Brominated flame retardants (BFRs) are a diverse group of chemicals, which are used to slow down or inhibit the development of fires. BFRs are incorporated into a wide range of consumer products that are considered as potential fire hazards, such as TV-sets, household appliances, computers, and textiles. The production and use of BFRs is extensive and consists of mainly tetrabromobisphenol A (TBBPA), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecan (HBCD). BFRs in general, but in particular the PBDEs, have led to both scientific and public concern since they have been found to bioaccumulate in humans and wildlife. The general population is targeted by the PBDEs due to their applications and via the food web. Occupational exposure occurs not only during direct handling of BFRs, but also during handling, repair and dismantling of flame retarded goods. This thesis is aimed to assess occupational exposure to BFRs. It is mainly focused PBDEs and especially the PBDEs with high bromine content, such as decabromodiphenyl ether (BDE-209). The work has been accomplished by analysis of BFRs in indoor air at industries handling BFRs or flame retarded goods, and by analysis of blood drawn from workers with potential exposure to BFRs. A referent group, abattoir workers with no occupational exposure to PBDEs, was also investigated. Data from these cross-sectional investigations and from serum sampling during vacation in PBDE-exposed workers have been used for calculation of apparent halflives of hepta- to decaBDE in serum. The results clearly show that the workers were exposed to PBDEs when handling PBDE containing products or goods. The serum PBDE levels in computer technicians were found to correlate to the estimated cumulative work hours with computers. Exceptionally high concentrations of BDE-209, almost up to 300 pmol/g lipid weight (l.w.) were observed in serum from rubber workers manufacturing or handling rubber compound that was flame retarded with a technical mixture of decabromodiphenyl ether (DecaBDE). Elevated concentrations of PBDEs with eight or nine bromine substituents were also observed. In an electronics dismantling plant, where elevated levels of PBDEs previously had been observed, reduced serum levels of some, but not all PBDE congeners were observed after industrial hygiene improvements. Notably, it was observed that the BDE-209 concentrations in referents with no occupational exposure were similar to the concentrations of 2,2’,4,4’- tetrabromodiphenyl ether (BDE-47), often referred to as the most abundant PBDE congener in humans and wildlife. Additionally, PBDEs with high bromine content were found to have a fast rate of elimination or transformation in humans, based on serum analysis. BDE-209 had an apparent half-life in serum of only 15 days. The possibility of quantifying BFRs, such as PBDEs, in human serum at low levels of detection has been achieved by reducing the contamination of the samples and procedural blanks. Major efforts have been done to develop routines and clean up methodology to enable an almost contamination-free environment at the laboratory. The use of a clean room has decreased PBDE levels in the blanks to acceptable limits. The modifications of the original analytical method have made it possible to quantify almost all PBDE congeners of interest in one GC/MS run. Occupational and general background exposure of BFRs to humans will continue as long as these chemicals are a part of our daily life and present as environmental contaminants. The present scientific knowledge of the potential health risks of these BFRs still needs to be further developed. It should be stressed that health effects to PBDEs have not been assessed in this work. It is the author's wish that this thesis should add another piece of knowledge to the puzzle of BFRs and BFR exposure to humans and that these data will be used in future risk assessments of PBDEs in particular.

Poly Brominated Diphenyl Ethers (PBDEs) are known flame retardants with highly persistent and lipophilic in nature. The continued usage of PBDE in various products amplifies the human burden of PBDEs. It is therefore, important to study the potential toxicological and/or biological effects of PBDE exposure in human. In this study we investigated the mode of action of PBDE induced toxicity in human liver by exposing human hepatocarcinoma cells in a time (24-72h) and dose (0-100μM) dependent manner. The highest test dose caused an inhibition in cell viability up to 50% after 72h, whereas lower doses (<50μM) showed slight increase in cell viability. Likewise, higher doses caused significant accumulation of intracellular ROS over time. Further, increase in caspase-3 enzyme levels and DNA fragmentation showed that, lower brominated PBDEs induce liver toxicity through accumulation of toxic metabolites and reactive oxygen species over time leading to caspase-mediated apoptotic cell death.

