Health and environmental concerns

Ethylene glycol is moderately toxic. On ingestion, ethylene glycol is oxidized to glycolic acid which is, in turn, oxidized to oxalic acid which is toxic. It is critically important that additives do not significantly increase the toxicity or make the coolant hazardous to the environment. This to a great extent limits the selection of inhibitors. 

In the case of KF, although fluorides are present throughout the environment at low levels and are not harmful (in fact, small amoimts of sodium fluoride can help prevent tooth decay) high levels of fluoride or hydrogen fluoride gas are hazardous to health [34]. Concentrated hydrogen fluoride is very corrosive and would badly burn exposed plants, birds or land animals. 

In a coolant system, the health and environmental hazards of fluoride are relatively low. This is because of the following  

Therefore, if KF is added to coolants to prevent the corrosion of magnesium alloys, the health and environmental issues may not be a major concern. 

Betties, C.T. Forwood, D. StJohn, et al., AMC-SCl An elevated temperature magnesium alloy suitable for precision sand casting of powertrain components , in H. Kaplan (ed). Magnesium Technology, TMS, San Diego (2003) pp. 223-226. 

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Report 36 Developments in Additives to Meet Health and Environmental Concerns, M.J. Forrest, Rapra Technology Ltd. 

None arc inogenic mineral oil-based plasticizers and extender oils are being utilized more and more in elastomer and tire formulations and this interest is prompted by the health and environmental concerns as well as by the coming EU legislation. 

Bridges, B. (2002) Fragrance emerging health and environmental concerns. 

Peter, A.L.J., Viraraghavan, T. (2005). Thalliiun a review of public health and environmental concerns. Environ. Int. 31 493-501. 

The organic pesticides contain carbon. They also contain hydrogen and often oxygen, nitrogen, phosphorus, sulfur, or other elements. Most pesticides used today are organic compounds. A few organic pesticides are either derived or extracted directly from plants. Most, however, are synthetic compounds. It is these compounds that have been responsible for the expanded use of pesticides since World War II. They are often extremely effective and easy to use, have been relatively lowcost and some are quite specific in their activity. They have, however, been the principal focus of health and environmental concerns and are the pesticides most commonly associated with problems of pesticide use and misuse. 

Passivation Inhibitors. Examples of passivators (anodic inhibitors) include chromate, nitrite, molybdate, and orthophosphate. AH are oxidizers and promote passivation by increasing the electrical potential of the iron. Chromate and nitrite do not require oxygen, and thus, can he the most effective. Chromate is an excellent aqueous corrosion inhibitor, particularly from a cost perspective. However, owing to health and environmental concerns, use of chromate has decreased significandy and will probably he outlawed soon. Nitrite is also an effective inhibitor, but in open systems it tends to be oxidized to nitrate. 

With regard to ectoparasiticides, public health and environmental concerns have led to the withdrawal of the organochlorines and organophos-phates in many countries. Since Elliot (1973) reported the first photostable synthetic pyrethroid, these compounds have both replaced the naturaUy occurring pyrethrins (extracted from chrysanthemum flowers) and progressively become the mainstay of external parasite control programs. 

Growth of the chemical industry has been more moderate since 1970. But during this third period, a combination of factors has Increased almost exponentially the focus on risks associated with chemicals, health and the environment. These factors Include advances in health and environmental technology, an increasing corporate responsibility toward health and environmental concerns, media spotlighting of new information cmd incidents, and increasing government and public Involvement in risk decisions. 

II. Health and Environmental Concerns with Diesel Particulate... 

Unleaded fuels reduce knocking in car engines and do not have the health and environmental concerns posed by leaded fuels. 

In addition, acetylene is prepared by passing methane through an electric arc. When methane is made to react with chlorine (gas), various chloromethanes are produced chloromethaue (CH3CI), dichloromethane (CH2CI2), chloroform (CHCI3), and carbon tetrachloride (CCy. However, the use of these chemicals, however, is declining—acetylene may be replaced by less costly substitutes— and the chloromethanes are used less often because of health and environmental concerns. 

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