Comparison of South African skin and sensitisation notations with those of other countries

ORIGINAL RESEARCH                    PEER REVIEWED

 
JL du Plessis,1 FC Eloff,1   PJ Laubscher,1  MN van Aarde,1     A Franken1
 
1School of Physiology, Nutrition and Consumer Sciences,
Faculty of Health Sciences,
North-West University
 
All authors are SAIOH members
 
Corresponding author:
Johan L Du Plessis,
School of Physiology, Nutrition and Consumer Sciences,
Faculty of Health Sciences,
North-West University.
Private Bag X6001,
Potchefstroom. 2520
Tel: +27 (0)18 299 2434
Fax: +27 (0)18 299 2433
E-mail: Johan.DuPlessis@nwu.ac.za
 

Abstract
South African skin notations listed in the Regulations for Hazardous Chemical Substances (RHCS) and Mine Health and Safety Regulations (MHSR) were compared to those of selected other developed countries in order to ascertain the assignment criteria and use of these notations relative to those of other countries. Skin notations in the RHCS and MHSR had a mean agreement of between 42.9% and 45.8% with other countries, while agreement for sensitisation notations was only 3.6% between countries. As with many other countries there is a lack of frequent review and updates of these notations. Thus, there is an urgent need to develop and implement a strategy which will ensure frequent revision of assignment of notations accompanied by accessible supporting documentation. Adoption of the USA’s National Institute for Occupational Safety and Health skin ­notation criteria is recommended, whereby substances may be assigned with multiple descriptive skin notations. The development of similar sensitisation notation criteria whereby the route of exposure is indicated is also recommended.

Key words: skin notation, sensitisation notation, comparison, countries


 
 
Introduction
In South Africa, occupational exposure limits (OELs) and skin and sensitisation notations for the general industry (non-mining) are published in the Regulations for Hazardous Chemical Substances (1995)1 under the Occupational Health and Safety Act (Act 85 of 1993), while for the mining industry they are published in the Mine Health and Safety Regulations2 of the Mine Health and Safety Act (Act 29 of 1996). Hereafter, reference will only be made to the abbreviations, RHCS and MHSR for simplicity. Whilst conducting research on dermal exposure to metals, differences in the assignment of skin and sensitisation notations between the RHCS, the MHSR and other countries became apparent. It raised the question of whether this is also true for other substances and if so, to what extent?
The history of skin notations associated with OELs can be traced back to 1958, when the approach was first introduced by Germany. In 1961, the American Conference of Governmental Industrial Hygienists (ACGIH) adopted the same approach.3 The only original intention of a skin notation was for it to be used as a qualitative warning sign, indicating that a specific substance may penetrate the human skin with the potential of contributing significantly to total systemic toxicity.3,4
At present skin notations are associated with almost every country’s list of OELs, but assignment thereof by countries is inconsistent.3,5 Clearly defined, universal (world-wide) criteria for assignment of skin notations do not exist and in some instances, incorrect assignment of notations to substances causing skin irritation, corrosion and sensitisation has also occurred.3 However, insufficient information on skin absorption rates of substances has also contributed to the inconsistent assignment.3,6 Numerous scientific papers, scientific committees and commissions have proposed strategies for improved, “harmonised” assignment and use of skin notations.3,7-12 Universal criteria for assignment of skin notations would ensure consistent assignment and use thereof globally as qualitative warning signs. In particular, improvement in the assignment and use of skin notations has been recommended by the National Institute for Occupational Safety and Health (NIOSH) skin notation criteria.13
In general, a sensitisation notation refers to the potential of a substance to produce sensitisation.14 Sensitisation occurs through immunologic mechanisms. Initially, upon exposure to a sensitiser, little or no response is observed. However, after sensitisation has occurred, subsequent exposure to the sensitiser, even at minute concentrations (even far below the OEL), may elicit a response also known as a hypersensitivity reaction. These hypersensitivity reactions may have an immediate (e.g. asthma, rhinitis) or delayed onset (e.g. skin rash). Unlike skin notations, there is no published literature comparing sensitisation notations of different countries.
The aims of this study were to quantitatively and qualitatively compare South African skin notations and sensitisation notations with those of other selected developed countries in order to ascertain the assignment criteria and use of these notations relative to those of other developed countries.
 