Cada any milers d'hectàrees forestals es destrueixen a causa dels incendis forestals. Investigar quins són els mecanismes que controlen la ignició i la propagació dels incendis forestals és necessari per planificar estratègies eficients de lluita contra els incendis forestals i per establir plans de gestió de les àrees forestals. Durant aquests darrers seixanta anys des del món de la recerca s'han formulat models per descriure el comportament dels focs forestals de superfície, principalment, i en un menor grau els focs de capçades. No obstant, aquests models tenen un punt feble significatiu: cap d'ells ha estat desenvolupat per ser utilitzat com a eina predictiva del comportament del foc després d'actuacions d'atac indirecte amb retardants a llarg termini (o retardants). A més, la majoria de treballs desenvolupats fins ara amb retardants a llarg termini han tingut l'objectiu d'avaluar diferents productes per al seu ús públic per comparació amb un de referència.L'objectiu del present estudi ha estat millorar el coneixement sobre l'efecte dels retardants a llarg termini en el comportament dels incendis forestals. L'efecte dels retardants sobre la intensitat del front de flames ha estat quantificat per a diferents condicions (sense pendent/sense vent, sota la influència del vent, sota la influència del pendent), així com l'efecte dels retardants sobre la calor de combustió del combustible forestal i l'emissivitat de la flama. Avaluar com varien aquests dos últims paràmetres per la presència de retardant al combustible és un primer pas per incloure en els models de propagació l'efecte de les operacions d'atac indirecte amb retardants.Per a les condicions experimentals provades en aquest estudi, hem trobat que la intensitat del front de flames es redueix en un factor de 0.8 per la presència de retardant. També s'ha observat que la quantitat de calor alliberada durant la combustió amb flama es redueix en un factor de 0.18 per la presència de retardants i que l'emissivitat de la flama no es veu afectada per la presència de retardants. Aquests resultats indiquen que la presència de retardant redueix la intensitat del front de flames fonamentalment perquè es redueix la quantitat de calor efectivament alliberada per unitat de massa de combustible, més que perquè les propietats radiatives de la flama es canviïn. / Every year, thousands of hectares of forest are destroyed by wildland fires. It is necessary to investigate the mechanisms that influence the ignition and propagation of wildland fires in order to successfully devise strategies for fighting wildland fires and to establish plans for managing forest areas or grasslands. Researchers have been formulating models to describe surface fires and, to a lesser extent, crown fires, for more than sixty years. However, these models have a significant shortcoming: none of them has been developed for use as a tool to predict fire behavior after indirect attack operations with long-term retardants. Furthermore, most of the work done to date on long-term retardants has been with the goal of evaluating these products for commercial purposes.The goal of the present study was to improve knowledge of the effects of long-term retardants on the spread of forest fires. Retardants' effects on fire intensity were quantified for varying fire situations (no-slope/no-wind, upslope, upwind), together with retardants' effects on the heat of combustion of the fuel and flame emissivity. Assessing how these last two parameters change due to the presence of retardants on the fuel is a first step towards including the effects of indirect attack operations with long-term retardants in propagation models. We found that the presence of retardants reduced fire intensity by a factor of 0.8 under the experimental conditions tested in this study. The amount of heat effectively released during flaming combustion under the presence of retardants was observed to decrease by a factor of 0.18 in comparison with untreated samples and flame emissivity was observed to be unaffected by the presence of retardants. These results indicated that the presence of retardants reduces fire intensity primarily by reducing the amount of heat effectively released per unit mass of fuel, rather than by affecting the radiation properties of the flames.

