Postmortem absorption of dichloromethane: a case study and animal experiments

Assessment of Methylene Chloride-Related Fatalities in the United States, 1980-2018

Importance

Methylene chloride is a halogenated organic solvent widely used in paint strippers, cleaners, adhesives, and sealants. Despite label warnings and occupational standards, methylene chloride-related fatalities continue to occur in the United States.

Objective

To identify and analyze methylene chloride-related fatalities in the US.

Design, Setting, and Participants

For this case series, we conducted systematic searches of sources, including PubMed and government databases, for unintentional fatalities in the US that were associated with exposure to methylene chloride or products containing methylene chloride between 1980 and 2018. We reviewed all available information, including inspection reports, autopsy reports, and medical records; data analyses were conducted from August 2018 to August 2020. Cases were categorized as those occurring in the home (consumer deaths) or at work (occupational deaths).

Exposures

Methylene chloride or products containing methylene chloride.

Main Outcomes and Measures

To determine characteristics of the methylene chloride-related fatalities, we recorded demographic information; the setting; circumstances, including information on safety measures used, if available; and products used. Where medical records were available, we recorded toxicology results and autopsy findings. We also obtained data about nonfatal methylene chloride cases from the American Association of Poison Control Centers.

Results

From 1980 to 2018, 85 methylene chloride-related fatalities were identified in the US, including 74 (87%) in occupational settings; of those who died, 75 (94%) were men, and for the 70 cases with available information, the median (interquartile range) age of the decedents was 31 (24-46) years. Paint strippers were the most common products involved in methylene chloride-related fatalities (n = 60). The proportion of occupational fatalities related to paint stripping increased from 22 (55%) before 2000 to 30 (88%) after 2000. Similarly, occupational fatalities associated with bathtub or paint stripping in bathrooms increased from 2 (5%) before 2000 to 21 (62%) after 2000. From 1985 to 2017, the American Association of Poison Control Centers documented 37 201 nonfatal methylene chloride cases, with a decrease in the annual number of cases starting in the late 1990s.

Conclusions and Relevance

Results of this case series demonstrated that despite regulations to address the toxic effects of methylene chloride use for consumers and workers, there are continuing fatalities in the US, particularly in occupational settings. Prevention of fatalities associated with methylene chloride exposure should emphasize the use of safer substitutes, rather than hazard warnings or reliance on personal protective equipment.

Solvent-based paint and varnish removers: a focused toxicologic review of existing and alternative constituents

Paint and varnish removers constitute a major potential source of organic solvent exposure to contractors and home improvement enthusiasts. Unfortunately, the leading paint remover formulations have traditionally contained, as major ingredients, chemicals classified as probable human carcinogens (eg, methylene chloride) or reproductive toxicants (eg, N-methylpyrrolidone). In addition, because of its unique toxicology (ie, hepatic conversion to carbon monoxide compounding generic solvent narcosis and arrythmogenesis), high volatility, and rigorous requirements for personal protective equipment, methylene chloride exposures from paint removers have been linked to numerous deaths involving both occupational and consumer usage. The aim of this review is to summarize the known toxicology of solvent-based paint remover constituents (including those found in substitute formulations) in order to provide health risk information to regulators, chemical formulators, and end-users of this class of products, and to highlight any data gaps that may exist.

Bilateral hearing loss after dichloromethane poisoning: a case report

Dichloromethane is a widely used organic solvent. Occupational exposure to dichloromethane is frequent and can result in both acute and chronic toxicity, affecting mostly the central nervous system, directly or through its metabolite, carbon monoxide. The effects of dichloromethane on the peripheral nervous system are debated. Here we report the case of a 37-year-old woman who was accidentally exposed to dichloromethane. In the days following the incident she experienced bilateral hypoacusis. Hearing loss regressed after 25 days treatment with hyperbaric oxygen. This is the first report of sudden hearing loss after acute exposure to dichloromethane, suggesting a possible toxic effect of this solvent on the auditory system.

