does not act in maintaining the environmental quality of the receiving waterbody. Another mistake made by the legislation is that it rules on concentration and not on the load of harmful substance, this makes any dump mercury is disposed within the parameters in a greater amount than another source that turns your mercury with a margin slightly above established standards. Thus, whoever offers most eviction and degrades the bodies of water cannot be penalized, while those who dumps acceptable amounts will be.

Mercury disposal in the lab environment

Mercury is a silver metal that is liquid at normal temperature and odorless, when the temperature is increased becomes more dense toxic and corrosive. It is a product harmful when inhaled, ingested or in contact, causing irritation to skin, eyes and respiratory system. The mercury is present in various forms (metallic, organic, inorganic Hg) and can be found in three oxidation states (0, +1 , +2) generally readily interconvertible in nature.

Both humans and animals are exposed to all forms through the environment. The mercury vapor present in the atmosphere is eventually converted to water soluble form and returns to the earth's surface in rainwater. At this point, two important chemical changes may occur. The metal can be reduced again to mercury vapor and returns to the atmosphere or can be methylated by microorganisms in sediment from water, including fresh or sea water.

The handling of heavy metals cannot be made in ordinary laboratories, without any degree of certainty (See Table below about the requirements). In the absence of a suitable laboratory handling heavy materials at the university, the team had to redesign one of UFAM_Brazil laboratories (read more) to use mercury. This lab will remain for future research conducted at the university for now on.

Safety in the tests:

To avoid harmful we have used mercury in a water solution. In its ionic form Hg2+ in Mercury(II) Chloride form (HgCl2), though stock solution to test our biobricks. To do it, we will only have to dilute the mercury to the wanted concentration using sterilized water. The disposal have been done following the sanitary rules.

What the law says?

Why are we using the requirements applied to health labs? There’s no regulation for the use of mercury in research. In addition, the Brazilian law does not establish how should be the handling of toxic metals. It mentions only regarding to their levels released into the environment, and it is not very accurate. This brings us to a question, how to control the amount of mercury in the environment if there is no control in handling it. Due to lack of appropriate legislation in not only to dump mercury but also for use in research, the team UFAM_Brazil have been engaged in trying to improve this legislation. (read more).

Sanitary requirements for the handling of mercury in laboratories (Applied to health labs).