Brominated flame retardants is a group of compounds present in numerous types of materials in our surroundings. Although their purpose is to slow the progression of a fire, many has been shown to be toxic to the environment. Novel brominated flame retardants have been introduced to the market as old ones have been removed. Reliable methods are crucial to be able to monitor how the novel brominated flame retardant spread and accumulate in the environment. To achieve this, a method validation of a cleanup method using multilayer silica followed by analysis by atmospheric pressure gas chromatography coupled to tandem mass spectroscopy was performed. This method had been previously used for polybrominated diphenyl ethers and the aim was to see if it could be used for analysis of novel brominated flame retardants as well. Spiking experiments showed generally good results, with recoveries of the native compound ranging from 40% to 174%. To apply the method on real matrix samples, eight samples of osprey eggs and five samples of adipose tissue of ringed seal was analyzed. Several novel brominated flame retardants were found, most abundant being the methoxylated polybrominated diphenyl ethers. Dominant congener was 2'-Methoxy-2,3',4,5'-tetrabromodiphenyl ether (2PMBDE#68) followed by 6-Methoxy-2,2',4,4'-tetrabromodiphenyl ether (6PMBDE#47), 5-Methoxy-2,2',4,4'-tetrabromodiphenyl ether (5PMBDE#47) and 5-Methoxy-2,2',4,4',6-pentabromodiphenyl ether (5PMBDE#100) with concentrations ranging from &lt;0,13-13 ng/g lipid weight in osprey eggs and &lt;0,003-249 ng/g lipid weight in ringed seal blubber. Also 1,2-Bis(2,4,6-tribromophenoxy)ethane and pentabromobenzene were found in both osprey eggs and ringed seal blubber. Hexabromobenzene was found in ringed seal blubber and 2,3,5,6-tetrabromo-p-xylene was identified in osprey eggs. / Bromerade flamskyddsmedel är en grupp ämnen närvarande i många olika typer av material i vår omgivning. Även om deras syfte är att bromsa förloppet vid en eldsvåda har många visat sig vara toxiska för miljön. Nya bromerade flamskyddsmedel har kommit ut på marknaden i takt med att gamla tagits bort. Pålitliga metoder är nödvändiga för att övervaka hur nya bromerade flamskyddsmedel sprids och ackumulerar i miljön. För att uppnå detta validerades en metod bestående av flerskiktskiseldioxid och analys med atmosfärstryck-gaskromatografi kopplat till tandem-masspektroskopi. Denna metod hade tidigare använts för analys av polybromerade difenyletrar och målet var att undersöka om samma metod kunde användas för analys ad nya bromerade flamskyddsmedel. Spikning gav generellt goda resultat - utbytet för de nativa ämnena var mellan 40% och 174%. För att pröva metoden på prov med riktigt matris analyserades åtta prov med fiskgjuseägg och fem prov med späck från vikare. Flera nya bromerade flamskyddsmedel hittades, mest förekommande var de metoxylerade polybromerade difenyletrarna. Dominerande kongen var 2'-metoxy-2,3',4,5'-tetrabromodifenyleter, följt av 6-metoxy-2,2',4,4'- tetrabromodifenyleter, 5-metoxy-2,2',4,4'- tetrabromodifenyleter och 5-metoxy-2,2',4,4',6- pentabromodifenyleter i koncentrationer från &lt;0,13-13 ng/g lipidvikt (fiskgjuseägg) och &lt;0,003-249 ng/g lipidvikt (sälspäck). Även 1,2-bis(2,4,6-tribromofenoxy)etan (fiskgjuseägg och sälspäck), pentabromobensen (fiskgjuseägg och sälspäck), hexabromobensen (sälspäck) och 2,3,5,6-tetrabromo-p-xylene (fiskgjuseägg) identifierades.

The occurrence of chemical contaminants in the environment is one of the key issues the world isfacing today. Special effort has been put on the screening of endocrine disrupting compounds(EDCs), substances that have been shown to have adverse effects on the endocrine system. EDCs are mainly found in pharmaceuticals and personal care products (PPCPs), but also other products covering almost all categories of our daily life. EDCs can be both organic, such as the persistent organic pollutants (POPs), and inorganic, e.g. heavy metals. Today, all kinds of EDCs are currently being investigated on a large scale. Two EDC sub-categories that have gained increased public attention during the last years are organic flame retardants (FRs) and per- and polyfluoroalkylated substances (PFASs). Both categories have shown to be bioaccumulating, persistent and toxic, which has led to banning of several substances in both categories. However, as both FRs and PFASs are considered to be emerging POPs, their fate and behaviour in the environment are still in great need of research. FRs and PFASs often end up in surface waters due to their disinclination of getting removed in waste water treatment plants (WWTPs) and their persistence. Thus, the objective of this project was to provide a snapshot of the current situation of FRs and PFASs in Swedish rivers, including both smaller streams and bigger rivers. Grab water samples were taken at 25 sites for FRs and 44 for PFASs in rivers all over Sweden. The results showed that sparsely populated areas such as the northern part of Sweden generally showed lower concentrations of PFASs in the water than the southern part did. The summarised concentrations of FRs ranged from 37 ng L-1 to 4.6 μg L-1, and from 0.59 ng L-1 to 59 ng L-1 for the detected PFASs, which was in good comparison to previous studies carried out on surface water in Europe. The percentile composition, the so-called fingerprint, showed significant differences between the southern part and the northern part for both FRs and PFASs, but also great similarities between some of the rivers with the highest measured PFASs concentrations. The highest loads of both FRs and PFASs were detected in Delångersån, which is one of the smaller rivers screened and likely to be affected by a nearby industrial point source. The European environmental quality standard of 0.65 ng L-1 of perfluorooctane sulfonic acid (PFOS) was exceeded in 12 of all 44 sampled rivers.

