EAPA Asphalt at the Workplace
International Review of Occupational Health and Safety related to the asphalt* industry
Following an article which appeared early 1997 in the World Highways Magazine the asphalt and bitumen industry have provided the following text on occupational health and safety to provide a short update of current work that is being carried out at an international level**. This text, which is offered to the World Highways Magazine as an article, explains why this work is being done and provides contact points to allow readers to obtain more information if required.
Working conditions for the asphalt industry workers have always been a major attention point for the industry and significant improvement has been made over the years. There are obvious hazards arising from using heavy process plant and machinery and where the actual task of construction often has to be under taken whilst traffic continues to flow in close proximity. There are also important hazards which arise because the materials utilised for flexible roads are manufactured, stored and delivered at high temperatures to avoid the material going solid. Thus a principle focus of attention has been to ensure that any risks associated with these high temperatures are well understood and that workers and the general public are protected by the adoption of proper working practices.
The high temperatures are needed because of the properties of the bitumens (asphalt*) used in manufacturing flexible roads. Refined bitumens are a complex combination of hydrocarbon compounds obtained as the residuum of the refinery processing of crude oil where the temperatures exceed 350 degrees centigrade.
In Europe, paving grade bitumens are normally maintained for storage and delivery at temperatures of between 150 and 200 degrees centigrade.
In the USA for paving grades the range of typical temperatures is between 150 degrees centigrade temperature and 175 degrees centigrade.
These temperatures are maintained throughout the process of manufacture, delivery and application of asphalt mixes. At these temperatures a relatively small quantity of fumes is generated and therefore for both economic and environmental reasons the material is normally kept in closed vessels or covered wagons. During laying operations the asphalt mix is exposed to the air and emissions of small quantities of fumes will take place until the asphalt cools after compaction. Measurements of these emissions have always indicated that they are very low and below the current occupational health standards.
After cooling and under all normal environmental conditions refined bitumens (asphalts*) are not a risk to humans. From the occupational point of view the situation is different because of the high temperatures involved. The principle occupational hazards which industry workers face are from severe thermal burns and the potential for fire and explosion.
Also if proper working practices are not followed regarding temperature control then overheating can cause a change to the chemical composition of the fume.
Although these hazards are well known the occupational risk to asphalt workers arising from asphalt fumes has been the focus of attention and scientific study for a long time because the chemistry of refined bitumens is very complex and the melting points and boiling points of individual compounds contained are very high which does not allow for easy chemical analysis. Therefore there are no easy ways of determining the answers to all the relevant questions on health and safety, in particular bitumens are known to contain very small “trace” concentrations of PAC’s (Polycyclic Aromatic Carbon).
In order to resolve this issue the occupational risk to asphalt workers arising from asphalt fumes have been the focus of attention and scientific study for a long time particularly in Europe and in North America. Comprehensive bibliographies have been compiled by IARC [International Agency for Research on Cancer] and CONCAWE [The oil companies’ organisation for the Conservation of Clean Air and Water in Europe] NIOSH [National Institute for Occupational Safety and Health] and ACGIH [American Conference of Governmental Industrial Hygienists].
A further dimension to the health and safety studies has occurred in the area of Binder Innovation. Asphalt mix performance with conventional bitumen binders seems to be hitting a performance ceiling which can only be overcome by using modified binders. Not surprisingly therefore, the range and use of modified binders is widening to meet more severe user requirements. A major market requirement is that modified binders must maintain all the existing benefits of asphalt pavements as well as giving the additional benefits. It is no use to get better performance in one particular property at the expense of other important properties or at the expense of health and safety and environmental considerations.
In Europe the occupational risks to asphalt workers arising from asphalt fumes** have been the focus of attention and scientific study for a long time. The most recent initiative to pro-actively address this issue started in 1992 when the industry commissioned a study from the International Agency for Research on Cancer [IARC] in Lyon to evaluate and validate existing epidemiology studies. The initiative was jointly taken by the European Asphalt Pavement Association [EAPA], the European Bitumen Association [Eurobitume] and the oil companies’ European organisation for Environment, Health and Safety [CONCAWE].
