Biomedical subjects

Juha Laitinen

Publications and source records attributed to Juha Laitinen.

6 recordsLinked to original sources

PubMed2006

Task-based dermal exposure models for regulatory risk assessment.

The regulatory risk assessment of chemicals requires the estimation of occupational dermal exposure. Until recently, the models used were either based on limited data or were specific to a particular class of chemical or application. The EU project RISKOFDERM has gathered a considerable number of new measurements of dermal exposure together with detailed contextual information. This article describes the development of a set of generic task-based models capable of predicting potential dermal exposure to both solids and liquids in a wide range of situations. To facilitate modelling of the wide variety of dermal exposure situations six separate models were made for groupings of exposure scenarios called Dermal Exposure Operation units (DEO units). These task-based groupings cluster exposure scenarios with regard to the expected routes of dermal exposure and the expected influence of exposure determinants. Within these groupings linear mixed effect models were used to estimate the influence of various exposure determinants and to estimate components of variance. The models predict median potential dermal exposure rates for the hands and the rest of the body from the values of relevant exposure determinants. These rates are expressed as mg or microl product per minute. Using these median potential dermal exposure rates and an accompanying geometric standard deviation allows a range of exposure percentiles to be calculated.

Environmental Monitoring↗

PubMed2006

Default values for assessment of potential dermal exposure of the hands to industrial chemicals in the scope of regulatory risk assessments.

Dermal exposure needs to be addressed in regulatory risk assessment of chemicals. The models used so far are based on very limited data. The EU project RISKOFDERM has gathered a large number of new measurements on dermal exposure to industrial chemicals in various work situations, together with information on possible determinants of exposure. These data and information, together with some non-RISKOFDERM data were used to derive default values for potential dermal exposure of the hands for so-called 'TGD exposure scenarios'. TGD exposure scenarios have similar values for some very important determinant(s) of dermal exposure, such as amount of substance used. They form narrower bands within the so-called 'RISKOFDERM scenarios', which cluster exposure situations according to the same purpose of use of the products. The RISKOFDERM scenarios in turn are narrower bands within the so-called Dermal Exposure Operation units (DEO units) that were defined in the RISKOFDERM project to cluster situations with similar exposure processes and exposure routes. Default values for both reasonable worst case situations and typical situations were derived, both for single datasets and, where possible, for combined datasets that fit the same TGD exposure scenario. The following reasonable worst case potential hand exposures were derived from combined datasets: (i) loading and filling of large containers (or mixers) with large amounts (many litres) of liquids: 11,500 mg per scenario (14 mg cm(-2) per scenario with surface of the hands assumed to be 820 cm(2)); (ii) careful mixing of small quantities (tens of grams in <1l): 4.1 mg per scenario (0.005 mg cm(-2) per scenario); (iii) spreading of (viscous) liquids with a comb on a large surface area: 130 mg per scenario (0.16 mg cm(-2) per scenario); (iv) brushing and rolling of (relatively viscous) liquid products on surfaces: 6500 mg per scenario (8 mg cm(-2) per scenario) and (v) spraying large amounts of liquids (paints, cleaning products) on large areas: 12,000 mg per scenario (14 mg cm(-2) per scenario). These default values are considered useful for estimating exposure for similar substances in similar situations with low uncertainty. Several other default values based on single datasets can also be used, but lead to estimates with a higher uncertainty, due to their more limited basis. Sufficient analogy in all described parameters of the scenario, including duration, is needed to enable proper use of the default values. The default values lead to similar estimates as the RISKOFDERM dermal exposure model that was based on the same datasets, but uses very different parameters. Both approaches are preferred over older general models, such as EASE, that are not based on data from actual dermal exposure situations.

Environmental Monitoring↗

PubMed2005

Evaluation of exposure to 1-alkoxy-2-propanols and 1-(2-methoxy-1-methylethoxy)-2-propanol by the analysis of the parent compounds in urine.

Floor lacquerers' inhalation and total exposure to 1-alkoxy-2-propanols and 1-(2-methoxy-1-methylethoxy)-2-propanol (DPGME) were measured. The total exposure was biomonitored by urinalysis of free unchanged 1-alkoxy-2-propanols and DPGME. The floor lacquerers' 8-h inhalation exposures to 1-methoxy-2-propanol (PGME), 1-butoxy-2-propanol (PGBE) and DPGME were 1.9+/-1.3 (mean+/-S.D., n=15), 1.0+/-1.4ppm (n=11) and 0.2+/-0.3ppm (n=11), respectively. The gravity-corrected urinary excretions of PGME, PGBE and DPGME were 5.3+/-5.4mumol/l, 0.9+/-0.9mumol/l and 1.5+/-2.8mumol/l, respectively. A linear relationship was found between the gravity-corrected urinary excretion of PGME (R(2)=0.82), PGBE (R(2)=0.93) and DPGME (R(2)=0.93) and their preceding 8-h inhalation exposure. The correlations between the uncorrected urinary excretions and inhalation exposures to PGME, PGBE and DPGME was also calculated and found good (R(2)=0.82-0.95). The effect of work strain on the total exposure seemed to be more relevant in the exposure to hydrophilic PGME than in the exposure to more lipophilic PGBE.