Methodology
The most recent published lists of OELs with skin and sensitisation notations from South Africa,1,2 the United Kingdom,15 Sweden,16 Australia,17 Finland,18 British Colombia (Canada)19 and the ACGIH (United States of America)14 were used. With the exception of Australia, the other countries or institution were selected as representatives of developed countries in North-America and Europe, all with reputable occupational hygiene standards. Comparisons were made between the use of skin notations and sensitisation notations in these countries, based on the names of substances published in the lists. CAS numbers were used to identify chemicals listed under different (synonymous) names. Isomeric compounds were either grouped by some countries or individually listed by others. Where possible, data were adjusted by grouping isomeric substances, thereby giving the combined group of isomers a skin notation or sensitisation notation. Consequently, there may be differences in the numbers stated here for each country from those published in the national lists. These differences are considered to be small and of minor importance when major differences between countries are discussed.1 In this study the percentage agreement between two countries/institutions was calculated based on the number of substances sharing a notation in relation to the sum of the substances with a shared notation and those only listed by the two countries as depicted by the following formula:
 
 
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Thus, the absence from the list of OELs in one country (i.e. no OEL or skin notation) but presence of an OEL with a skin notation in that of the other country is considered a disagreement. The same is true if both countries list an OEL for a substance, but only one assigns a skin notation. Irrespective of whether a country/institution has evaluated a substance or not, the absence of a substance in one country’s list of OELs is considered as not recognising any hazard or risk associated with inhalation and/or skin exposure as identified by other countries/institutions.      
 
Results
Skin notations
A total number of 115 and 112 substances with skin notations are listed in the RHCS and MHSR respectively. Both lists share 103 substances, with 12 being listed only by the RHCS and nine being only listed by the MHSR (Figure 1A, first bar). The agreement or “overlap” between these two lists is 83.1%. However, when the lists of RHCS (Figure 1A) and MHSR (Figure 1B) are compared to those of other countries, there is far less agreement and it varies between 32.7% and 57.2% for the RHCS (mean of 42.9%) and between 33.3% and 58.2% for the MHSR (mean of 45.8%). In both cases, the smallest agreement is with Sweden and the highest agreement with Australia.
The differences in skin notations between countries are further highlighted when the number of substances with skin notations common to the countries is examined (Figure 2). The total number of substances listed by the RHCS and the six other countries is 292, whilst the total listed by the MHSR and the six other countries is 289. For the comparison of the RHCS with other countries, 50 substances with a skin notation are listed by only one of the seven countries, while 51 substances are listed for the MHSR comparison with other countries. Remarkably, in both comparisons, only 27 substances (9.3%) of all the substances with a skin notation appear in all seven of the countries’ lists.   
Skin notations were also compared with respect to definitions and criteria used to assign them. In the MHSR, a skin notation is only explained by the phrase “danger of cutaneous absorption”.2 The RHCS contains the wording “skin absorption” with further explanation thereof in paragraph 40. This paragraph (adopted from the United Kingdom) states that substances with a skin notation have the ability to penetrate the intact skin upon localised contamination (i.e. splashes on the skin or clothing or in certain cases to high airborne vapour concentrations) and, therefore, become absorbed into the body.1 However, in the United Kingdom specific reference is also made to skin absorption leading to systemic toxicity. The criteria used for assignment of a skin notation in the United Kingdom are based on available data/experience/predictions which suggest a substantial contribution of the skin exposure route to body burden (compared to the airborne exposure at the OEL) and causing systemic effects. This implies that assessment of airborne exposure concentrations alone may be insufficient in describing exposure and the health effects.15 In Sweden reference is only made to substances which can easily be absorbed percutaneously.16 The Finnish notation refers to absorption through the skin causing health effects.18 Skin notations in Australia, British Colombia (Canada) and the ACGIH refer to substances that contribute significantly to the overall exposure by the cutaneous (skin) route.14,17,19 British Colombia and the ACGIH explain exposure as being through direct skin contact (solids, liquids) or vapour and includes contact with the mucous membranes of the eyes.14,19 Additional explanations of direct effects of certain substances (e.g. dermal irritants) on the skin and mucous membranes as well as substances functioning as vehicles or enhancers of penetration (i.e. solvents) are included by Sweden, Australia and the ACGIH.14,16,17 
 