In 1993, the European Commission, represented by the Technical Progress Group for the European Commission Directive on Classification and Labelling of Substances considered how to classify bitumens and deferred a decision on the carcinogenicity of bitumens awaiting further information from IARC. The Group did not consider it necessary to make a precautionary classification. In 1994, IARC reported in the scientific literature that existing studies at that date and time could not be used directly or indirectly to address questions about the possible carcinogenicity of bitumen fumes [American Journal of Industrial Medicine 26:721-740 (1994)]. As existing studies could not be used for the proper assessment of the occupational risks to asphalt workers***, IARC recommended further that a nested case control epidemiological study is feasible in Europe among workers to establish risk factors. Based on this recommendation and the commitment of the European industry to actively look for further data to fill existing gaps, a full scale epidemiological investigation in 7 European countries among over 45000 workers was designed in 1995. In 1996 the study was started.
EAPA, Eurobitume and CONCAWE believe that this study offers the best means of resolving the concerns which have been expressed about possible occupational risks for asphalt workers. Meanwhile the industry has established together with 4 main manufacturers of paving equipment a research proposal for the European Brite Euram project in April 1996 to redesign the existing paver. Major emphasis included in this proposal is based on the significant improvement of the health and safety situation of the entire crew around the paver.
Retrofits are continuously adapted to the pavers and the working practice, to improve the working environment and to comply with new European directives on the European Community marking of equipment and on the protection of workers against chemical agents and physical agents.
The industry is communicating frequently on these subjects and HSE issues were given an open forum at the 1st Eurasphalt & Eurobitume Congress held in May 1996. Openness is a sign of a healthy industry and a clear sign of the confidence of Eurobitume and EAPA in bringing such issues into the public domain. In the same way the industry strives to ensure that all work on HSE issues is submitted to rigorous peer review before conclusions are accepted. The same rigour and professionalism as is applied to all research and development carried out in the industry.
The Eurasphalt & Eurobitume Congress gave up to date information on the above subjects. Another of the issues addressed was the reported cases where it has been observed at a few job sites that fumes have caused irritation effects. Studies have been carried out to find out the cause. One of the major conclusions was that fuming levels from properly formulated polymer modified bitumens are no greater than for conventional bitumens. This conclusion is very much in line with the findings of other work in Australia and the USA where poor selection of lighter distillate fluxing agents, not the bitumen or the polymers, was found to be causing fuming problems. Here again the design of equipment as a precaution against irritation effects from exposure to fume caused by over-heating or poor selection of materials is seen as helpful. Nevertheless in Europe as elsewhere good working practices remain the best way to prevent any discomfort to workers.
In the United States, the AIEOC (Asphalt Industry Environmental Oversight Committee) is involved in several studies to provide further information on the potential effects of exposure to asphalt fumes.
Recently an agreement has been reached between NIOSH, FHWA(Federal Highways Administration), Labor Unions, Paving Equipment Manufacturers and Asphalt Contractors to install engineering controls on new asphalt pavers to improve the general working environment of the paving crews.
Working conditions for the asphalt industry workers have always been a major attention point for the industry and significant improvement has been made over the years.
Current health and safety knowledge does not justify classifying either bitumen or bitumen fumes as being hazardous to man. Nevertheless because of the complexity of the materials being used there still exist scientific uncertainties which do not allow a complete occupational health assessment.
