Donald Lucas

Halogenated flame retardants: do the fire safety benefits justify the risks?

Since the 1970s, an increasing number of regulations have expanded the use of brominated and chlorinated flame retardants. Many of these chemicals are now recognized as global contaminants and are associated with adverse health effects in animals and humans, including endocrine and thyroid disruption, immunotoxicity, reproductive toxicity, cancer, and adverse effects on fetal and child development and neurologic function. Some flame retardants such as polybrominated diphenyl ethers (PBDEs) have been banned or voluntarily phased out by manufacturers because of their environmental persistence and toxicity, only to be replaced by other organohalogens of unknown toxicity. Despite restrictions on further production in some countries, consumer products previously treated with banned retardants are still in use and continue to release toxic chemicals into the environment, and the worldwide use of organohalogen retardants continues to increase. This paper examines major uses and known toxic effects of commonly-used organohalogen flame retardants, replacements for those that have been phased out, their combustion by-products, and their effectiveness at reducing fire hazard. Policy and other solutions to maintain fire safety while reducing toxicity are suggested. The major conclusions are: (1) Flammability regulations can cause greater adverse environmental and health impacts than fire safety benefits. (2) The current options for end-of-life disposal of products treated with organohalogens retardants are problematic. (3) Life-cycle analyses evaluating benefits and risks should consider the health and environmental effects of the chemicals, as well as their fire safety impacts. (4) Most fire deaths and most fire injuries result from inhaling carbon monoxide, irritant gases, and soot. The incorporation of organohalogens can increase the yield of these toxic by-products during combustion. (5) Fire-safe cigarettes, fire-safe candles, child-resistant lighters, sprinklers, and smoke detectors can prevent fires without the potential adverse effects of flame retardant chemicals. (6) Alternatives to organohalogen flame retardant chemicals include using less flammable materials, design changes, and safer chemicals. To date, before evaluating their health and environmental impacts, many flame retardant chemicals have been produced and used, resulting in high levels of human exposure. As a growing literature continues to find adverse impacts from such chemicals, a more systematic approach to their regulation is needed. Before implementing new flammability standards, decision-makers should evaluate the potential fire safety benefit versus the health and environmental impacts of the chemicals, materials, or technologies likely to be used to meet the standard. Reducing the use of toxic or untested flame retardant chemicals in consumer products can protect human and animal health and the global environment without compromising fire safety.

Particle-induced artifacts in the MTT and LDH viability assays

In vitro testing is a common first step in assessing combustion-generated and engineered nanoparticle-related health hazards. Commercially available viability assays are frequently used to compare the toxicity of different particle types and to generate dose-response data. Nanoparticles, well-known for having large surface areas and chemically active surfaces, may interfere with viability assays, producing a false assessment of toxicity and making it difficult to compare toxicity data. The objective of this study is to measure the extent of particle interference in two common viability assays, the MTT reduction and the lactate dehydrogenase (LDH) release assays. Diesel particles, activated carbon, flame soot, oxidized flame soot, and titanium dioxide particles are assessed for interactions with the MTT and LDH assay under cell-free conditions. Diesel particles, at concentrations as low as 0.05 μg/mL, reduce MTT. Other particle types reduce MTT only at a concentration of 50 μg/mL and higher. The activated carbon, soot, and oxidized soot particles bind LDH to varying extents, reducing the concentration measured in the LDH assay. The interfering effects of the particles explain in part the different toxicities measured in human bronchial epithelial cells (16HBE14o). We conclude that valid particle toxicity assessments can only be assured after first performing controls to verify that the particles under investigation do not interfere with a specific assay at the expected concentrations.