Sensitisation notations
The only difference between the RHCS and MHSR sensitisation lists is that the RHCS lists isocyanates as a group (as –NCO) as well as six individual isocyanate compounds, each with their own sensitisation notation, whereas MHSR have only one notation for isocyanates (as –NCO). Only the RHCS, Sweden and British Colombia listed individual isocyanate compounds with sensitisation notations and it was, therefore, decided to consider isocyanates as a group in this study. It also means that in this study there is no difference between the sensitisation lists of the RHCS and MHSR, with both listing seven substances. A formal sensitisation notation is not listed by Finland, only standard risk phrases relating to the special risks attributed to dangerous substances and preparations. It was, therefore, not included in this data set.
The overlap between the South African lists (RHCS and MHSR) and those of other countries ranges between three and six substances (mean 4.8) with one to four substances only being listed in the South African Regulations (Figure 3). Eleven, 44 and 45 substances listed by the United Kingdom, British Colombia and Sweden, respectively, do not appear in the RHCS or MHSR.
 Figure 4 illustrates that of the 84 substances with a sensitisation notation, 32 (38.1%) are listed by only one country. Surprisingly, only three substances are listed by all six countries, representing 3.6% of all substances listed with a sensitisation notation. These three substances are phthalic anhydride, trimellitic anhydride and the group of isocyanates (-NCO).
According to definitions, the notation of sensitisers by countries can be divided into those only listing respiratory sensitisers causing occupational asthma (i.e. RHCS, United Kingdom) and those listing the substances merely as sensitisers (MHSR, Australia, Sweden, British Colombia and ACGIH). The assigned sensitisation notation in the United Kingdom is accompanied by risk phrases warning against sensitisation through inhalation (R42) and sensitisation through inhalation and skin contact (R42/43). Five substances without a notation, but with a R43 risk phrase (sensitisation through skin contact) are also listed by the United Kingdom.15 Sensitisation notation by the ACGIH refers to the potential for a substance to produce sensitisation, as confirmed by human or animal data. The notation does not distinguish between the routes of exposure nor to the reactions.14 British Colombia documentation states that it covers all ACGIH-identified sensitisers, yet when analysed there are significant differences (British Colombia list a total of 49 and ACGIH 35, with 2 only listed by ACGIH and 16 only by British Colombia). In Sweden and Australia, the skin and respiratory organs are named as positions of hypersensitivity reactions.16,17 Furthermore, apart from providing a list of substances with sensitising properties, Sweden also provides a separate list, containing names of highly sensitising substances, for which permission from authorities must be obtained before being handled.16   
 
