Deaths associated with inhalant abuse in Virginia from 1987 to 1996

Analytical method for evaluation of exposure to benzene, toluene, xylene in blood by gas chromatography preceded by solid phase microextraction

Frequency of intentional exposure to organic solvents has been increasing among children and adolescents in Brazil. Analysis of benzene, toluene and xylenes (BTX) in human blood is necessary to diagnose the intentional and accidental exposure to these solvents. A method for BTX determination in blood samples by gas chromatography preceded by solid phase microextration (SPME) from headspace (HS) has been described. SPME has several advantages when compared to other extraction techniques such as simplicity, low cost and solvent-free extraction. The method presents good repeatability (precision was of 2.2-8.0%), accuracy from -4.7 to -9.4%, limit of detection <1.0 ug/mL, linearity from 1.0 to 100 ug/mL for toluene and from 5.0 to 100 ug/mL for the other solvents (R2 > 0.99), which shows to be efficient and adequate for the detection of exposure to BTX in blood samples.

Measuring Inhalant Abuse Among Homeless Youth in Southern Brazil

In order to measure urinary level of hippuric acid among Brazilian homeless youth suspected of having inhaled toluene in previous hours, urine samples were voluntarily collected from the youth around two hours after they arrived at an "open-school" in Porto Alegre, Brazil. Hippuric acid levels were determined by gas chromatography in urine specimens of 50 homeless children and adolescents. In 86% of the urine specimens, hippuric acid levels were within the range of 3.6 g/g creatinine and 46.1 g/g creatinine. Very high urinary hippuric acid level may indicate voluntary toluene abuse. A cut-off urinary hippuric acid level value needs to be established for toluene self-exposure diagnosis.

Stability of toluene and reduction of acetone to 2-propanol in homogenates of the human liver, brain and lungs

The homogenates of the livers, lungs and brains collected from five different cadavers were placed in the desiccator filled with vapours of rubber glue solvents and the concentrations of toluene, acetone and 2-propanol were determined during the 28-day storage at +25, +4 and -20 degrees C. It was demonstrated that only freezing of the material stabilised the initial concentration of these three xenobiotics while cooling to +4 degrees C resulted in limited conversion of acetone to 2-propanol and additionally reduced the biodegradation of toluene in the brain homogenates. Moreover, it was showed that at +25 degrees C the loss of acetone was almost equimolarly balanced by the 2-propanol increase, which allowed to estimate the initial concentration of acetone with the mean error of about 10%.

Inhibition of cardiac sodium currents by toluene exposure

Toluene is an industrial solvent widely used as a drug of abuse, which can produce sudden sniffing death due to cardiac arrhythmias. In this paper, we tested the hypothesis that toluene inhibits cardiac sodium channels in Xenopus laevis oocytes transfected with Nav1.5 cDNA and in isolated rat ventricular myocytes. In oocytes, toluene inhibited sodium currents (INa+) in a concentration-dependent manner, with an IC50 of 274 microm (confidence limits: 141-407 microm). The inhibition was complete, voltage-independent, and slowly reversible. Toluene had no effect on: (i). the shape of the I-V curves; (ii). the reversal potential of Na+; and (iii). the steady-state inactivation. The slow recovery time constant from inactivation of INa+ decreased with toluene exposure, while the fast recovery time constant remained unchanged. Block of INa+ by toluene was use- and frequency-dependent. In rat cardiac myocytes, 300 microm toluene inhibited the sodium current (INa+) by 62%; this inhibition was voltage independent. These results suggest that toluene binds to cardiac Na+ channels in the open state and unbinds either when channels move between inactivated states or from an inactivated to a closed state. The use- and frequency-dependent block of INa+ by toluene might be responsible, at least in part, for its arrhythmogenic effect.

Unusual facial markings and lethal mechanisms in a series of gasoline inhalation deaths

A review of deaths associated with hydrocarbon toxicity from gasoline sniffing in South Australia throughout a 10 year period from July 1987 to June 2002 revealed 4 cases. The victims were all Aboriginal people from remote inland communities. Each death had occurred while the victim was lying in bed sniffing gasoline from a can held to the face. Once unconsciousness had occurred, the mouth and nose had been pressed firmly against the can by the weight of the head. In each case, the effects of gasoline toxicity had been exacerbated by hypoxia and hypercapnia from rebreathing into the container once a tight seal had been established between the face and the can. The circular impressions left by the can edges on the faces of each of the victims provided an autopsy marker that assisted in clarifying the details of the fatal episodes. Discouraging solitary gasoline sniffing in bed may reduce the death rate in communities where this behavior is practiced.

