Hydrocarbons

13/01/2015

Hydrocarbon song by 9th grade students

Project in Chemistry. A song about hydrocarbon. 9 Prudence

13/01/2015

Makinig at matuto. :)

JM Salamat's latest single this 2014. Hydrocarbon (Hydrogen Carbon). Eligraphics Productions.

13/01/2015

Phenol

Phenol (also known as Carbolic Acid) is a very common antiseptic agent. It has the unique property of numbing tissue, and in higher concentrations is a skin irritant resulting in painless defatting dermatitis that may progress relatively unnoticed by the hapless victim until they see a growing wound at the point of contact. Phenol is an active ingredient in sore throat sprays and lip balm, but is also an effective embalming fluid and euthanasia agent. Rescuers should proceed with caution around industrial phenol. If skin exposure occurs, it is best removed from the skin with isopropyl alcohol.

13/01/2015

Asphyxiation

All gaseous hydrocarbons and halogenated hydrocarbons can serve as simple asphyxiants, displacing oxygen from the environment. Carbon tetrachloride was a common fire extinguishent in the early 1900s. It worked by creating a dense cloud of oxygen-poor gas at the base of a fire. More recently, halon fire extinguisher systems were used to smother fires with the unfortunate side effect of occasionally smothering people as well. A basement with a 150 gallon fuel oil spill may represent an oxygen-poor environment as well as a potential fire hazard, and people who huff paint or glue experience euphoria from hypoxia in addition to the CNS depressive effects of the hydrocarbons they are inhaling. Most hydrocarbons have considerable v***r pressures, meaning that they can saturate the atmosphere to the degree that they present a significant risk of inhalation. Inhaling an aerosol or fine mist can cause chemical pneumonitis.

13/01/2015

Hydrocarbon toxicity

The most obvious danger from most hydrocarbons is their flammability and potential to explode under some conditions. The danger of fire or explosion is so familiar that we sometimes fail to appreciate the other toxic ramifications of these substances once the potential for fire has been mitigated.

13/01/2015

Combustion Emissions

Combustion emissions are sources of both direct risks due to inhalation and indirect risks from consumption of affected food products. These sources, such as vehicles, fires, and incineration facilities, emit contaminants in both the v***r and particle phases that are associated with incomplete combustion. Benzene, formaldehyde, and diesel particulates are the major components of vehicle exhaust that drive the estimated inhalation risks in urban areas, while PAHs and dioxins/furans often drive risk estimates for stationary sources, such as combustion facilities. Exponent personnel have conducted risk assessments for such diverse combustion sources as mining operations, hazardous waste combustion facilities, and motor vehicles, including diesel truck traffic. In addition, our personnel have served on technical advisory committees for regulatory agencies involved with these issues, ranging from the South Coast Air Quality Management District (SCAQMD) MATES II study of air toxics for the Los Angeles basin to the EPA’s hazardous waste incinerator guidance and national air toxics study.

13/01/2015

Gasoline Additives

The health risks posed by gasoline additives have received much attention in recent years, particularly since California began phasing out the use of methyl tert butyl ether (MTBE) in gasoline supplies in 1999. MTBE and other substances are added to reformulated gasoline to aid combustion and reduce emissions to meet requirements of the Clean Air Act. Although MTBE was effective in reducing emissions from automobile engines, it was viewed as a problem when released from leaking underground tanks to groundwater, or from two-stroke engines to surface water used for drinking supply, primarily because it imparts an unpleasant taste and odor to the water at relatively low concentrations. MTBE also has been identified as a potential carcinogen by some regulatory agencies. Exponent conducted extensive evaluations of MTBE in drinking-water sources in California and elsewhere in the U.S., as well as assessments of the health risks posed to consumers by MTBE in drinking water . In addition, Exponent has evaluated the risks and benefits of MTBE and ethanol as gasoline additives.

