Module 4: Organic Dusts - Health Effects Of Cotton And Other Textile Dusts

HEALTH EFFECTS OF COTTON AND OTHER TEXTILE DUSTS:

Definition:

Byssinosis is a generic term that is used to describe acute and chronic airway disease among workers occupationally exposed to vegetable dust arising from the processing of cotton, flax, hemp, sisal and possibly other textile fibres.

Populations at risk:

Occupationally exposure groups include primarily the agriculture and textile industry.

Epidemiology:

The prevalence of byssinosis is higher in workers with:

• longer duration of exposure;
• greater respirable dust exposure (e.g. opening bales and carding)

Interaction between smoking and dust exposure is associated with an increased risk of byssinosis and chronic lung disease.

Causative agent/s and pathological mechanism:

The mechanism is thought to be due to endotoxins (lipopolysaccharide found in the cell walls of gram-negative bacteria) that can induce a number of inflammatory responses causing large and small airways disease and possibly emphysema.

Clinical presentation:

1. The characteristic symptoms are chest tightness, cough and dyspnoea 1-2 hours after the worker returns to work after being several days off.
2. Febrile syndromes (e.g. mill fever) characterised by fever, cough, and other constitutional symptoms such as headache and and malaise are also associated with this condition.



3. The symptoms usually resolve overnight and on subsequent days become milder until by the end of the work week the worker may become asymptomatic (see above figure).
4. Lung function changes commonly associated with byssinosis:
   • Acute effects: characterised by measures demonstrating bronchoconstriction (FEV₁) over a working shift of exposure to cotton dust (especially after an absence offrom exposure to work for 2 or more days).
   • Chronic effects: airway obstruction manifested by reductions in FEV₁ and FEV₁/FVC with increased dust concentration and exposure.

5. The clinical and functional grading of health outcomes associated with cotton and other textile dusts (WHO, 1983) is shown in the table below:

   Classification	Symptoms
   Grade 0	No symptoms
   Byssinosis
   Grade B1 Grade B2	Chest tightness and/or shortness of breath on most of first days back at work Chest tightness and/or shortness of breath on the first and other days of the working week
   Respiratory tract irritation (RTI)
   Grade RTI1 Grade RTI2 Grade RTI3	Cough associated with dust exposure Persistent phlegm (that is, on most days during 3 months of the year) initiated or exacerbated by dust exposure Persistent phlegm initiated or made worse by dust exposure either with exacerbations of chest illness or persisting for 2 years of more
   Lung function
   1. Acute changes:
   No effect	A consistenta decline in FEV1 of less than 5 per cent or an increase in FEV1 during the working shift
   Mild effect	A consistenta decline of between 5 and 10 per cent in FEV1 during the working shift
   Moderate effect	A consistenta decline of between 10 and 20 per cent in FEV1 during the working shift
   Severe effect	A decline of 20 per cent or more in FEV1 during the working shift
   2. Chronic changes:
   No effect	FEV1b: per cent of predicted values c
   Mild-moderate effect	FEV1b: 60-79 per cent of predicted values c
   Severe effect	FEV1b less than 60 per cent of predicted values c
   a A decline occurring in at least three consecutive tests made after an absence from dust exposure of 2 days or more b Predicted values should be based on data obtained from local populations or similar ethnic and social class groups c By a pre-shift test after an absence from dust exposure of 2 days or more

Treatment:

Treatment with bronchodilators and inhaled steroids may improve the physiological responses in lung function but not necessarily the symptoms.

Prevention:

• dust control (exhaust ventilation, cotton washing).
• industrial hygiene surveillance (compliance within the occupational exposure limits).
• worker education and smoking cessation programmes.
• medical surveillance and possible placement of smokers in low dust areas.

Occupational exposure standards:

• Covered by the Hazardous Chemical Substances Regulations (Annexure 4)
• OEL-RL for cotton dust is 0.5 mg/m³ total dust (8-hour TWA) - this is for an area sample using static samplers (focussing especially on intensive operations such as bale opening, waste handling, maintenance of dust extraction equipment and cleaning procedures).
• Applies to dust from processing and handling of raw and waste cotton, including blends except for:
  • dust from weaving, knitting, braiding and subsequent processes;
  • dust from bleached or dyed cotton.
• Where OEL-RL does not apply exposures should be kept below both 10 mg/m³ total inhalable dust (8-hour TWA) and 5 mg/m³ respirable dust (8-hour TWA) using personal sampling.

Compensation for Byssinosis:

This is covered by Circular Instruction 175. The following key criteria are used to evaluate COIDA claims by the Compensation Commissioner’s office:

• occupational exposure to cotton, flax, hemp, sisal for at least 5 years; AND
• clinical features AND work-related symptoms; OR
• > 15% decline in FEV₁ across the first shift of the working week.

REFERENCES:

1. Merchant JA, Bernstein IL, Pickering A. Cotton and other textile dusts. In Asthma in the Workplace. Eds Bernstein IL, Chan-Yeung M, Malo JL and Bernstein DI. Marcel Decker Inc., 2nd edition: 31:595-616, 1999.
2. Balmes JR. Occupational Lung Diseases. In Current Occupational and Environmental Medicine, LaDou J (editor). Lange Medical Books/McGraw-Hill, 3rd edition, New York, 20:320-344, 2004.
3. Government Gazette. Circular instruction regarding compensation for byssinosis under COIDA. Circular Instruction No.175. (http://www.labour.gov.za/docs/legislation/ohsa/index.html)