Survey of Chemical Substances in Consumer Products, No. 63 2005 – Mapping and release of chemical substances from products made of chloroprene

Mapping and release of chemical substances from products made of chloroprene

Summary

Health assessment

On behalf of the National Agency of Environmental Protection, the Danish Technological Institute has mapped the consumption and the consumption pattern of products made of chloroprene with which consumers get into contact.

The investigation showed initially that the shops or other sales channels do not know the word chloroprene, but solely the word neoprene, which is the raw material company of DuPont Dow Elastomers' trademark for chloroprene rubber.

The investigation has shown that a considerable amount of consumers gets into contact with products made from chloroprene. First of all products like support bandages, boots and waders contribute. Also the number of consumers who use wet-, semi wet -and dry suits for sport or exercise in the wet element is considerable.

It has been difficult to get precise numbers for the consumption of chloroprene products because many consumers only practise sport at individual basis as exercise. It is judged that the amount of consumers who during a year is in contact with support bandages and boots is around 100.000. With regard to waders the number is judged to be 50.000 and for isolating suits around 25.000. The number of comsumers using gloves is estimated to 40.000, but the number is uncertain as gloves are used for different sports and leisure activities. Professionals, e.g. windows polishing people, also use gloves.

Eight different types/brands of products made of chloroprene were selected for a screening analysis to detect any chemical substances contained in the products. The selection was based on the recognised consumer pattern and by taking contact times and the exposed skin area in consideration.

The products selected comprised two types of supports, two different brands of dive gloves, a pair of dive socks, a dive hood, a pair of waders and a dive suit.

The screening analyses included an element analysis using wavelength dispersive x-ray spectroscopy, gas chromatography with mass spectroscopic detection (GC/MS) of headspace, gas chromatography with mass spectroscopic detection of extracts of the products, and thin layer chromatography also of extracts of the products.

Raw chloroprene rubber contains approx. 30 – 40 weight percentage chlorine, depending on type. For a current sample received from a Danish rubber factory the content was measured at 34% w/w.

An amount of 30 – 50 weight parts of raw rubber will typically be used in a chloroprene recipe.

It is, therefore, remarkable that two of the eight products purchased, i.e. the two dive glove brands, appeared to contain chlorine only at trace level which was demonstrated by the x-ray analysis. Two other products, waders and dive socks, contained slightly less than 2% chlorine by weight basis indicating that the chloroprene content in these two products is quite low.

The dealers of the two products, which do not contain chloroprene, could not explain why this was so. However, both of them informed us that almost all of the rubber fabrics for neoprene products (chloroprene) are produced in the Far East and that it is impossible to receive precise information about the composition of the rubber fabrics from there.

The gas chromatographic/mass spectroscopic screening through headspace and analysis of extracts of the products themselves demonstrated the presence of a fairly large number of different types of substances. The concentrations in the headspace analysis appeared to be quite low, even at 100°C. The level is typical from 0.1µg/g – 3µg/g. For waders, however, the toluene level appeared to be 21µg/g.

Thin layer chromatographic screening was used to identify which types of anti-aging agents had been added to the products.

At the same time, it appeared to be suited to demonstrate whether ETU (ethylene-thio-urea as accelerator) had been used or not. This information was needed partly due to the fact that this substance appears in all the standard recipes published in The Rubber Formulary (Peter A. Ciullo), and partly due to the fact that the substance appears on the list of harmful substances under T (toxic), R61(may cause harm to the unborn child) and R22 (harmful if swallowed). In HSDB (Hazardous Substances Data Base), EPA (Environmental Protection Agency) has assessed the substance in terms of carcinogenic properties and it is classified as a group "B" substance and may therefore be carcinogenic to humans.

The thin layer chromatographic screening for anti-aging agents was consistent with the GC/MS analysis of the extracts of the products. On the other hand, the extracts was not found to contain ETU. This may be because ETU has not been used or has been transformed into the corresponding urea derivative when sulphur is released (Röthenmeyer).

Five products were selected for the migration tests based on the results of the initial screening analyses. A knee bandage, a pair of dive gloves, a dive hood, a pair of waders and a dive suit were selected.