Discussion
Skin notations
Nielsen and Grandjean compared skin notations of five European countries with that of the ACGIH. They found that agreement ranged between 24.8% (Slovenia) and 61.6% (Denmark) with a mean of 40.4%.1 Agreement of the RHCS with other countries was slightly higher (42.9%), while that of the MHSR was 45.8%. The low agreement of South African RHCS and MHSR lists with those of Australia, Finland, ACGIH and British Colombia (Canada) is attributed to the number of substances only appearing in the lists of the other countries, ranging between 65 to 109 for RHCS and 65 to 106 for MHSR. One of the main reasons given by Nielsen and Grandjean for the lack of agreement relates to differences in the written criteria used for assigning skin notations.3 From our results it is clear that there are sometimes subtle differences in the interpretation and intention of the criteria used to assign skin notations between countries. According to definitions and explanatory documentation of countries showing large disagreements with South African notations, it is not that skin notations are incorrectly assigned to for instance skin irritants and corrosive substances. However, the ACGIH assigns skin notations to substances with an acute dermal lethal dose (LD50) < 1000 mg/kg. Furthermore, British Colombia and the ACGIH clearly include contact with mucous membranes of the eyes as skin contact. The lack of proper data on skin permeability/penetration for many substances has also been implicated as a reason for lack of agreement.3,6 In addition, reasons for assignment or non-assignment are not always accompanied by specific reference to documentation and arguments.3 This lack of transparency makes it impossible to trace why substances were or were not given a notation but also to establish when last assignments were made. Yearly additions and retractions are only evident for the ACGIH. Unfortunately, neither the RHCS nor the MHSR provide supporting documents explaining assignment or non-assignment for individual substances. Not only in South Africa, but also in other countries, there is thus an urgent need to develop and implement a strategy which will ensure frequent revision of assignment of skin notations accompanied by accessible supporting documentation.
NIOSH published a new strategy for assigning skin notations in 2009.13 Based on scientific evidence the existing 142 substances currently listed by NIOSH and other substances will be assigned with multiple (or combined) skin notations distinguishing between effects caused by exposure (Table 1). Substances for which insufficient data associated with skin exposure exist will also be identified. A notation (SK) for a substance not posing a skin health risk (based on current knowledge) will also be assigned.
The skin is also often exposed to mixtures of ­substances and assessing it will prove as complex as dealing with airborne exposures to mixtures of gases or vapours.3,11 The NIOSH skin notation criteria do not incorporate a notation for substances known to enhance the skin permeation of other substances. However, such a notation may easily be incorporated in future.
 
Sensitisation notations
As already noted, there is no published literature comparing sensitisation notations of different countries. The lack of disagreement for sensitisation notations between countries is quite astounding. This is further accentuated when sensitisers listed by other countries in this study (excluding RHCS and MHSR) are compared. The list of sensitisers listed by all five countries only increased to five substances (6% of all substances listed), adding gluteraldehyde and maleic acid to the existing three substances. If the United Kingdom is also excluded, the list increased to ten substances (12.3% of all substances) for the four countries (adding formaldehyde, methyl acrylate, n-butyl glycidyl ether, phenyl glycidyl ether and turpenes). The lack of human evidence is even more pronounced in skin sensitisation and allergic contact dermatitis11 which may explain the necessity to rely heavily on predictions and animal data, which in turn lead to varied often subjective interpretation and assignment of notations. The lack of accompanying documentation and, therefore, transparency may also contribute toward this situation.
Alarmingly, the RHCS only acknowledges sensitisation through inhalation. Although not implied by the definition, the same is also true for the MHSR because of the identical lists of sensitisers.
 
Conclusions and recommendations
Skin notations in the RHCS and MHSR only had a mean agreement of between 42.9% and 45.8% with those of other countries, while only 3.6% agreement existed for sensitisation notations. It is also clear that there are sometimes subtle differences in the interpretation and intention of the criteria used to assign skin notations between countries. As with many other countries there is a lack of frequent review and updates of these notations, therefore, there is an urgent need to develop and implement a strategy which will ensure frequent revision of assignment of skin notations accompanied by accessible supporting documentation. Adoption of the NIOSH skin criteria for use in South Africa is recommended. It is recommended that all sensitisers, irrespective of the route of exposure, should be acknowledged and incorporated in the RHCS and MHSR and other legislation. The development of multiple sensitisation notation criteria whereby the route of exposure, i.e. respiratory (SEN:RES) and skin (SEN:SK) or a combination thereof (SEN:RES/SK) for inclusion in the RHCS and MHSR is also recommended. This will enable occupational hygienists to distinguish more efficiently between different skin and sensitisation hazards, thereby enabling them to assess and control exposure more appropriately.
 
