CHAPTER THREE – A BRIEF HISTORY OF AWARENESS OF THE RISKS OF EXPOSURE TO RESPIRABLE CRYSTALLINE SILICA
Silicosis is not a modern disease; in 400 BC, Hippocrates, the founder of medicine, noted “breathlessness” in miners. The Industrial Revolution in the UK led to the rapid development of what are known today as “occupational” or “industrial diseases”. In 1843 Dr Charles Favell wrote about the well-known phenomenon of “grinders asthma” in the metal grinders of Sheffield; this would later be determined to be silicosis. The condition was named in 1870 by the Italian Achille Visconti from the Latin word silex or flint.
By the turn of the 20th Century, there was increasing evidence that many lung diseases were occupational in origin. As a result, unions pressed for occupational diseases to be included in workers’ compensation schemes. In 1906 a Departmental Committee on Compensation for Industrial Diseases was appointed by the UK Parliament to consider which diseases should be added to the Third Schedule of the Workmen’s Compensation Scheme1.
In 1915 Dr Edgar Collis, HM Medical Inspector of Factories, delivered the Milroy Lectures at the Royal College of Physicians, entitled: Industrial Pneumonoconiosis, with Special Reference to Dust-Phthisis2, which drew attention to the role RCS played in causing silicosis.
As a result of the growing awareness of risks and campaigning by unions, in 1918, The Workmen’s Compensation (Silicosis) Act 1918 was enacted in Great Britain. This Act gave the Secretary of State the power to make schemes for the payment of compensation to workers in specified industries or processes who were exposed to silica dust and suffered illness or death as a result. Over the next 20 years, various Schemes and variations were made to the Workers Compensation Act in respect of compensation for silicosis.
These Schemes were the forerunner to the National Insurance (Industrial Diseases) Act 1946, which was the forerunner to Industrial Injuries Disablement Benefit. Pneumoconiosis (including silicosis) remains a prescribed disease for the purposes of this benefit.
Unlike asbestos, specific regulations regarding RCS have not been enacted in the UK. In 1997 the International Research Agency for Cancer classified silica as a Group 1 carcinogen3; however, it was not until 2002 that a WEL for silica was introduced by the enactment of the Control of Substances Hazardous to Health Regulations 2002. This allowed a Maximum Exposure Limit (“MEL”) for silica of 0.3 mg/m3, expressed as an 8-hour time-weighted average (“TWA”). The Regulations provided no short-term workplace exposure limit (“STEL”). (STEL is a maximum level of exposure allowed over a period of 15 minutes).
In 2006 the WEL was reduced to a maximum MEL of 0.1 mg/m3, expressed as an 8-hour TWA; this level remains the same to date. In the USA the level is 0.025 mg/m3 and in Australia is 0.05 mg/m3.
In April 2020 the APPG for Respiratory Health, in conjunction with the not-for-profit organisation B&CE, following an extensive inquiry, published the report Silica – the next asbestos?4. The report made various recommendations including that silicosis was included as a reportable condition under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (2013) (“RIDDOR”) for those who are still at work, and to amend the Health Protection (Notification) Regulations 2010 to make silicosis notifiable through Public Health England, thereby creating a national silicosis register. They also recommended the Government introduced new legislation to bring the control of RCS into line with asbestos and the WEL was reduced to 0.05 mg/m35.
In January 2023 the APPG for Respiratory Health, after conducting further inquiries, produced a further report: Improving Silicosis Outcomes in the UK6. Following the first report, the APPG were contacted by several industry experts who suggested there was an incomplete consideration of the risk reduction strategies within the initial report. The recommendations in the 2nd report appear to be more watered down; for example, where initially it was recommended the WEL was reduced to 0.05 mg/m3, the later report recommended the HSE assess and determine if data and technology allow a reduction to this level. The recommendations continued to include increasing awareness for individuals who may have been exposed. It also continued to recommend silicosis was included as a notifiable disease in the Health Protection (Notification) Regulations 20107.
At the date of publication, there have been no changes in legislation to enact the APPG’s recommendations; however, the HSE continues to promote increased awareness of the risks of RCS and provide prescriptive guidance for those in control of, and those working in, industries which use silica8. Detailed guidance has also been produced on health surveillance for those exposed to RCS9 including respiratory questionnaires, lung function tests and consideration for baseline x-rays.
1The Development of Compensation for Occupational Diseases of the Lungs In Great Britain, Andrew Meiklejohn, British Journal of Industrial Medicine, 1954, 11, 198.
2Public Health, October 1915, 11 – 20