Hazard and risk assessment of industrial chemicals in the occupational context in Europe: some current issues

Letter re: Regulatory toxicology approaches in workplaces of Iran

The objective of establishing occupational exposure limits (OELs) is to utilize them as a risk management tool, ensuring the protection of workers' health and well-being from hazardous substances present in the workplace. To regulate and develop an OEL, it is essential to conduct toxicological studies on both animals and humans, to determine the dose-response relationship for each chemical compound, and to determine whether the dose-response relationship is linear or non-linear. Because the OELs suggested by different organizations or countries are just the result of their scientific methods, knowledge, and judgment, this does not confirm the applicability in other countries. Therefore, it is not scientific and logical to imitate the permissible limits recommended in Western countries. In most Western Asian nations, there is a significant difference in the suggested OEL levels between the reference organizations, and in assessing and managing a specific situation's risk, using any of the proposed OELs can lead to contradictory results. Suggestions for the development and improvement of the basics of determining the OELs for chemical pollution in West Asian countries have been made.

Industry Derived Occupational Exposure Limits: A Survey of Professionals on the Dutch System of Exposure Guidelines

The Netherlands’ system for occupational exposure limits (OELs) encompasses two kinds of OELs: public and private. Public OELs are set by the government. Private OELs are derived by industry and cover all substances without a public OEL. In parallel, the regulation concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) has introduced an exposure guidance value similar to the OEL, namely the Derived No-Effect Level (DNEL) for workers’ inhalation exposure. This study aimed to investigate issues encountered by occupational health professionals regarding private OELs, and how they perceive the DNELs for workers in relation to private OELs. Towards this aim, we sent out a web-based questionnaire to the members of the Dutch professional organization for occupational hygienists (Nederlandse Vereniging voor Arbeidshygiëne [NVVA], n = 513) and to members of the Dutch professional organization for safety engineers (NVVK, n = 2916). Response rates were 27% (n = 139) and 7% (n = 198), respectively. More occupational hygienists (59%) than safety engineers (17%) reported to derive private OELs themselves. Our respondents reported several challenges with the derivation of private OELs. Fifty-one percent of the occupational hygienists and 20% of the safety engineers stated to see a role of REACH Registrants’ worker DNELs as private OELs. However, more than half of our respondents were undecided or unfamiliar with worker DNELs. In addition, stated opinions on where worker DNELs fit in the hierarchy of private OELs varied considerably. To conclude, both these professional groups derive private OELs and stated that they need more guidance for this. Furthermore, there is a lack of clarity whether worker DNELs may qualify as private OELs, and where they would fit in the hierarchy of private OELs.

Occupational Risk Factors and the Relationship of Smoking with Anxiety and Depression

OBJECTIVES

The aim of the present study was to evaluate the relation of smoking with anxiety and depression in workers who were exposed to occupational risk factors. For this purpose, working time, smoking status, nicotine dependence, and respiratory functions of the workers who were exposed to physical and/or chemical harmful substances were evaluated and the presence of anxiety/depression was investigated.

MATERIAL AND METHODS

Male workers who were exposed to occupational risk factors such as solvents, heavy metals, and dust and visited the outpatient clinic for occupational diseases within a one-year period were included. Pulmonary Function Test and Fagerström Test for Nicotine Dependence were performed. Anxiety and depression statuses of the workers were assessed using the Hospital Anxiety and Depression Scale.

RESULTS

The mean age of 665 male workers was 45 y (range, 38-48 y), and they were most commonly exposed to solvents (45.9%), followed by heavy metal fume/dust (20.9%). Of the workers, 252 (37.9%) had anxiety, 294 (44.2%) had depression, and 171 (25.7%) had both. More than half of the workers in each occupation/exposure group were smokers. Respiratory complaints were present in 34% of the workers. According to the regression analysis, the presence of respiratory system complaints was found to be a significant risk factor for anxiety, depression, and anxiety plus depression.

CONCLUSION

In conclusion, smoking and anxiety/depression were found to be the conditions affecting more than half of the workers with occupational exposure.

Assessment of the potential human health risks from exposure to complex substances in accordance with REACH requirements. "White spirit" as a case study

The European chemical control regulation (REACH) requires that data on physical/chemical, toxicological and environmental hazards be compiled. Additionally, REACH requires formal assessments to ensure that substances can be safely used for their intended purposes. For health hazard assessments, reference values (Derived No Effect levels, DNELs) are calculated from toxicology data and compared to estimated exposure levels. If the ratio of the predicted exposure level to the DNEL, i.e. the Risk Characterization Ratio (RCR), is less than 1, the risk is considered controlled; otherwise, additional Risk Management Measures (RMM) must be applied. These requirements pose particular challenges for complex substances. Herein, "white spirit", a complex hydrocarbon solvent, is used as an example to illustrate how these procedures were applied. Hydrocarbon solvents were divided into categories of similar substances. Representative substances were identified for DNEL determinations. Adjustment factors were applied to the no effect levels to calculate the DNELs. Exposure assessments utilized a standardized set of generic exposure scenarios (GES) which incorporated exposure predictions for solvent handling activities. Computer-based tools were developed to automate RCR calculations and identify appropriate RMMs, allowing consistent communications to users via safety data sheets.

Primary prevention of occupational asthma: identifying and controlling exposures to asthma-causing agents

BACKGROUND

Primary prevention of occupational asthma requires timely identification and regulation of asthma-causing agents.

METHODS

We examined 39 substances identified as causing allergic occupational asthma in the US to determine the basis for their identification and their regulatory status. We compared them with occupational asthmagens identified and regulated in the UK and Germany.

RESULTS

US regulatory agencies have not established consistent, evidence-based methods to identify and control exposures to substances that cause occupational asthma. Occupational asthmagens are identified primarily by non-regulatory US organizations, and most are not regulated to prevent asthma.