A number of studies are under way to address gaps in the existing evidence which will add considerably to scientific understanding of the key existing health effects studies on asphalt fumes Current occupational exposures to asphalt fumes are well controlled and the industry is investigating further reduction
Further information can be obtained from the offices of:
Asphalt Institute 6917 Arlington Rd., STE 210, Bethesda, MD 20814 Tel: 301 656 5824; Fax: 301 656 5825
EAPA Straatweg 68, 3621 BR Breukelen, P.O. Box 175, 3620 AD Breukelen, The Netherlands. Tel: +31 (0) 346 266868; Fax:+31 (0)346.263505
Eurobitume Madou Plaza (25th Floor), Place Madou 1, 1210 Brussels, Belgium. Tel: 322 226 19 49; Fax: 322 226 19 40
NAPA NAPA Building, 5100 Forbes Boulevard, Lanham, Maryland 20706-4413 Tel: (301) 731 4748; Fax: (301) 731 4621
* In Europe "asphalt" refers to "asphalt mix" and "bitumen" to the US phrasing "asphalt cement".
** An asphalt worker is someone involved in the production or application of bituminous mixtures used in road paving operation.
German Translation of Conclusions.
Die Arbeitsbedingungen für Asphaltarbeiter waren für die betreffende Industrie immer Gegenstand grosser Aufmerksamkeit und wesentliche Verbesserungen wurden im Laufe der Jahre erreicht.
Der derzeitige Erkenntnisstand bezüglich Gesundheit und Arbeitssicherheit rechtfertigt weder eine Einstufung von Bitumen noch von Bitumendämpfen als gefährlich für Mensch oder Umwelt.
Dennoch sind wegen der stofflichen Komplexität des verwendeten Materials noch nicht alle diesbezüglichen Fragen wissenschaftlich geklärt, so dass eine vollständige Bewertung der arbeitsplatzbezogenen Gesundheitsfragen noch nicht möglich ist.
Um noch vorhandene Lücken im derzeitigen Kenntnisstand zu schliessen, sind mehrere Studien in Arbeit; sie werden einen wesentlichen Beitrag leisten für das wissenschaftliche Verstädnis der vorhendenen grundlegenden Arbeiten über gesundheitliche Auswirkungen von Asphaltdämpfen.
Die gegenwärtigen Arbeitsplatzbelastungen werden aufmerksam beobachtet und die Industrie verfolgt Möglichkeiten weiterer Reduzierungen.
Résumé en français
Les conditions de travail du personnel de l’industrie des enrobés bitumineux ont toujours constitué une préoccupation prioritaire pour cette industrie et des améllorations significatives ont été apportées au fil des années.
Les connaissances actuelles en matière de santé et de sécurité ne justifient pas que les bitumes ou les fumées de bitumes soient classés comme étant dangereux pour l’homme.
Néanmoins a cause de la nature complexe des matériaux utilisés, il subsiste encore quelques incertitudes scientifiques qui ne permettant pas de disposer d’une évaluation compléte des questions de santé professionelle.
Plusieurs études en cours permettront de compléter les connaissances actuelles et contribueront de façon considérable à améliorer la compréhension scientifique des points clefs relatifs a l’incidence des fumées de bitume sur la santé.
Les expositions courantes des travailleurs aux fumées de bitume sont bien contrôlées et l’industrie étudie les possibilités de les réduire davantage.
Spanish translation of summary
La condiciones de trabajo de los trabajadores de la industria de las mezclas bituminosas han sido siempre una preocupación prioritaria para esta industria y se han hecho mejoras significativas a lo largo de los años.
El conocimiento actual sobre la seguridad y la salud no justifica clasificar los betunes o los humos de betún como peligrosos para el hombre.
Sin embargo, a causa de la complejidad de los materiales que se utilizan, subsisten todavía incertidumbres científicas que no permiten una completa evaluación de la salud ocupacional.
Están en marcha una serie de estudios que completarán los conocimientos actuales y contribuirán considerablemente a mejorar la comprensión científica de los puntos claves relativos a la incidencia de los humos de betún sobre la salud.
Las actuales exposiciones ocupacionales a los humos de asfalto están bien controladas y la industria está estudiando la posibilidad de llevar a cabo nuevas reducciones.