[ Table of contents ]   [ List of papers ] Chemical risk assessment and occupational hygiene preventive measures in small and medium-sized enterprises (SMEs) Chapter 3 Occupational and Chemical Safety and Health in SMEs

 

SUMMARY OF INDUSTRIAL PROCESSES AT SMES

The survey covered 320 SMEs which employed a total of 11,459 workers in the five countries under study. Despite the differences in their geographic locations, the work practices in the same type of SMEs in different countries and the associated chemical hazards were similar. In order to appreciate the hazards involved, the risk assessment and the preventive measures, a brief description of a representative sample of these SMEs is necessary. This will include a description of the processes, the chemicals used and the associated work practices. Although the processes are well documented in the literature , their description is only intended to ensure the coverage of any practices which are peculiar to local situations.

Furniture upholstery

Old furniture is stripped down to the wooden skeleton. It is re-padded with sponges which are fixed to the wood frame using neoprene adhesive or a power gun. After the adhesive dries, the chosen textile is stitched onto the sponge layer using tailor made tools e.g. long pins. The main chemical used in this industry is neoprene adhesive, a synthetic adhesive that releases formaldehyde vapour into the working environment thus exposing the workers through inhalation. In a typical SME, about 10 kg of material are used per month. The empty containers that have residual adhesive in them, are disposed of in the municipal solid waste bins. One enterprise used a chemical named "OGhiriO", which is a wood glue. The constituents of this chemical are not known. The health effects resulting from its use are not documented. It is a widely used chemical even at the household level. It is less likely that it has any serious acute health effect.

Furniture carpentry

This is basically a traditional woodworking shop. Wooden panels are cut using the classical woodworking machines such as band saw, circular saw and lathe. Three chemicals namely, contact cement, polyvil and gasoline are used in the process of producing the finished furniture. No surface finishing or making up was done in the enterprises visited. Contact cement, also known as colicol, was used to glue wood. In the majority of SMEs, a small amount was consumed (10 kg/month) during production. As it contains solvents, exposure through inhalation and skin was likely. Polivil was used for gluing formica sheets on wooden structures. Fifty kg of this viscous liquid adhesive were stored on the shop floor. Polivil contains the solvent based glues. Cloths wetted with Gasoline were used for cleaning excess adhesive from the wooden surfaces. The chemicals used in other enterprises were the same except that lacquers and varnishes were also used by the workers in the spraying area.

The surface finishing chemicals, particularly the lacquers, could contain toxic material such as isocyanates and ethylene diamine catalyst for epoxy resins which are skin hazards. The finishing was done at two stages. First, a specific mixture of base lacquer and catalyst (ingredients: Citopac Poliuretanico (FABB 6100268) + Catalizzatore Poliuretanico (FABB 6100292) was prepared and sprayed (Picture 4.5). When the first layer dried, another finishing lacquer-catalyst mixture (ingredients: Citopac Poliurentanico (FABB 701000 3A) + Catalizzatore Poliuretanico (FABB 701000 3D)) was sprayed on top. Exposure to these chemicals mist was excessive and could have serious health implications. No respiratory protection was used by the workers. Ventilation and isolation were insufficient to control the exposure through inhalation and skin contact.

Ink production

An enterprise produced 5-6 tonnes/month of water or solvent based inks for the local market consumption. Producing a batch of solvent based ink with certain specification entails mechanical mixing of 10-15% ink pigment powder, 60% mono- or mixture organic solvent, 22% resin (18% of which is resin solvent), and 5% antifoaming agents. The ink pigments used include aluminium powder. About 30 kg. of the powder are emptied from paper bags into a container to be mixed with - 100 litres of solvent (e.g. isopropanol) dispensed from local storage on shop floor. Resin (e.g. nitrocellulose, resin solvent (e.g. dibutylphthalate) and antifoaming agents (e.g. monoethylamine) are also added to the mixture in the appropriate proportions in a similar fashion. The mixture would be finally processed on a filtering machine that will ensure the absence of ink lumps in the final product. During this process, workers were exposed through the respiratory and dermal routes to appreciable levels of powder and solvent vapour. No effective exposure preventive measures were observed during the study, thus rating the industry as a high risk area.