Cardiac sensitization: methodology and interpretation in risk assessment

An increased sensitivity of the heart to endogenous epinephrine (adrenaline), a phenomenon referred to as cardiac sensitization, has long been recognized as a risk during exposure to hydrocarbons, principally halogenated hydrocarbons. Cardiac sensitization, which can result in serious arrhythmia and death, requires a certain critical blood level of both the sensitizing agent and epinephrine. The original research and methods utilized an exogenous epinephrine challenge during inhalation exposure to a chemical to assess cardiac sensitization potential in Beagle dogs. These screening tests were developed about 30 years ago, although in the last 15 years some modifications of these methods have occurred in response to testing chlorofluorocarbon (CFC) replacements. Results from these experimental cardiac sensitization studies have been used for semi-quantitative risk evaluation for occupational exposures but now are being used more quantitatively for regulatory purposes. The risks associated with cardiac sensitization from CFC replacements are unknown but expected to be low based on cardiac sensitization studies in the 1970s where dogs were made to generate their own adrenaline. With the advent of physiologically based pharmacokinetic (PBPK) modeling, greater emphasis is being placed on quantitative risk assessment for cardiac sensitization. In this investigation, we have examined the various methodologies used for detection of cardiac sensitization and discussed their limitations and advantages. In addition, we examined the potential concerns involved in using experimental cardiac sensitization data and PBPK modeling to predict exposure scenarios.

Inhalant abuse in the pediatric population: a persistent challenge

Inhalants remain one of the most commonly abused substances by adolescents in the United States today. Recent epidemiologic studies have demonstrated a decrease in the prevalence of inhalant abuse, but overall rates remain high. Inhalants have the potential to result in serious organ system dysfunction or even sudden death. This article reviews the most recent epidemiologic data on inhalant abuse, summarizes the types of substances used and their mechanism of actions, and discusses clinical toxicity and medical management.

Deaths related to the inhalation of volatile substances in Texas: 1988-1998

Analysis of death certificates in Texas from 1988 to 1998 showed that the characteristics of 144 Texans for whom inhalants were mentioned as a contributing cause of death are different from those Texans who report use of inhalants in surveys and from persons who died from inhalant abuse in Virginia. While Texas surveys show little difference in prevalence of use between white and Hispanic adolescents or between boys and girls, Texas death data indicate inhalant use is also a problem among adult white males. The mean age of decedents was 25.6 years (SD 9.8 years), and ages ranged from 8 to 62 years. There were 92% males, 81% whites, and 17% Hispanics. Of the death certificates, 35% mentioned Freon, and 25% mentioned chlorinated hydrocarbons. Of those with the mention of Freon, 42% were students (mean age 16.4 years), and 37% were mechanics, installers, and repairers (mean age 27.4 years), occupations in which Freon can be readily available. Of the chlorinated hydrocarbon deaths, 49% were students (mean age 17.5 years), and 51% were from other occupations (mean age 27.4 years). Research on drug use and the workplace is not extensive, and the effects of inhalant intoxication can be a serious problem in the workplace. Prevention campaigns need to inform the public that inhalant abuse is not just a problem among youngsters, and intervention services for adult abusers should be provided within the context of employee assistance programs.

Effects of volatile solvents on recombinant N-methyl-D-aspartate receptors expressed in Xenopus oocytes

1. We have previously shown that toluene dose-dependently inhibits recombinant N-methyl-D-aspartate (NMDA) receptors at micromolar concentrations. This inhibition was rapid, almost complete and reversible. The NR1/2B combination was the most sensitive receptor subtype tested with an IC(50) value for toluene of 0.17 mM. 2. We now report on the effects of other commonly abused solvents (benzene, m-xylene, ethylbenzene, propylbenzene, 1,1,1-trichlorethane (TCE) and those of a convulsive solvent, 2,2,2-trifluoroethyl ether (flurothyl), on NMDA-induced currents measured in XENOPUS oocytes expressing NR1/2A or NR1/2B receptor subtypes. 3. All of the alkylbenzenes and TCE produced a reversible inhibition of NMDA-induced currents that was dose- and subunit-dependent. The NR1/2B receptor subtype was several times more sensitive to these compounds than the NR1/2A subtype. 4. The convulsant solvent flurothyl had no effect on NMDA responses in oocytes but potently inhibited ion flux through recombinant GABA receptors expressed in oocytes. 5. Overall, these results suggest that abused solvents display pharmacological selectivity and that NR1/2B NMDA receptors may be an important target for the actions of these compounds on the brain.

Diagnosis and treatment of teen drug use

Small but significant decreases in adolescent abuse of tobacco, alcohol, and marijuana in recent national surveys allow clinicians to feel some optimism about defeating the specter of substance abuse. It appears that changing the perception of risk and increasing adolescent disapproval of substance abuse are key goals. For every adolescent, reducing risk factors while identifying and enhancing protective factors optimizes an individual's opportunity to avoid potentially harmful behaviors. While focusing energy and commitment on each adolescent, however, clinicians cannot ignore the need for wider social change because the proximal adolescent domains of individual, family, and school factors are interrelated and embedded in the community and societal contexts. Every sector in society plays a crucial role in preventing adolescents from experimenting with and continuing to abuse tobacco, alcohol, or illicit drugs, from parents, physicians, educators, and policy makers to every adult invested in the health and well-being of adolescents.