A novel method for determination of tetrabromobisphenol-A (TBBPA), was developed using gas chromatography-negative ion chemical ionization-mass spectrom- etry (GC-NCI-MS). Samples of municipal wastewater treatment plant (WWTP) influent were analyzed for TBBPA. Levels ranged from 1 to 41 ng/L, with an average of 20 ± 14 ng/L. Matrix effects were shown to be 30 ± 17 % in the influent and -30 ± 11 % in membrane permeate. The method limit of quantitation was 0.1 ng/L TBBPA. Sorption of TBBPA to fresh mixed-liquor suspended solids (MLSS) from a membrane bioreactor (MBR) were studied. In a kinetic study, sorption was found to be essentially complete after 12 hours of exposure to MLSS. Log Koc and log Kd were measured at 4.7 ± 0.8 and 1.9 ± 0.8 respectively (n = 22). These values were much higher than modelled estimates based on Kow (p ≥ 0.05), and higher than modelled estimates based on Kow and pKa (p ≥ 0.05). Data was successfully modelled using the Freundlich isotherm, having a Kf value of 8.5 and an n value of 1.7. TBBPA adsorbed to borosilicate glassware, with a wall-loss coefficient (Kw) of 0.15 ± 0.1 (n ≥ 3). TBBPA levels in WWTP influent varied from 13 to 29 ng/L while effluent concentrations varied from 0 to 2.2 ng/L over the same period. Three pilot-scale membrane bioreactors (MBRs) removed less TBBPA during the same time period, though MBR removal was also significant (p ≥ 0.05). Increasing MBR sludge residence time (SRT) increased removal at the 86 % confidence interval (p = 0.14). A nitrifying MABR was shown to remove TBBPA significantly when spiked with ammonia and TBBPA (p ≥ 0.05), showing that nitrifying bacteria can degrade TBBPA. An MABR hollow fibre was found to adsorb TBBPA. Various soluble microbial products (SMP) were studied from MBRs fed munici- pal influent. Using current measurement practices, SMP were shown to be sensitive to matrix effects. Use of the standard addition technique (SA) can compensate for this. Measurements using SA showed SMP degrades rapidly during storage in the fridge and due to freezing. SA was also used to compare commonly used SMP extraction techniques, and showed that extraction method influences recovery.