CONCLUSIONS

Implementing an evidence-based identification and regulatory process for occupational asthmagens will help to ensure primary prevention of occupational asthma in the US. This should include: establishing consistent identification criteria; publishing a list of occupational asthmagens; collecting use, exposure, and health effects information on asthma-causing substances; requiring medical surveillance and medical removal protection in addition to exposure limits; and stimulating development of safer alternatives.

Background, approaches and recent trends for setting health-based occupational exposure limits: a minireview

The setting of occupational exposure limits (OELs) are founded in occupational medicine and the predictive toxicological testing, resulting in exposure-response relationships. For compounds where a No-Observed-Adverse-Effect-Level (NOAEL) can be established, health-based OELs are set by dividing the NOAEL of the critical effect by an overall uncertainty factor. Possibly, the approach may also be used for carcinogens if the mechanism is epigenetic or the genetic effect is secondary to effect from reactions with proteins such as topoisomerase inhibitors, and mitotic and meiotic spindle poisons. Additionally, the NOAEL approach may also be used for compounds with weak genotoxic effect, playing no or only a minor role in the development of tumours. No health-based OEL can be set for direct-acting genotoxic compounds where the life-time risks may be estimated from the low-dose linear non-threshold extrapolation, allowing a politically based exposure level to be set. OELs are set by several agencies in the US and Europe, but also in-house in major chemical and pharmaceutical companies. The benchmark dose approach may in the future be used where it has advantage over the NOAEL approach. Also, more attention should be devoted to sensitive groups, toxicological mechanisms and interactions as most workplace exposures are mixtures.

Assessment of potential hazards during the process of house building in Estonia

The aim of this study was to evaluate new working conditions in the construction industry in Estonia. Three construction sites were investigated: a dwelling house at the stage of renovation, a warehouse at the stage of excavation and preparation work, and a hotel, where we examined the working conditions of the finishers. Microclimate: air temperature, relative humidity and air velocity were determined at every workplace. Full-shift personal exposure measurements of dust and gas exposure were performed among 97 construction workers in breathing zone air. The concentration of lead in the air was analysed by AAS. Vapours of benzene, styrene and toluene concentrations were determined by gas chromatography. The noise level was measured with the help of the sound-level meter at every workplace. All microclimatic indices were sometimes below or above exposure standards for indoor work. High levels of airborne dust and increased concentrations of lead were observed during repair work. Low concentrations of organic solvents in the air were determined when using paints and some synthetic substances. The noise level exceeded the permitted limit when an excavator and powerful electric appliances were used. A questionnaire determined the prevalence of subjectively experienced musculoskeletal strain in 30% of workers. The working conditions in the construction industry in Estonia are approaching European level. However, it is necessary to improve working conditions permanently by the use of new harmless materials, personal protective equipment, and through influencing worker health by permanent education and medical watch. We consider that questionnaires are very important in the control of the work environment, in subjective health assessments, and as a source of useful proposals to improve working conditions.

Risk migration and scientific advance: the case of flame-retardant compounds

It is a common experience that attempts to mitigate a risk lead to new risks, and that risks formerly thought to be of one kind become another kind as technical knowledge evolves. This phenomenon of risk migration suggests that we should take processes over time, rather than specific risks or specific technologies, as a unit of analysis. Several of our existing models of the social management of risks-such as that of social risk amplification-are process models of a kind but are still oriented around the playing out of a particular event or issue. A case study of risk in a group of flame-retardant compounds was used as the basis of a grounded, exploratory analysis of migration processes, the phenomena that influence them, and their consequences. This illustrated how migration naturally occurs from risks that are understood, in which risk bearers have at least some agency, to risks that are not understood and not capable of being influenced by risk bearers. It illustrated how the simultaneous improvement in measuring technology, which detects potential toxins at increasingly small concentrations, combines with intuitive models that ignore concentration to produce conditions likely to generate anxiety. And it illustrated how pressure groups and commercial interests exploit this effect. It also showed how migration makes precautionary action problematic, and how more generally it tends to undermine a society's capacity to cope with risk.

Relationship between chemical structure and the occupational asthma hazard of low molecular weight organic compounds

AIMS

To investigate quantitatively, relationships between chemical structure and reported occupational asthma hazard for low molecular weight (LMW) organic compounds; to develop and validate a model linking asthma hazard with chemical substructure; and to generate mechanistic hypotheses that might explain the relationships.

METHODS

A learning dataset used 78 LMW chemical asthmagens reported in the literature before 1995, and 301 control compounds with recognised occupational exposures and hazards other than respiratory sensitisation. The chemical structures of the asthmagens and control compounds were characterised by the presence of chemical substructure fragments. Odds ratios were calculated for these fragments to determine which were associated with a likelihood of being reported as an occupational asthmagen. Logistic regression modelling was used to identify the independent contribution of these substructures. A post-1995 set of 21 asthmagens and 77 controls were selected to externally validate the model.

RESULTS

Nitrogen or oxygen containing functional groups such as isocyanate, amine, acid anhydride, and carbonyl were associated with an occupational asthma hazard, particularly when the functional group was present twice or more in the same molecule. A logistic regression model using only statistically significant independent variables for occupational asthma hazard correctly assigned 90% of the model development set. The external validation showed a sensitivity of 86% and specificity of 99%.

CONCLUSIONS

Although a wide variety of chemical structures are associated with occupational asthma, bifunctional reactivity is strongly associated with occupational asthma hazard across a range of chemical substructures. This suggests that chemical cross-linking is an important molecular mechanism leading to the development of occupational asthma. The logistic regression model is freely available on the internet and may offer a useful but inexpensive adjunct to the prediction of occupational asthma hazard.