Chemical control measure

Risk control. See Chemicals, control measures Precautions... 

In the EU, the current chemical control measures, based on a network of legislation for hazard communication and safety assessment, are soon to be dramatically revised. To set the scene for this forthcoming fundamental change to chemical control in the EU, the key facets of the existing measures are described briefly i.e., notification of new chemical substances, the relatively-limited measures to evaluate existing substances and hazard communication. There have been problems with the current scheme, principally the disparity between the safety data on new and existing substances. 

On 13 February 2001 the European Commission adopted the much-discussed White Paper Strategy for a Future Chemicals Policy (a. 10). The current EU chemical control measures were considered to result in too great a disparity between new and existing substances, with the high cost of new substance notification stifling innovation. Furthermore, although existing substances account for >99% by volume of chemicals in commerce, they were considered to be relatively poorly assessed and controlled in comparison with new substances. 

Inert dusts have been used traditionally as stored grain protectants, and there is increasing interest in their use as alternatives to chemical control measures. A number of studies demonstrating the efficacy of inert dusts as grain protectants have been reported (Desmarchelier and Dines, 1987), as structural treatments in empty stores (Bridgeman, 1994) and as surface treatments in conjunction with aeration (Nickson et al., 1994). Diatomaceous earths (DEs) have been registered for storage use in USA, Canada, Australia, Japan, Indonesia and Saudi Arabia. 

There are many legal and administrative provisions controlling chemicals in the USA. Compliance with the various measures is often strictly monibned and enforced, and penalties for non-compliance can be severe. The chemical control measures of the Toxic Substances Control Act [13,30] are highlighted below. 

Between 1961 and 1975, about 400,000 kg of mirex were used in pesticidal formulations, of which approximately 250,000 kg were sold in the southeastern U.S. for control of native and imported fire ants (Solenopsis spp.) most of the rest was exported to Brazil for use in fire ant control in that country. Mirex was also used to control big-headed ant populations in Hawaiian pineapple fields, Australian termites. South American leaf cutter ants. South African harvester termites, and, in the U.S., western harvester ants and yellow jackets. Chemical control measures for imported fire ants began in the southeastern U.S. during the 1950s with the use of heptachlor, chlordane, and dieldrin. The large mounds built by ants in cultivated fields were believed to interfere with mowing and harvesting operations, the vicious sting of the insects presented a hazard to workers... 

Revisions are being made to chemical control measures by describing the key facts and objectives of future chemicals policy in EU legislation through the Registration, Evaluation and Authorisation of Chemicals (REACH) regulation, which will be effective in 2007. REACH is expected to have major implications for European chemical producers and downstream users, since it is anticipated that around 30,000 chemicals will need to be screened for their health and environmental impact [8, 33, 34, 35]. 

Even in the highly regulated European market there is a constant flow of new regulations. This inevitably means that any publication like this chapter will soon be outdated. Two white papers signal the plans for far-reaching changes to the chemical control measures in the European Union ... 

The most effective chemical control measures against hydrogen sulfide (sour) corrosion are removal of the hydrogen sulfide from the water by counter-current gas stripping or by cleaning the steel periodically with acid to allow access of the inhibitor to the metal surface. Steel sometimes can be cleaned sufficiently for inhibition to be effectively by the use of a powerful wetting agent. 

Chemical Reaction Measurements. Experimental studies of incineration kinetics have been described (37—39), where the waste species is generally introduced as a gas in a large excess of oxidant so that the oxidant concentration is constant, and the heat of reaction is negligible compared to the heat flux required to maintain the reacting mixture at temperature. The reaction is conducted in an externally heated reactor so that the temperature can be controlled to a known value and both oxidant concentration and temperature can be easily varied. The experimental reactor is generally a long tube of small diameter so that the residence time is well defined and axial dispersion may be neglected as a source of variation. Off-gas analysis is used to track both the disappearance of the feed material and the appearance and disappearance of any products of incomplete combustion. 

Table 6.11 Control measures for working with flammable chemicals...

The Material Safety Data Sheet (MSDS) is a detailed information bulletin prepared by the manufacturer or importer of a chemical tliat describes tlie physical and healtli hazards, routes of exposure, precautions for safe handling and use, emergency and first-aid procedures, and control measures. Infonnation on an MSDS aids in tlie selection of safe products and helps prepare employers and employees to respond effectively to daily exposure situations as well as to emergency situations. It is also a source of information for identifying chemical hazards. 

Chemically reactive elements should have a short residence time in seawater and a low concentration. A positive correlation exists between the mean ocean residence time and the mean oceanic concentration however, the scatter is too great for the plot to be used for predictive purposes. Whitfield and Turner (1979) and Whitfield (1979) have shown that a more important correlation exists between residence time and a measure of the partitioning of the elements between the ocean and crustal rocks. The rationale behind this approach is that the oceanic concentrations have been roughly constant, while the elements in crustal rocks have cycled through the oceans. This partitioning of the elements may reflect the long-term chemical controls. The relationship can be summarized by an equation of the form... 

Additional considerations, e.g. relating to labelling, information supply, emergency procedures, arise when marketing and transporting chemicals. While — as with Chapter 11 and with control measures generally — what is required will vary with specific legislation, basic requirements are summarized in Chapter 12. 

For most chemicals, inhalation is the main route of entry into the body. However, certain chemicals (e.g. phenol, aniline, certain pesticides) can penetrate intact skin and so become absorbed into the body. This may occur through local contamination, e.g. from a liquid splash, or through exposure to high vapour concentrations. Special precautions to avoid skin contact are required with these chemicals and potential exposure via skin absorption has to be taken into account when assessing the adequacy of control measures. Chemicals able to penetrate intact skin are listed in Table 4.2. 

---