San Antonio Statement on Brominated and Chlorinated Flame Retardants

We, scientists from a variety of disciplines, declare the following: Parties to the Stockholm Convention have taken action on three brominated flame retardants that have been listed in the treaty for global elimination. These substances include components of commercial penta-bromodiphenyl ether and commercial octa-bromodiphenyl ether, along with hexabromobiphenyl. Another brominated flame retardant, hexabromocyclododecane, is under evaluation. Many commonly used brominated and chlorinated flame retardants can undergo long-range environmental transport. Many brominated and chlorinated flame retardants appear to be persistent and bioaccumulative, resulting in food chain contamination, including human milk. Many brominated and chlorinated flame retardants lack adequate toxicity information, but the available data raises concerns. Many different types of brominated and chlorinated flame retardants have been incorporated into products even though comprehensive toxicological information is lacking. Brominated and chlorinated flame retardants present in a variety of products are released to the indoor and outdoor environments. Near-end-of-life and end-of-life electrical and electronic products are a growing concern as a result of dumping in developing countries, which results in the illegal transboundary movement of their hazardous constituents. These include brominated and chlorinated flame retardants. There is a lack of capacity to handle electronic waste in an environ-mentally sound manner in almost all developing countries and countries with economies in transition, leading to the release of hazardous substances that cause harm to human health and the environment. These substances include brominated and chlorinated flame retardants. Brominated and chlorinated flame retardants can increase fire toxicity, but their overall benefit in improving fire safety has not been proven. When brominated and chlorinated flame retardants burn, highly toxic dioxins and furans are formed. Therefore, these data support the following: Brominated and chlorinated flame retardants as classes of substances are a concern for persistence, bioaccumulation, long-range transport, and toxicity. There is a need to improve the availability of and access to information on brominated and chlorinated flame retardants and other chemicals in products in the supply chain and throughout each product’s life cycle. Consumers can play a role in the adoption of alternatives to harmful flame retardants if they are made aware of the presence of the substances, for example, through product labeling. The process of identifying alternatives to flame retardants should include not only alternative chemicals but also innovative changes in the design of products, industrial processes, and other practices that do not require the use of any flame retardant. Efforts should be made to ensure that current and alternative chemical flame retardants do not have hazardous properties, such as mutagenicity and carcinogenicity, or adverse effects on the reproductive, developmental, endocrine, immune, or nervous systems. When seeking exemptions for certain applications of flame retardants, the party requesting the exemption should supply some information indicating why the exemption is technically or scien-tifically necessary and why potential alternatives are not technically or scientifically viable; a description of potential alternative processes, products, materials, or systems that eliminate the need for the chemical; and a list of sources researched. Wastes containing flame retardants with persistent organic pollutant (POP) characteristics, including products and articles, should be disposed of in such a way that the POP content is destroyed or irreversibly transformed so that they do not exhibit the charac-teristics of POPs. Flame retardants with POP characteristics should not be permitted to be subjected to disposal operations that may lead to recovery, recycling, reclamation, direct reuse, or alternative uses of the substances. Wastes containing flame retardants with POP properties should not be transported across international boundaries unless it is for disposal in such a way that the POP content is destroyed or irreversibly transformed. It is important to consider product stewardship and extended producer responsibility aspects in the life-cycle management of products containing flame retardants with POP properties, including electronic and electrical products.

Cellular response to diesel exhaust particles strongly depends on the exposure method

In vitro exposure to aerosols at the air-liquid interface (ALI) preserves the physical and chemical characteristics of aerosol particles. Although frequently described as being a more physiologic exposure method, ALI exposure has not been directly compared with conventional in vitro exposures where the particles are suspended in medium. We exposed immortalized human bronchial epithelial cells (16HBE14o) to aerosolized diesel exhaust particles at the ALI and to suspensions of collected particles. The response of the cells was determined from measurements of the cell viability and interleukin-8 (IL-8) secretion. The deposited size distribution at the cell surface was measured with transmission electron microscopy to obtain a dose for the ALI exposure. Although exposure by either method caused a slight decrease in cell viability and induced IL-8 secretion, the response to ALI exposure occurred at doses several orders of magnitude lower than exposure to particles in suspension. The most likely sources for the different dose responses are the artifacts introduced during the collection and resuspension of particles for conventional suspension exposures. The number concentration of particles deposited at the ALI is similar to the modeled deposition in the tracheal-bronchial region in a human lung, but the ALI size distribution is skewed toward particles larger than those deposited in the lung.