13/01/2015

Polynuclear Aromatic Hydrocarbons (PAHs)

Polynuclear aromatic hydrocarbons (PAHs) are often important contaminants of concern because of their chemical and toxicological properties. Composed of multiple aromatic rings, PAHs tend to be immobile and highly persistent in the environment, with relatively high bioaccumulation rates and toxicity. While PAHs occur naturally in crude oil and smoke and ash from forest fires, they are most often found as products of incomplete combustion, especially from incinerators. PAHs are often found at facilities formerly involved in creosote, coking, and wood preservative production, and at former manufactured gas plants that use coal as a feedstock. Exponent has conducted numerous risk assessments at these types of sites. Because of their accumulation in the food chain, PAHs usually drive the indirect risks associated with exposures via ingestion of soil, produce, fish, and animal products affected by emissions from hazardous waste combustion facilities. In conducting numerous human and ecological risk assessments for these facilities, we have determined that the methods used by EPA often overpredict concentrations in various media, and in many cases, we were able to get the EPA to modify its approach accordingly, thus reducing the estimated risk levels for PAHs.

13/01/2015

Assessing the health risks associated with the use of petroleum solvents requires additional consideration beyond those of a site risk assessment. Benzene is not added to petroleum solvents but was historically found in solvents, at relatively low levels, occurring as a contaminant in the distillate fraction that composes the majority of the solvent. Little is known about the benzene concentrations in many of these solvents, except that levels were less than 0.1 weight percent (1000 ppm by weight), which is the OSHA reporting limit for material safety data sheets (MSDSs). Therefore, the initial challenge in assessing benzene exposures from solvents is characterizing the benzene content of the solvent, knowing that solvent composition has changed over time to meet the requirements of federal and state air quality regulations. Exponent has collected a substantial amount of data on benzene concentrations in various distillate fractions (e.g., mineral spirits, petroleum naphthas), including other aromatic hydrocarbons such as toluene, to assist clients in characterizing their historical products. Exponent has also conducted laboratory studies to assess the effects of petroleum solvent composition and benzene concentration on benzene volatilization from the liquid solvent, and simulation studies to directly measure airborne benzene concentrations associated with the use of specific solvents. Much of the focus on petroleum solvents has been on the reconstruction of potential exposures of workers using historical formulations of petroleum solvents. Exponent has conducted exposure reconstructions for workers who used a variety of petroleum solvents, including parts-washing solvents, printing solvents, and penetrating oils.

13/01/2015

The aromatic hydrocarbons are identified as chemicals of interest for health risk assessments at most petroleum-contaminated sites and for sites affected by petroleum solvent. Benzene is the only aromatic hydrocarbon classified by the U.S. Environmental Protection Agency and other health and environmental agencies as a “known human carcinogen,” and therefore, is the primary focus of many petroleum hydrocarbon risk assessments. Exponent has conducted hundreds of site risk assessments where benzene was a chemical of concern. The potential exposure to benzene at a petroleum-contaminated site depends on the concentrations of benzene in the soil, water, and air, and the frequency and duration of expected human contact with the contaminated media. If the petroleum release was gasoline from an underground tank, benzene will likely be found in soils and possibly also in shallow groundwater and air. The volatilization of benzene in subsurface soils and shallow groundwater and its migration into buildings (v***r intrusion), have recently become a risk assessment focus that has led to the reopening of Records of Decision (RODs) at a number of sites. Benzene and the other aromatic hydrocarbons are taken up through the skin, lung, and digestive system, so all three routes of exposure (dermal uptake, inhalation, and incidental ingestion) need to be considered in assessing health risks.

13/01/2015

Risks of Hydrocarbons

Exposure to hydrocarbons is common in modern society. Hydrocarbons are easily accessible in products such as gasoline, turpentine, furniture polish, household cleansers, propellants, kerosene, and other fuels. Although hydrocarbons include all compounds composed predominantly of carbon and hydrogen, the compounds of interest are derived from petroleum and wood. Most of the dangerous hydrocarbons are derived from petroleum distillates and include aliphatic (straight-chain) hydrocarbons and aromatic (benzene-containing) hydrocarbons. Other hydrocarbons such as pine oil and turpentine are derived from wood.

Types of exposure include unintentional ingestion, intentional recreational abuse, unintentional inhalation, and dermal exposure or oral ingestion in a su***de attempt. The highest rates of morbidity and mortality result from accidental ingestion by children younger than 5 years. Aspiration pneumonitis is the most common complication of hydrocarbon ingestion, followed by CNS and cardiovascular complications.