Plastic bags

In these enterprises, high density polyethylene, low density polyethylene and linear low density polyethylene were used as raw materials. The material is sucked from a barrel by a vacuum system and transferred to a melting chamber. The molten raw materials are blown out of the extruder as a thin film, which ran between a series of cylinders to form a big roll. The roll is then transferred to a printing machine using different coloured inks diluted with a solvent (e.g. isopropanol or methyl acetate). Five hundred kgs. of inks are normally sorted on the shop floor. Solvents are dispensed from a barrel also found in the same area. Both inks and solvents get mixed manually and fed to the printing machine. Exposure to ink mist and solvent vapour through skin and respiratory system is likely. The printing machines allowed automation of diluted ink feeding; however, this is not practiced. Workers at the SME visited did use gloves while handling solvents, but the gloves were not maintained properly and were found to be contaminated from the inside, thus increasing the possibility of dermal exposure. The empty ink containers were dumped in the municipal bins while still containing residues of the inks. Any polyethylene rejects and bags were minced in a shredder and re-used in the process in small percentages with new raw material.

Aluminium frames

In these enterprises, aluminium frames for fences, windows and other building materials were assembled. Large bars of aluminium are cut using special guillotines and perforated using a drill, and eventually bolted together as needed. The only chemical compound used in this enterprise was an acrylic sealant (trade name: ÒDutchmanOsO). Small quantities were

used when there was a need for water proofing gaps in the structure. About 4 tubes were in stock (0.5 kg each). Very little exposure was suspected.

Metal works (Iron tanks and mixers)

These enterprises fabricated metal structures such as tanks and mixers from solid stocks using traditional machinery and processes such as lathe, drill press and burning and welding processes. Mild steel was used to fabricate the structures. Methane gas was used to heat the metal and then oxygen gas passed onto the hot metal giving rise to an oxidative exothermic reaction which melted the metal without an additional source of heat. The process is hazardous, exposing the workers to large amounts of fumes especially when the base metal contained toxic metals such as chromium. Manual metal arc welding was used to assemble the different parts. In the paint section, red iron oxide, paints and lacquers were applied by brushes and conventional air spraying techniques. Paints were then sprayed and left to dry. Lacquer was then sprayed to give the metal structure a glossy finish and protect the paint layer. Workers were constantly exposed through inhalation and skin absorption to solvent vapours and paint and lacquer mist. Workers infrequently used dust masks which were badly maintained and could afford little protection against solvent vapours. Diesel was used as a source of fuel for electrical generators. Exposure to diesel fumes was an additional potential hazard especially when the generators were installed on the same shop floor level.

Foundry and electroplating

The process included the sieving of foundry sand which is then dried using a propane fed flame. The second step is assembling the mould using the pattern. In this step, calcium carbonate was sprinkled on the pattern to prevent sand from sticking on the surface during the preparation of the mould. When moulds are ready, the melting required is done using diesel as fuel. Molten metal is poured into the moulds. Finally, the moulds are opened and adherent sand and superfluous metal edges from the finished casting are removed. Silica dust from foundry sand, calcium carbonate dust, carbon dioxide and carbon monoxides gas due to incomplete combustion, and toxic metal fumes resulting from pouring the molten metal into the moulds are the main chemicals presenting a potential for exposure through inhalation. The waste, including the foundry sand (1.5 tonnes), is disposed of at open dump sites after exhaustive use. Small amounts of non-recyclable zinc is disposed of in municipal bins.