The laboratory scale migration tests were based on "worst case" scenarios, with exposure times, contact media (artificial sweat and artificial sea water) and temperatures being as close to "real life" as possible.

In addition to a laboratory scale migration test, the dive suit was also subjected to a realistic full-scale sea test, which involved an experienced sport diver. The suit was a semi-wet suit and after two dives and a break on shore, the water was drawn off the suit.

The water was analysed by GC/MS for organic substances and by atom absorption using a graphite oven for nickel according to DS 2211.

It was quite interesting that migration of N,N’- diethyl-thio-urea occurred in this final test as opposed to the laboratory test that involved contact with artificial sea water. Since it has been verified that the dive suit contains N,N`-diethyl urea, it has to be concluded that the full-scale test was justified and that it is difficult to simulate real life in laboratory test alone.

The samples that contained from 7-14 %w/w chlorine all contained nickel in weight percentage concentrations ranging between 0.01 %w/w and 0.06 %w/w.

At first, it was assumed that the presence of nickel could have been caused by wearing particles in the rubber mixing department but towards the end of the project, the Danish Technological Institute realised that the nickel salt from dimethyl dithio carbamic acid or dibutyl dithio carbamic acid could be included in rubber recipes as a very efficient antiozonant in order to prevent oxidative breakdown of the rubber (R. Kuschel). The nickel release was therefore measured in the full-scale test with diving using a semi-wet suit. The test demonstrated that nickel was released in a 0.2µg/kg concentration.

Health assessment

The chemical substances released in measurable concentrations in the migration tests and identified unambiguously by the chemical analysis were judged in details for possible consumer health impacts.

The investigation of the selected chloroprene products revealed the release of a row of chemical substances.

In total 46 chemical substances were identified and assessed for health effects in the screening phase.

In the migration studies 7 “problematic” chemical substances were identified from the screening list for health effects. These chemical substances were selected for a closer assessment.

The table below contains a summary of this assessment.

Name	CAS no.	Values measured ^[1]	NOAEL ^[2]	Assessment
Isophorone	78-59-1	3 µg/kg and 0.1µg/kg	150 mg/kg	The values measured were significantly below NOAEL and the substance is not assumed to cause skin irritation. The substance is suspected of being carcinogenic.
Toluene	108-88-3	0.4µg/kg	625 mg/kg	The substance is not assumed to give rise to health impacts in the amounts measured.
Phenol	108-95-2	0.7µg/kg	LOAEL = 1.8 mg/kg	The substance is not assumed to give rise to health impacts in the amounts measured.
N,N-Dibutyl formamide	761-65-9	1.3µg/kg	60 mg/kg	The amounts found are not assumed to give rise to health impacts, however, the risk whether it can cause harm to unborn babies or not has not been clarified.
N,N-diethyl-thio-urea	105-55-5	6.7µg/kg	LD₅₀ = 300 mg/kg	The substance is probably not toxic in the amounts found, however, there is a risk that it may cause allergic contact eczema.
N-Butyl benzene sulfonamide	3622-84-2	2.4µg/kg	< 57 mg/kg	N-butyl benzene sulfonamide will probably not harm health in the amounts found but it should be pointed out that the data basis is very incomplete. There are indications that the substance can cause harm to reproduction.
Nickel (in ion form)	Cannot be indicated	0.2µg/kg	30.5 mg/kg	Based on the NOAEL specified, the amount of nickel measured here will not give rise to anxiety. However, the risk of allergy, cancer and harm to unborn babies should be noted.

The following appears from the table:

The amounts measured are far below the limits which it has been possible to find for zero impact levels for all the seven substances assessed.
None of the substances assessed cause skin irritation in the current concentrations.
The properties of some of the substances involve risks of chronic effects. As the substances all are present in very small amonts it is judged that the risk is very low.

Based on the products studied, it can be established that none of the substances found will directly give rise to health problems.

Footnotes

[1] The listed analysed amounts in the table are the amuounts which has a potential uptake per kg body weight by a 100 % dermal uptake.

[2] NOAEL (No Observed Adverse Effect Level).