Summary Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants. The addition of these chemicals to electrical and electronic equipment, building materials, carpet and textiles reduces flammability and therefore harm and destruction caused by unwanted fire. These chemicals are now internationally ubiquitous in the environment and humans because of their increased usage and physical and chemical properties of persistence and lipophilicity. Although Australian data on both the concentrations and the sources and exposure pathways was limited, a preliminary study of PBDEs in 10 pools of human blood serum revealed that concentrations of PBDEs in Australia were comparatively higher than most countries with the exception of Canada and the USA. The aim of this project was to determine the concentrations of PBDEs in the Australian population and to examine the possible sources and pathways of exposure in humans. Experimental evaluation of PBDE exposure matrices included samples of: sediment (n=46), air (n=19), dust (n=19), surface wipes (n=10) and human milk (157 samples combined into 17 pools, n=10 individual samples); and the general population using human blood serum (10552 samples combined into 169 pools). With accumulating evidence regarding age differences in PBDE concentrations, the scope of this project was broadened to include a focus on infants and young children. This study found that PBDE contamination was widespread in the Australian environment and human population. In sediment, PBDEs were relatively low at the majority of sites with mean ± standard deviation and median ΣPBDE concentrations across all sites of 4707 ± 12580 and 305 pg g-1 dw, respectively. There were elevated concentrations found downstream of sewerage treatment plants; in areas dominated by industrial and urban land-use types; and in estuarine compared to freshwater environments. PBDEs were detected in air, dust and surface wipes. Concentrations on the whole were found to be higher indoors compared to outdoors and in offices compared to homes. ΣPBDE concentrations ranged from 0.5 -179 pg/m3 for homes and 15 - 487 pg/m3 for offices and at the two outdoor sites the concentrations were 1.7 and 6.8 pg/m3. PBDEs were detected on 9 out of 10 surfaces (e.g. television, refrigerator, DVD player) sampled and ranged from non-detectable to 5985 pg/cm2 while in dust, ΣPBDEs ranged from 87 - 733 ng/g dust in homes and 583 - 3070 ng/g dust in offices. PBDEs were detected in all individual and pooled samples of human milk and blood serum and the ΣPBDE and BDE-47 concentrations ranged from 5.5 to 103 and 0.6 to 55 ng/g lipid, respectively. There were no regional differences in concentrations in human milk or blood serum and in general PBDE concentrations were higher in males than in females. Although no temporal trend was apparent in samples of human milk or blood serum collected between 2002 and 2008, the ban on penta- and octa-BDE commercial products in several countries has only been in place since 2004. Hence, effects of the ban may not be reflected in human body burden for several years. The concentrations of PBDEs were found to be highest in young children aged 2 – 5 years of age where concentrations were up to 10 times greater than those detected in adults. Congener profiles for sediment, air, dust and surface wipes were mostly dominated by BDE-209. In human milk and serum, BDE-47 was dominant while BDE-209 contributed only 3% in human milk and was not determined in serum. Concentrations of PBDEs found in Australian human and environmental samples were lower than those reported from North America but higher than those reported from Europe and Asia. The results of modeling and the assessment of matched samples of human milk, indoor air and dust showed that body burden could be partly explained by exposure via food, air, dust and human milk as well as clearance (half-life) data. However, the higher than expected concentrations in young children indicated that there are likely to be missing sources and exposure pathways and/ or the clearance data is inaccurate. The results of this thesis provide baseline data on PBDE concentrations in Australia and will prove important for long term monitoring of the effect of changes in usage rates of these chemicals. It is important to understand the specific sources and exposure pathways of PBDEs in infants and young children in order to identify intervention methods whereby exposure to this vulnerable population can be reduced. In terms of the future use of PBDEs or other flame retardant chemicals, it is important that the risk-benefit ratio is regulated so that the minimization of human exposure and potential associated negative health effects is balanced with the reduction of harm caused by fire.