A section in this factory is designated for electroplating. Finished castings are cleaned by electrolytic degreasing with an aqueous alkaline solution containing mainly caustic soda, trisoduium sulphate and sodium cyanide at a concentration of ^20g/l. The chemicals are stored unlabelled and in a disorganized fashion on the shop floor. Casts are washed in water, a 10% sulphuric acid solution to neutralize the concentrated alkali degreasing solution, and finally dipped in water before entering the 700 litre nickel electroplating bath containing 1% sulphuric acid solution. Silver nitrate is used for silver plating. A developer, Ozasol EN 143, was used to improve the development of the electroplated metal film on the cast. The final stages include mechanical grinding and polishing of the articles and their manual cleaning using gasoline, before they are sprayed for protection using as glossy finish a lacquer labelled ÕDucoluxO which is thinned by a thinner known as ÕPower.

In the electroplating section of the industry, workers are potentially exposed to concentrated acids and alkali. They are also exposed to acid mist, cyanide mist and alkaline mist from electroplating baths. Exposure to the dust from the different chemicals could also occur during manual handling of the articles during weighing and transfer to baths. Workers on the grinding machines are potentially exposed to fine metal dust liberated from the metal pieces. Waste chemicals are normally disposed off by drainage in the public sewers.

Cotton rolls

In this enterprise, imported cotton or polycotton are woven into rolls on the weaving machines. No other chemicals or raw material are used in the process. Workers are exposed to cotton and polycotton dust from the process. Approximately 1% of raw material is lost as waste.

Shoe making

The main raw materials used by the two enterprises covered in the study were leather and rubber. Leather is manually cut out to desired shape and size using razors. The different upper leather parts of the footwear are then assembled together by stitching and/or glueing together using a liquid rubber adhesive. Hexane is used for general leather cleaning. Excess adhesives from footwear upper leather and soles are removed by white spirit or gasoline, which are also used by workers for cleaning their hands. At the last stages of production, plastic parts are tenderized by being dipped manually in toluene and inserted at the back end of the footwear. The bottom face of upper footwear are then ground for smoothing and sticking of the soles. In the final stages before packaging, some quick acting, self-polishing finishing compounds for heels and edges made of leather (called Finicolor) are applied for masking any production defects.

Exposure to solvents is the main occupational hazard in this industry. All operations are carried out manually. Workers are exposed through the respiratory route while handling solvents at the benchtop and particularly during the dipping of plastic inserts in toluene. Workers on the grinding machines are exposed to leather and rubber dust containing adhesive residues and other colouring material. The main waste produced during the production are leather cutoffs and empty containers containing residues of adhesives and unevaporated solvent. All waste is disposed of in municipal bins. The processes in other enterprises are virtually identical except that finishing compounds (such as Kentac, Duplex, Diamante, Finicolor) are used.

Gold electroplating

This industry used a number of chemicals for gold plating. Metal pieces are manually assembled, then transferred to a 300 litre degreasing tank containing trisodium phosphate, caustic soda and sodium cyanide (20g/l). Metal pieces are washed in water and neutralized in 10% sulphuric acid and transferred to a 700 litres nickel electroplating bath which contains a brightener (Makrolux NF) and a brightness correcting solution (Ni Konz./Conc.). The pieces are washed with water before their transfer to the electroplating bath containing gold, 10% hydrochloric acid and potassium cyanide. Gold chips are dissolved in a boiling 10% nitric acid solution before transfer to the bath. The process is carried out near a fan. Gold plated articles are then ground, manually washed in gasoline and dried in fine wood dust.

The potential for exposure to chemicals exists in all stages of the process. First the workers are likely to be exposed to alkali and cyanide mist from the degreasing bath. However, the intensity of exposure is reduced by the use of a foaming agent ÒSprYhexO. Personal protective equipment is also used for this purpose, but is not well maintained. Exposure to nickel salts from the electroplating bath could occur. Manual handling of concentrated acids and alkalis exposed the workers to acid fumes and caustic soda dust. The grinding processes exposed the workers to dust containing metals and oxides.