 
LESSONS LEARNED
1. Clearly defined, universal criteria for assignment of skin notations do not exist.
2. The absence of a skin notation for a substance does not necessarily imply the absence of a skin hazard.
3. Sensitiser notations in the RHCS and MHSR only refer to respiratory ­sensitisers and not to skin sensitisers.
4. The assignment and use of a skin or sensitiser notation in one set of ­regulations or country is not necessarily the same as for another set of regulations or country.
 
References
1. Department of Labour, South Africa. Regulations for Hazardous Chemical Substances (GN R1179, 25 Aug 1995 as amended by GN R930, 25 Jun 2003 and GN R683, 27 Jun 2008). Pretoria: Government Printer.
2. Department of Minerals and Energy. South Africa. Mine Health and Safety Regulations (GN R904, 2 Jul 2002 as last amended by GN R94, 1 Feb 2008). Accessed on 10 Feb 2010. Pretoria: Government Printer.
3. Nielsen JB, Grandjean P. Criteria for skin notations in different countries. Am J Ind Med. 2004;45:275-280.
4. Sartorelli P. Dermal exposure assessment in occupational medicine. Occup Med. 2002;52:151-156.
5. Fiserova-Bergerova V, Pierce J, Droz P. Dermal absorption potential of industrial chemicals: criteria for skin notation. Am J Ind Med. 1990;17:617-635.
6. Semple S. Dermal exposure to chemicals in the workplace: just how important is skin absorption. Occup Environ Med. 2004;61:376-382.
7. De Cock J, Heederik D, Kromhout H, Boleij JSM. Strategy for assigning a ‘skin notation’: a comment. Ann Occup Hyg. 1996;40:611-614.
8. Czerczak S, Kupczewska M. Assignment of skin notation for maximum allowable concentration (MAC) list in Poland. Appl Occup Environ Hyg. 2002;17:187-199.
9. Chen C-P, Boeniger M, Ahlers H. Use of dermal LD50 as criterion for skin notation. Appl Occup Environ Hyg. 2003;18:154-155.
10. Kupczewska-Dobecka M, Czerczak S. The skin notation in the MAK list and classification of dangerous chemicals. Int J Occup Med Environ Health. 2006;19:84-91.
11. Sartorelli P, Ahlers HW, Alanko K, Chen C-P, Cherrie JW, Drexler H, et al. How to improve skin notation. Position paper from a workshop. Regul Toxicol Pharmacol. 2007;49:301-307.
12. Lavoué J, Milon A, Droz PO. Comparison of indices proposed as criteria for assigning skin notation. Ann Occup Hyg. 2008;52:747-756.
13. Schulte P, Ahlers HW, Chen C-P, Demchuk E, Dotson GS. Current Intelligence Bulletin 61. A strategy for assigning new skin notations. Cincinnati (OH): National Institute for Occupational Safety and Health (US); 2009 July. 59 p. Report No. 2009-147.
14. American Conference of Governmental Industrial Hygienists (ACGIH). Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices. Cincinnati (OH): ACGIH; 2009. 254 p.
15. Health and Safety Executive. EH40/2005 Workplace exposure limits. United Kingdom: HSE books. ISBN: 0 7176 2977 5.
16. Swedish Work Environment Authority. Occupational exposure limit values and measures against air contaminants. In: Statute Book of the Swedish National Board of Occupational Safety and Health. Ordinance (AFS 2005:17). Sweden: SWEA.
17. National Occupational Health and Safety Commission. Adopted national exposure standards for atmospheric contaminants in the occupational environment [NOHSC:10003(1995)]. Canberra: Australian Government Publishing Service.
18. Sosiaali-ja Terveysministeriö, Tyosuojelusäädöksiä. Finland. HTP-Arvot 2009. Haitallisiksi tunnetut pitoisuudet. Accessed on 12 Feb 2010. Available at http://www.ketsu.net/htp/HTP2009.pdf.
19. British Colombia, Canada. Workers Compensation Act. Occupational health and safety regulation (B.C. Reg. 296/97 as last amended by B.C. Reg. 258/2008). Available at http://www2.worksafe.bc.com/ Publications/OHSRegulation/GuidelinePart5.asp#ExposureLimits.
 
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