abstract: Consumption of seafood poses a substantial threat to global biodiversity. Chemical contamination found in both wild-caught and farmed seafood also presents significant health risks to consumers. Flame retardants, used in textiles, upholstery, plastics, and other products to reduce risk of fire-related injury, are of particular concern as they are commonly found in the marine environment and permeate the tissues of fish that are sold for consumption via multiple pathways. The widespread issue of fishery collapse could be alleviated by demonstrating to stakeholders that many unsustainable fish stocks are also unhealthy and mutually disadvantageous for both human consumers and the environment. To thoroughly investigate the confounding factors and contradictory signals enmeshed in the relationship between ecologically sustainable fisheries and flame retardant contamination, I examined the biological characteristics of regional fish stocks which drive both contamination and perceived sustainability. I found that the biological and spatial aspects of commonly consumed aquatic and marine species best predict contamination when compared with various indices of sustainability. My results confirm that knowledge of flame retardant toxicity will become increasingly more important to consumers because a high percentage of global populations rely on coastal seafood for subsistence, and although dispersal of chemical contamination is still a poorly understood phenomenon, fish harvested closer to land are likely to contain higher concentrations of potentially harmful chemicals. Because some of the same biological traits which facilitate the uptake of chemicals also contribute to how a species responds to fishing pressures, concern for private health increases public consideration for the conservation of species at risk. / Dissertation/Thesis / Masters Thesis Biology 2015

Os retardantes de chama bromados são substâncias utilizadas nos mais variados bens de consumo para aumentar sua resistência ao fogo e/ou altas temperaturas em casos de incêndio, aumentando assim, as chances de escape e reduzindo a gravidade das queimaduras. Para este fim os éteres difenílicos polibromados (PBDEs) representam a classe mais utilizada tendo em vista sua eficiência no controle da propagação da chama e seu baixo custo. Estes compostos se incluem entre os recentemente denominados contaminantes ambientais emergentes que apresentam uma carência de dados toxicológicos, principalmente em relação aos efeitos danosos e aos biomarcadores de exposição, além do potencial dano ao ambiente, sendo esta uma preocupação recente da comunidade científica. Pelo fato da mitocôndria ser reconhecida como a principal organela produtora de energia celular, além de exercer um papel fundamental na manutenção de inúmeras funções celulares, ela foi utilizada como modelo experimental para avaliar os efeitos dos congêneres de BDE- 100; -153; -154 e -209 na faixa de concentração de 0,1 ?mol/L a 50 ?mol/L. Nossos resultados mostram que os efeitos em mitocôndrias isoladas podem ocorrer em menores concentrações para os congêneres BDE-153; -154 (Hexa-BDE) e -209 (Deca-BDE) e em maiores concentrações para o BDE-100 (Penta-BDE). Desta forma, foi observado que os compostos possuem capacidade de interagir com membrana mitocondrial, induzir inchamento mitocondrial, desregular a homeostase cálcica e dissipar o potencial de membrana mitocondrial em concentrações diferentes, entretanto não são capazes de induzir estresse oxidativo na mitocôndria. Assim, os resultados indicam que a ação dos PBDEs sobre mitocôndrias pode ser um dos mecanismos de toxicidade desta classe de compostos. / The brominated flame retardants are substances used in various consumer goods to increase their fire resistance and / or higher temperatures in case of fire, thus increasing the chances of escape and reducing the severity of burns. To this end polybrominated diphenyls ethers (PBDEs) are the most used class in view of its efficiency in controlling the spread of flame and its low cost. These compounds are among the newly emerging environmental contaminants known to exhibit a lack of toxicological data, especially regarding the harmful effects and biomarkers of exposure and potential harm to the environment, which is a recent concern of the scientific community. Because the mitochondrion is recognized as the main energy-producing cell organelles, as well as play a vital role in the maintenance of many cellular functions, it was used as an experimental model to evaluate the effects of the congeners BDE-100 (Penta- BDE), -153, -154 (Hexa-BDE) and -209 (Deca-BDE), in concentration range ranging from 0.1 ?mol/L to 50 ?mol/L. The results show that the effects on isolated mitochondria may occur at lower concentrations for the BDE-153, -154 and -209 and high concentrations to the BDE-100. Thus, it was observed that the compounds have the ability to interact with mitochondrial membrane, inducing swelling, dysregulation of calcium homeostasis and dissipation of membrane potential at different concentrations, however they cannot change factors related to oxidative stress in mitochondria. Furthermore, the induction of mitochondrial swelling, and added significant depletion of ATP levels may contribute to the toxic effects observed. Thus, we conclude that the action of PBDESS on mitochondria is one of the mechanisms of toxicity of this class of compounds.