Hot-dip galvanizing

One enterprise produced 50 tonnes of galvanized metal articles every week. The chemicals used included hydrochloric acid (30-40%), ammonium chloride, zinc, zinc chloride, lead, sodium hydroxide, and diesel oil which was used as fuel for heating zinc baths. The process is similar to electroplating in that workers are exposed to acid and metal fumes. The solid waste is removed through scavenging every fortnight. Dilute hydrochloric acid is carted away to a disposal site after neutralization.

Car body filler manufacturing

These enterprises use a number of chemicals including zinc phosphate, isobutyl acetate, xylene, toluene, propyl alcohol, butyl alcohol, calcite, talc, barytes, nitrocellulose chips and bentone. The chemicals are sieved, mixed and poured with the potential of exposure all through the shop floor. Whilst the storage of toxic and explosive chemicals is not adequate, the process does not product waste in significant quantities.

Textile dyeing

The enterprises use a variety of numerous chemicals including acids, alkalis, bleaching agents, flammable and explosive solvents, dyes and pigments. The process involves manual mixing of chemicals and numerous exposure patterns. Liquid waste from dyeing machines and a sedimentation tank are usually discharged into the municipal sewers. Some of the open drains within the enterprise could with time clog and lead to spillage within the vicinity.

HYGIENE PRACTICES AT SMEs

Handling of chemicals

In close to 70% of the enterprises, chemical containers were not properly labelled. Very few labels were in local languages, which does not bode well in countries with high illiteracy rates. The majority of the SMEs stored enough chemicals for a week's use on the premises. Only the larger enterprises stored chemicals in hundreds and thousands of tonnes on premises. Others, such as pesticide formulators, stored large quantities during peak seasons only.

In some cities, such as Lahore in Pakistan, chemicals are sold in wholesale markets such as those selling grocery items and cereals. The chemicals sold in such markets included toxic and flammable materials, which given their large quantities, posed grave dangers to residents and the public and the immediate environment. The situation would become particularly more serious when the goods are displayed outside the shops in an attempt to attract customers, causing encroachments of the road, a condition which, under hot climatic conditions, aggravates their dangers.

Based on the work patterns described previously, the routes of entry of the chemicals to the body are traditionally those of inhalation, skin absorption and ingestion. The latter was particularly common in view of the scarcity of washing facilities and the poor hygiene conditions under which eating and drinking took place.

Fire and explosion

The majority of the SMEs were judged to possess low fire and explosion potential. The very few which caught fire in the past included a laundry where the fire was due to a short circuit in a machine in the vicinity of an open gasoline container. Another incident happened in a furniture workshop where fire was started by a burning cigarette stub, setting off flames from rags soaked with methylated spirits. In a car repair shop an explosion occurred due to a leaking acetylene gas cylinder.

Operational control measures

In general, there is a marked absence of engineering and other occupational hygiene control measures in SMEs. Ventilation systems are uncommon, and the concept of substitution is unpopular. While in some enterprises workers use improvised personal protective equipment such as old car tyre tubes which are worn as boots to provide skin protection, proper personal protection is non-existent. Similarly, the use of barrier creams and lotions for the protection against the deleterious effects of solvents is unheard of. Fire fighting emergency and first aid facilities are also inadequate. With the exception of a few enterprises, air monitoring is unknown. Few medium-sized enterprises had access to biological monitoring and social security systems, a privilege which the majority did not enjoy.

Waste disposal and environment

Most of the industrial chemicals used by SMEs are packaged in plastic containers which are corrosion proof and non-destructible. Such qualities encourage people to use the empty containers for other purposes including the storage of water and foodstuffs. This in turn allows chemical residues to contaminate water and food with subsequent short and long-term health effects.

