Under the Control of Substances Hazardous to Health (CoSHH) Regulations Reg.10, you are required to monitor exposure at the workplace. This is required where the CoSHH assessment indiates that, "it is requisite for ensuring the maintenance of adequate control of the exposure of employees to substances hazardous to health."

The intention of this webpage is to diseminate information gathered by Strategic Safety Systems from different printers to enable you to assess whether further monitoring is necessary. Note that this data presently covers only workplace atmosphere measurement from litho printers. Both flexographic and gravure printing involves inks with a high level of solvent and it would always be worth carrying out individual atomsphere measurements in such cases. This service is available from Strategic Safety Systems.

Summary

In general, the workplace atmosphere measurements have shown that both alcohol levels from IPA (isopropanol) and petrochemical solvents in blanket and rollers washes are below both the short term and long term workplace exposure limits (WELs) set either in EH40 Workplace Exposure Limits from the HSE or set by individual chemical manufacturers.

These give some indications of solvent concentrations.  I measured these using Draeger direct-indicating tubes and so the accuracy is limited and the values are for indicative purposes only.

Workplace atmosphere meaurement 1: Blanket washing on a Ryobi 2-colour litho printing press

I measured the following on a Ryobi B3 2-colour press:

Condition Measurement (ppm)
Ventilation by nearby open windows.
Measured as the operator applied blanket wash
25
No ventilation
Measured as the operator applied blanket wash
100
No ventilation
Measured 1 minute after the operator applied blanket wash
10

Considering the worst case condition of 100ppm (which exist for less than 1 minute) and using the concentrations in the blanket wash, (Spectrum 4020 non-water miscible wash) we get the following:

Constituent Max. % OES (ppm) 15 mins Net ppm Ratio

Trimethylbenzene

25

75

25

0.33

Xylene

9

150

9

0.06

Normal and iso-propylbenzene

5

75

5

0.07

Mesitylene

6

75

6

0.08

The indications are that the concentrations are below the OES particularly when the low exposure duration on a small, two-colour press is taken into account.  When averaged over 15 minutes, the majority of which the operator spends on other duties, the exposure is very low.

Workplace atmosphere measurement 2: 2 Heidelberg 5 colour sheet-fed litho printing presses

The results were as follows:


Operation

Test type

Reading
ppm

WEL2
ppm

Blanket wash

Hydrocarbon

<10

450

Roller wash

Hydrocarbon

25

400

Normal running

Alcohol

<100

400

Substances in use:

Substances where there is a known health effect have a workplace exposure limit which is listed in the HSE publication EH40.  Where there is no such data, then companies may assess this themselves.

Blanket wash: HDP Appro HMK1 WM  Blanket Wash

This comprises “Appro mixed alkanes and cylcoalkanes” (50-100%) which is not listed in EH40.  HDP have assessed the above as having a long-term workplace exposure limit of 150ppm.  HDP have not assessed the short-term limit, but the general rule of thumb is to regard this as being 3 x the long-term exposure limit where there is no data to suggest otherwise.

Varn VWM Wash

This comprises a “Blend of aromatic and aliphatic hydrocarbons and petroleum distillates”.  Again there is no listing in EH40 and Varn have not assessed a workplace exposure limit.  In my experience, comparible substances contain Naptha (petroleum) hydrotreated, light for which manufacturers have assigned a workplace exposure limit of 400ppm.

Isopropanol

The short-term exposure limit from EH40 for this is 500ppm and the long term exposure limit is 400ppm.  As this is permanently present, I have used the 400ppm figure as the workplace exposure limit.

Conclusions

The concentrations of substances present very close to their point of emission were:

With dispersion which would occur between the emission points and the positions in which personnel spend their time, the actual exposure would be further attenuated.  Therefore, there is no concern with the exposure to print personnel from the main substance present in the workplace.

Workplace atmosphere measurement 3: Blanket washing on small web-fed litho printing press

The concentrations measured using the Draeger tube were of the order of 10 parts per million (ppm).  Wash-up solvents are normally based on Naphtha (Petroleum) Hydrotreated. 


Substance

Test type

Reading
ppm

WEL
ppm

Blanket wash

 

Hydrocarbon Draeger tube

<10

350

Activated carbon tube with subsequent laboratory analysis

1.8

2.9

The results from the more accurate sampling carried out using activated carbon sampling tubes showed levels of 6.8 and 11.1 mg/m3 .  Naphtha (Petroleum) Hydrotreated is a complex mixture but if we assume that it has an equivalent molecular weight to that of toluene (92), then these figures translate into 1.8 and 2.9 ppm, ie lower than the Draeger tube readings but of the same order.  The conversion from mg/m3 to ppm is as stated in the HSE publication EH40/2005.

There is no workplace exposure limit for this in the EH40/2005 but chemical manufactures apply a long-term exposure limit of 300 to 400 ppm and no short-term limit.  Therefore, the indications are that the concentrations are well below a level which could be expected to cause health problems. 

Workplace atmosphere measurement 4: Methyl Ethyl Ketone (Butan-2-one) from inkjet printing.

This occurred on a small printer producing bar codes.  Extraction was provided at floor level (MEK is heavier than air).

Room volume 103 m3
Extraction Rate 0.557 m3/s via 6 vents
Air changes 19/hour
Concentration 100 ppm

The indications are that, even with very high extraction rates, general room extraction is insufficient to control the MEK concentration.  Therefore, extraction local to the ink jet heads is desirable.

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Chemical measurement data in printing workplaces