Fire presents a great risk to humans and their possessions. Polymeric compounds are highly flammable and compounds are added to increase their fire resistance. These additives are referred to as flame retardants. Intumescent flame retardants are systems that form a carbon rich foam on the surface of the polymer during thermal degradation. A new field of metal catalysed intumescence is discussed in this document. The influence of both the metal ion and organic backbone of polyhydroxylcarboxylic acid metal salts was studied. The intumescence and foaming properties of selected salts were studied in more detail. Gluconic acid proved to be the best intumescent and showed the best combination of carbon char yield, foam structure and volume, stability and open flame characteristics. As a general rule of thumb, the char volume and structure improved with an increased number of hydroxyl groups in the compound. Carbon char yield increased with an increase in the number of hydroxyl groups for a constant number of carbons in the complex. The number of acid groups in the compound played a lesser role in intumescence. Most metal complexes catalyse intumescent decomposition of polyhydric compounds such as polyhydroxylcarboxylic acids and pentaerythritol. The reduction in the volatilisation losses implies that the metal cations catalyse carbonisation reactions in the polyhydroxyl compound. Unfortunately, the resultant carbon-foams are unstable: the metal residues also catalyse the further oxidative degradation of the char. The low thermal stability of the compositions tested, as well as the afterglow effect makes them unsuitable for use as flame retardant additives in plastics. From the studies of the different metal complexes with acetylacetone and gluconic acid, it was concluded that the calcium ion exhibited the most promise. When pyrolysed in air with an open gas flame or in a furnace, calcium gluconate monohydrate produces voluminous foam. The foam is of a closed cell structure, densely packed and has no mechanical strength. The cell walls are very thin (5 to 50 nm) and the cells are between 50 µm and 200 µm in size. If the sample is compressed before heating, the resultant foam produced during pyrolysis is less voluminous than that of the loose powder. The BET surface area of the calcium gluconate monohydrate foamed at 300°C for 5 min. is 16.0 m2/g. The foam produced after 5 min heating at 300°C has a thermal conductivity similar to standard polystyrene foam. Adding leached silica to the calcium gluconate monohydrate increases mechanical strength of the foam, but influences the foam volume negatively. The optimum silica level was calculated to be 1:1 gluconate to silica on a mole ratio (11.8% SiO2 by mass). The mechanical strength of the foam can also be increased with the addition of expandable graphite. The graphite has a lesser influence on the foam volume than the silica, but also reduces the foam volume. However, the addition of the expandable graphite gives the sample more .opening. force, as the foam volume of a compressed sample pyrolysed, is similar to that of the heated loose powder. Calcium gluconate monohydrate starts to degrade at 120°C, losing its crystal water and shows a mass loss of 4% at 180°C. The exothermic peak (shown in the DSC/TGA data) associated with the metal catalysed carbon oxidation (afterglow) is observed at 570°C in air. For the calcium gluconate monohydrate the transition from CaCO3 to CaO occurs above 650°C in air. It has been shown that the foaming of polyhydroxylcarboxylic acids is due to the formation of water vapour during degradation. For calcium gluconate monohydrate, foaming starts due to the loss of crystal water and is continued by the loss of hydroxyl groups as water. The bulk of the foaming is due to the second reaction. It has been shown that compounds with crystal waters produce a more voluminous and lower density foam. The foam is an amorphous carbon rich residue. The molecular mass of the carbon residue increases up to a heating temperature of 300°C. This implies that the carbon residue crosslinks during formation, forming a stretchable cell wall for the foam. Compounds with a .free. hydroxyl group at the end of the carbon chain produce a foam of larger volume and lower density. This supports the crosslinking theory. The foam produced when calcium gluconate monohydrate is heated for 5 min at 300°C in air is of very low density . 2.5 kg/m3 based on residual mass. The density of the calcium gluconate monohydrate pyrolysed at 1000°C for 5 min in air yields a CaO with a density of 20 kg/m3 . This implies that the high temperature pyrolysis of calcium gluconate can produce an inorganic oxide of low bulk density and possible high specific surface area. The BET surface area of CaCO3 from the gluconate pyrolysed at 600°C is ~ 12 m2 /g. An intumescent coating containing calcium gluconate monohydrate, leached silica and expandable graphite as a system was prepared and compared to commercial formulations. This gluconate based system was at least as efficient as the commercial formulations when painted on balsa wood planks or aluminium plates. On cardboard sheets it did not perform as well as the commercial systems. More work should be done to overcome the afterglow effect observed with metal- based intumescent systems. The crystal structure of calcium gluconate monohydrate should be determined as to understand the decomposition better. It is unclear whether the decomposition is catalysed inter- or intramolecularly. / Thesis (PhD(Chemical Engineering))--University of Pretoria, 2005. / Chemical Engineering / unrestricted