Except for two chemical manufacturing enterprises, both of which belonged to multinationals, none had treatment facilities for chemical waste. Chemical liquids, solids, gases and fumes were released to the environment damaging not only cultivable land but polluting water sources and damaging the health of plants and other livings. The effect on the health of the public could not be easily assessed. Where waste products were usable, such as soap sludge from soap factories, it was collected by the general public for domestic uses. Similarly, wood shavings and dust were used as cooking fuel. Wood powder was also used to preserve ice blocks. Meat debris which were removed from animal hides during dehairing in tanneries were sold for glue making enterprises. However, the discharge of untreated chemical wastes from tanneries into the environment defies the imagination of mankind.

Work organization

Small and medium-sized enterprises differed markedly in the organization of work. Whilst the latter group showed some resemblance to work organization and general housekeeping, small enterprise practices in this regard were relaxed. Work areas were littered with half-filled and empty chemical containers, machine tools and waste. This could be attributed partially to lack of space and the lower level of workers' literacy.

Welfare facilities

While all the medium-sized enterprises covered in one country had their own washing and toilet facilities, a large number of small-sized enterprises (68%) had no washing/toilet facilities. Workers in these enterprises went to nearby public toilets or water washing facilities. The basic sanitation facilities were not much different in the industry than in the community in general. In fact, such facilities are better in the medium sized enterprises than those available to the general public and in most households. The lack of adequate washing/toilet facilities combined with the inadequate eating facilities resulted in the accentuation of the chemical hazards and in many cases biological hazards to which the workers are already exposed. A large number of workers were exposed to chemicals unnecessarily due to poor hygiene eating habits. In a large number of small and a significant number of medium-sized enterprises, the meals were carried by the workers from home and eaten on the premises, sometimes during work. In many cases workers sat on the floor, opened their meal boxes (or cloth rags in which meals had been wrapped) and ate with unwashed hands. In many such cases, chemicals with potential long term health implications were not properly washed off before eating. Smoking and drinking tea and coffee during the work are customary practices among workers especially in the small-sized enterprises. One third of the medium-sized enterprises had their own canteens, which none of the small-sized enterprises enjoyed. It was estimated that workers in 34% of the medium-sized and 84% of the small-sized enterprises brought their meals from home or from a nearby restaurant.

In another country, 27% of the medium-sized enterprises surveyed provided subsidized food for their workers, while the rest provided canteen facilities only. Eating facilities were also available in 15% of the small-sized enterprises. In the remaining enterprises, the workers carried food from home or bought it somewhere else. In general, toilet and washing facilities were available but some were not up to standard.

AGE DISTRIBUTION AND THE GENDER OF WORKERS AND WORKING HOURS

An overwhelming majority of the workers in both the small-sized and medium-sized enterprises were young and fell in the age group of 19-35 years (55.9% in the small-sized and 55.6% in the medium-sized enterprises). The incidence of child labour in the surveyed enterprises was almost negligible; 1.4% of the total workforce were children below the age of 14. Small-sized enterprises had 5.9% and medium-sized enterprises had 1.2% child workers. The reason for the low child labour rate could be attributed to the level of skill and physical strength required by some enterprises. Table 3.1 shows the percentage of age distribution in a representative sample of 61 SMEs.

Table 3.1 Age distribution of the workers in SMEs

As far as the gender profile of the workforce in the SMEs covered by this study is concerned, there was a marked difference between countries. Whilst women workers were employed by 4% of the SMEs surveyed in Pakistan, they constituted 54% of the workforce in the 241 SMEs surveyed in Bangladesh.

Almost all small enterprises worked single day shifts extending from 8 to 19 hours. The medium-sized enterprises had varying shifts which tended to be longer than those in small enterprises. Lunch breaks of one hour each were observed by almost all SMEs, and rest breaks were staggered in a manner that did not affect production lines.

HEALTH COMPLAINTS IN SMEs

The study surveyed workers' opinions concerning the effect of exposure to chemicals on their health. Whilst one third of SMEs did not mention any specific problems, the rest complained about a number of ailments such as headaches, respiratory and skin problems. Addition to solvents was also pointed out in some enterprises. A summary of these complaints according to industry appear in Table 3.2.

Table 3.2 Health complaints as reported by workers in SMEs

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