Fatal workplace accident involving ethyl acetate: a distribution study

The tissue distribution of ethyl acetate and ethanol in a case of acute intoxication by ethyl acetate is presented. The victim was a 39-year-old man who was found dead lying on his abdomen in the interior of a tank containing ethyl acetate. Confirmation of ethyl acetate was obtained with static headspace gas chromatography with mass spectrometry. In blood, rapid biotransformation of ethyl acetate occurs by plasma esterases resulting in acetic acid and ethanol. Quantitation of ethyl acetate and ethanol in the postmortem samples was performed using static headspace gas chromatography with flame ionization detector. N-butanol was used as internal standard. Separation of the compounds was obtained on a Supelcowaxtrade mark-10 Fused Silica capillary column. The method was linear over the specific ranges investigated and showed a within-run accuracy of 99.8 and 101.0% and a precision of 0.5 and 2.0% for ethanol and ethyl acetate, respectively. The postmortem samples were analyzed in duplicate or triplicate. Coefficients of variation were < or =4.51% for ethyl acetate and < or =0.52% for ethanol. The low ratios of the ethyl acetate concentration to the ethanol concentration found in the postmortem tissue samples confirmed the rapid in vivo biotransformation of ethyl acetate. The highest concentration of ethyl acetate was found in the testis indicating that postmortem percutane absorption may have occurred. To our knowledge, this is the first reported tissue distribution study of ethyl acetate and ethanol in a case of acute intoxication by ethyl acetate.

Vitreous humour as a complementary sample to blood for the detection/confirmation of diazepam: ante-mortem and post-mortem studies in an animal model

The quantification of medical or toxic substances in vitreous humour (VH) could be very useful in forensic toxicology when blood sample determinations are impossible due to absence or deterioration. However, few studies have been made in this area and even fewer have tried to find a relationship between drug levels in both samples. To determine a correlation ratio between blood and VH diazepam (DZ) levels, we performed an experimental study using rabbits administered with a sub-toxic dose of DZ under known and controlled conditions. Blood and VH samples were collected 0.5, 1, 2, 3 and 6 hours after the drug administration in order to determine DZ and its main active metabolite, desmethyldiazepam (DMD). In addition, we have studied an animal group sacrificed 2 hours after intramuscular (i.m.) drug administration with blood and VH collection 24 hours later, to evaluate the existence of possible post-mortem changes. After DZ administration, a fast absorption phase was observed with a plasma Cmax value 1 hour after, followed by a rapid concentration decrease, with a half-life of 1 hour, indicating that, besides elimination, a fast distribution to other organs and tissues and/or hepatic metabolism occurred. Diazepam Cmax value in VH was achieved between 1 and 2 hours, when plasma concentrations had already decreased to half the value. The plasma/VH DZ ratio calculated at this time was 10. In the post-mortem study, while plasma DZ concentration at 24 hours was smaller, DMD levels were higher than those at the time of death. In the VH, both DZ and DMD concentrations at 24 hours were higher than those obtained at the time of death. That is, in both fluids DZ and DMD concentrations were different from those at the time of death and post-mortem distribution and redistribution phenomena occurred. The combination of ante-mortem and post-mortem studies has allowed the determination of a correlation ratio for DZ in the rabbit of 6 x, comparing the concentrations in VH collected 24 hours after death with the concentrations detected in plasma at the time of death. This study opens new perspectives for the use of VH as a complementary sample to blood for DZ detection and confirmation. The putative relevance of the correlation ratio obtained, for forensic toxicology practice with medical substances, namely benzodiazepines, recommends further studies in humans.

The levels of kerosene components in biological samples after repeated dermal exposure to kerosene in rats

The current study was experimentally investigated using rats whether or not kerosene components are accumulated from daily repeated dermal exposure. Rats received daily 1h-exposure to kerosene for 5 days (5K), daily 1h-exposure for 4 days and left for 1 day (4KL), a single 1h-exposure (1K), a single 1h-exposure and left for 1 day (1KL), or a single 1h-exposure, sacrificed and left dead for 1 day (1KLD). Kerosene components, trimethylbenzenes (TMBs) and aliphatic hydrocarbons (AHCs) in blood and tissues were determined by GC-MS. In blood, almost the same concentrations of TMBs were detected in the rats sacrificed immediately after exposure (5K, 1K and 1KLD), and only trace levels were detected in the rats sacrificed 1 day after exposure (4 and 1KL). Almost the same levels of AHCs in blood were detected among groups except for the rats sacrificed 1 day after a single exposure (1KL), in which AHCs were slightly lower. These results suggest that (1) AHCs tend to be accumulated from daily exposure, while TMBs do not, (2) the proportions of detected kerosene components in blood can be an indicator of whether the last exposure occurred just before death or not, (3) the kerosene levels last at least 1 day without blood circulation.