Gold nanoparticle films as sensitive and reusable elemental mercury sensors

We demonstrate the utility of gold nanoparticles (AuNPs) as the basis of a stand-alone, inexpensive, and sensitive mercury monitor. Gold nanoparticles absorb visible light due to localized surface plasmon resonance (LSPR), and the absorbance changes when mercury combines with the gold nanoparticles. The sensitivity of the peak absorbance is proportional to the surface-area-to-volume ratio. We chose 5 nm spheres because they have the largest surface-area-to-volume ratio while still having a peak absorption in the visible range. The adsorption of 15 atoms of Hg causes a 1 nm shift in the LSPR wavelength of these particles. Assembled into a film using the Langmuir-Blodgett method, the AuNP LSPR can be tracked with a simple UV-vis spectrometer. The rate of shift in the peak absorbance is linear with mercury concentrations from 1 to 825 μg(Hg)/m(air)(3). Increasing the flow velocity (and mass transfer rate) increases the peak shift rate making this system a viable method for direct ambient mercury vapor measurements. Regeneration of the sensing films, done by heating to 160 °C, allows for repeatable measurements on the same film.

Ignition by excimer laser photolysis of ozone

Abstract We have ignited mixtures of hydrogen, oxygen, and ozone in closed cells with 248 nm radiation from a KrF excimer laser. Ozone, the only significant absorber in this system, absorbs a single photon and produces oxygen atoms which initiate combustion. A discretized, time-dependent Beers law model is used to demonstrate that the radical concentration immediately after photolysis is a function of laser power, ozone concentration, focal length, and separation between the lens and reaction cell. Spark schlieren photographs are used to visualize the ignition events and identify the ignition sites. The effects of equivalence ratio, pressure, and the initial gas temperature on the minimum ozone concentration needed to produce ignition are presented, and only the initial temperature has a significant effect. Modeling studies of the ignition process aid in the interpretation of the experimental results, and show that the ignition we observe is not due solely to thermal effects, but is strongly dependent on the number and type of radicals present initially after photolysis. Ignition using other hydrocarbons as fuels was also demonstrated.

Bent Silica Fiber Evanescent Absorption Sensors for Near-Infrared Spectroscopy:

Silica optical fibers have been modified to improve their sensitivity as evanescent wave sensors for liquids. A section of fiber is stripped of its cladding and bent or coiled, which significantly increases the evanescent wave interaction with the surrounding environment. The effect of sensor shape, solute concentration, refractive index, and temperature on the sensor response is discussed.

Inverted co-flow diffusion flame for producing soot

We developed an inverted, co-flow, methane/air/nitrogen burner that generates a wide range of soot particles sizes and concentrations. By adjusting the flow rates of air, methane, and nitrogen in the fuel, the mean electric mobility diameter and number concentration are varied. Additional dilution downstream of the flame allows us to generate particle concentrations spanning those produced by spark-ignited and diesel engines: particles with mean diameters between 50 and 250 nm and number concentrations from 4.7 {center_dot} 10{sup 4} to 10{sup 7} cm{sup -3}. The range of achievable number concentrations, and therefore volume concentrations, can be increased by a factor of 30 by reducing the dilution ratio. These operating conditions make this burner valuable for developing and calibrating diagnostics as well as for other studies involving soot particles.

Characterization of the selective reduction of NO by NH3

LBL-12215 Submitted for presentation at the Western States Section of the Combustion Institute, Pullman, WA, April 13-14, 1981 CHARACTERIZATION OF THE SELECTIVE REDUCTION OF NO BY NH D. Lucas and N.J. Brown April 1981 TWO-WEEK LOAN COPY This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy, call Tech. Info. Diu is ion, Ext. 6782 Prepared for the U.S. Department of Energy under Contract W-7405-ENG-48

Metal Emissions Monitoring Using Excimer Laser Fragmentation-Fluorescence Spectroscopy

Abstract Photofragmentation of molecules using an excimer laser with subsequent detection of fluorescence from metal atoms formed in excited states is a viable detection strategy for many metal species. Excimer laser fragmentation-fluorescence spectroscopy (ELFFS) can provide continuous, real-lime monitoring information for metals which evolve from a variety of high-temperature processes, including combustion, Here we apply ELFFS to lead, manganese, nickel and chromium species in the postflame gases of a laboratory burner. Using a 193-nm argon fluoride laser we obtain quantitative relationships between signal strength and concentration in hot combustion products for metals injected into a flame; representative spectra are shown. The effects of quenching environment and laser power on the signal are discussed. The ELFFS technique is sensitive, providing ppb detection limits for these metals in a one-second measurement time.