Table 3.
Summary of TDI exposure studies for the main processes.
| Sector | Study populations (country, no. workers) | Biomonitoring data [expressed as range (median)] | Notable correlations/comments | LaKind scoringa | References |
|---|---|---|---|---|---|
| Continuous foam production | Poland (n = 20) | Sum-TDA (U) = <0.01–3.9 µmol mol−1 cr. | Positive for geometric mean (GM) in each group (r 0.9) U_totTDA (µmol mol−1) = 0.10777_TDI (µg m−3) + 0.2178 [5 ppb TDI = 4.1 µmol mol−1 cr.] RPE used and observed to impact TDA(U) results (no correlation between individual urinary TDA concentrations and TDI air concentrations). | 12 | Swierczynska-Machura et al. (2015) |
| UK (n = 26, 13 handlers, 13 non) | Sum-TDA (U) = <~0.4 to 7 (2.21) µmol mol−1 cr. (handlers) | No correlation between post-shift urinary TDA concentration and airborne TDI concentrations (r = 0.027). Dermal considered a significant factor—urine 20× higher for same airborne exposure. | 16 Methodology not well described | Austin (2007) | |
| Belgiumb (n = 9) | Sum-TDA (U) = 4.4–142.6 (18.01b) µg l−1 [21 samples] [~3 to ~97 (~12.3) µmol mol−1 cr.] | TDA (µg g−1) = 0.547_TDI (µg m−3)–1.636, r = 0.917 [5 ppb TDI =19.2 µg g−1, 17.8 µmol mol−1 cr.] Proposed measuring ‘increase over shift’ to exclude accumulation. | 12 External QA | Geens et al. (2012) | |
| Finland (n = 17) | Sum-TDA (U) = <0.05 to 39 µmol mol−1 cr. | Good correlation between airborne TDI and urinary TDA in post-shift samples (r = 0.91 and 0.86 for the two different factories studied). | 13 | Kääriä et al. (2001) | |
| Sweden (n = 6) | 2,4-TDA(U)/2,6-TDA(U) 0.5–5.4/0.2–4.7 µg l−1 [~0.3–3.7/0.14–3.2 µmol mol−1 cr.] 2,4-TDA(P)/2,6-TDA(P) 0.1–14/0.7–12 µg l−1 | Samples taken Monday morning so results not comparable to other studies. Only reported levels ‘above reference value’. | 12 Creatinine and specific gravity | Tinnerberg et al. (2014) | |
| Swedenc (n = 4 in 2000, n = 6 in 2005) | 2,4-TDA (U) ~ 0–10 µmol mol−1 cr. 2,6-TDA (U) ~ 0–35 µmol mol−1 cr. 2,4-TDA (P)/2,6_pTDA (µg l−1) In 2000: 2.9–27.2 (7.0)/8.2–62.1 (30.8) In 2005: 0.5–1.3 (1.0)/2–11.8 (4.0) | Urine results only presented graphically. | 14 Small study | Tinnerberg and Mattsson (2008) | |
| Finland (n = 17) | Sum-TDA(U) 0.2–39(4.9) µmol mol−1 cr. Sum-TDA(P) 0.4–70.8 (5.6) µg l−1 Sum_TDA(Hb) 0.012–0.33 (0.047) (nmol g−1) | Air TDI and plasma TDA correlated (r = 0.91). Plasma and urine TDA well correlated (r = 0.97). | 13 | Säkkinen et al. (2011) | |
| UK (n = 71) | Sum-TDA(U) <0.5–15.5 (1.3) µmol mol−1 cr. 2,6-TDA(U) <0.5–13.2 (0.8) µmol mol−1 cr. 2,4-TDA (U) <0.5–5.6 (0.7) µmol mol−1 cr. | The companies visited were involved in the manufacture of PUR products. | 11 | Cocker et al. (2009) | |
| UK (n = 90) | Sum-TDA(U) (µmol mol−1 cr.) <0.4–6.5 (90%, median <LOD) | Positive association observed in 4 pairs of samples (air and urine). Air levels <LoD at 2/5 sites and only 1/11 samples >WEL (20 µg m−3 NCO)— no further data. 446 samples analysed of which 280 were below the detection limit. Follow-up to Cocker et al. (2009). | 12 | Keen et al. (2012) | |
| Mixed | Sweden (n = 136) (including: moulding-, continuous foam-, and flame-lamination plants) | 2,6-TDA(U) <0.05–43.1 µg l−1 [~<0.03–29.3 µmol mol−1 cr.] 2,6-TDA(P) <0.05–62.1 µg l−1 | Correlation (r > 0.86) with air levels for both urine and plasma for same-day samples. Same sites as Sennbro et al. (2004). | 12 | Littorin et al. (2007) |
| Sweden (n = 81) | 2,4-TDA(U)/2,6-TDA(U)/Sum-TDA(U) <0.1–47 (4.5)/<0.1–115 (3.7)/<0.1–162 (9.7) µg l−1 [~<0.07–32 (3.1)/ −78 (2.5)/−110 (6.6) µmol mol−1 cr.] 2,4-TDA(P)/2,6-TDA(P)/Sum-TDA(P) <0.1–31 (7.4)/<0.1–42 (6.1)/<0.1–70 (14) µg l−1 | High correlations between air exposure and urinary biomarker levels (ranging from 0.75 to 0.88) or plasma biomarker levels (ranging from 0.50 to 0.78). 2,6-TDA(U) (µg l−1) = 2.7_TDI(ppb) + 0.02 (r = 0.88) [5 ppb = 97 µg l−1, ~66 µmol mol−1 cr.] | 13 | Sennbro et al. (2004) | |
| Japanb (n = 18) (spraying urethane paints) | Individual results not reported except graphically, 2,6-TDA(U) <19 µmol mol−1 cr. | 2,6-TDA(U) (µg g−1) = 6.6_TDI (ppb) –1.43 (r = 0.91) [5 ppb = 29 µmol mol−1 cr.] | 13 Both raw and corrected data | Sakai et al. (2005) | |
| Finlandb (n = 6, car repair; n = 15 other PUR processes) | Car repair Sum-TDA(U) <0.02–0.76 (0.23) µmol mol−1 cr. Other processes <0.02–0.17 (0.07) µmol mol−1 cr. | Other processes included milling and turning of PUR-coated metal cylinders, injection moulding of thermoplastic PUR, welding of district heating pipes and joint welding of PUR floor covering. | 11 | Rosenberg et al. (2002) |
aThe lower the LaKind score the better the overall quality (possible range 8–24).
bGeometric mean rather than median.
cCountry of origin assumed from authors’ affiliation, not specifically stated in paper.