Air Pollutants, Occupational↗

PubMed2005

Variety in dustiness and hygiene quality of peat bedding.

Respiratory exposure to organic dust induces chronic pulmonary diseases both in farmers and horses. The aim of this study was to examine the variation of dustiness and hygiene quality of peat moss bedding. Materials studied were weakly decomposed sphagnum peat (A), weakly decomposed sphagnum peat warmed up in storage (> 30 degrees C) (B) and two more decomposed few-flowered sedge peats (C and D). The geometric mean of mesophilic fungi, thermotolerant fungi and thermophilic actinomycetes were determined from the material. Samples of inhalable dust and endotoxins were collected with IOM samplers and respirable dust with 10M foam samplers when the peat was rotated in a cylinder. The number of particles was detected with an optical particle counter. An LAL assay was used for analysing endotoxins from the filter samples. There were differences in the hygiene quality and dustiness between peat materials (p < 0.01). The geometric mean of fungi was smallest in material A. Warming-up increased the number of fungi in sphagnum peat, but on the other hand, it decreased the content of endotoxin (p < 0.01). Few-flowered peat materials contained thermophilic actinomycetes and material D also contained Aspergillus fumigatus. The concentrations of inhalable dust, respirable dust and the number of particles were smaller in the few-flowered peats (C-D) than in the sphagnum peats (A-B). It is concluded that there are differences in the dustiness and hygiene quality of peat bedding.

Air Microbiology↗

PubMedDate not supplied

Laboratory and field testing of particle size-selective sampling methods for mineral dusts.

The performances of eight sampling devices were tested with mineral dusts in the laboratory and in a talc production plant. The IOM sampler was chosen as the reference method for inhalable dust, and the IOM samplers provided with the porous plastic foam media were used as the reference methods for both the thoracic and respirable aerosols. The other size-selective instruments tested included the Respicon virtual impactor, the optical GRIMM aerosol monitor, and a two-stage cascade impactor with cut points of 10 and 4 microm. The 37-mm cassettes were also included both as open- and closed-face versions. The study confirmed the usability of the IOM samplers for mineral dust, not only in its original version for the inhalable fraction but also its modified versions for the thoracic and respirable fractions. A high correlation with the two-stage impactor results is an indication of good reproducibility. The results increased the evidence that the 37-mm cassette is a poor indicator of inhalable aerosol. The concentrations obtained with both cassette methods were not only systematically too low but also showed large collection efficiency variability. Therefore, the results cannot be corrected by using correction factors. The concentrations of inhalable aerosol measured with the Respicon were generally low, but its performances for the thoracic and respirable fractions were closer to those for the reference samplers. The results also indicate that the GRIMM monitor is well-suited for such mineral dust determinations when very good accuracy is not required, but the immediate availability of the result is more important.

Air Pollutants, Occupational↗

PubMedDate not supplied

Control of workers' exposure to airborne endotoxins and formaldehyde during the use of metalworking fluids.

The study evaluated the effects of triazine use and machine enclosure on workers' exposure to bacteria, endotoxins, and formaldehyde in the use of metalworking fluids (MWF). Concentrations of triazine and bacterial contaminants were monitored in bulk samples of MWF from two machines in one workplace. One of the machines was used normally; triazine was added to the other when needed. Air sampling was used to estimate workers' exposure to endotoxins at 18 workplaces near enclosed and open machines. Concentrations of triazine in MWF and formaldehyde in the air were measured. Some recirculating local exhaust ventilation systems were also tested. The endotoxin and bacteria concentrations in the biocide test of MWF rapidly increased when the biocide levels decreased below 500 ppm. Airborne concentrations of endotoxins were substantially lower near enclosed machines than near open ones. Concentrations of airborne formaldehyde were below the Finnish occupational exposure limit at the existing levels of triazine in MWF. Concentrations of triazine in MWF correlated well with those of formaldehyde in the air near the machines (correlation coefficient r=.69). The results showed that the triazine levels in MWF should continuously be kept high enough (>500 ppm) to prevent workers' exposure to endotoxins and bacteria. Overdosing with triazine, however, should be avoided, so that the levels of airborne formaldehyde remain low. Triazine levels in MWF can be followed by the method described in this article. Workers' exposure to contaminants of MWF can be reduced substantially by enclosing the machines and equipping them with local exhausts.

Aerosols↗