The contamination of hospitals and pharmacies by ADs and related occupational exposures and risks have been studied before and indicated potential health hazards during life-long exposures [25, 16]. Much less attention has been paid so far to potential contamination in the households of patients treated with AD chemotherapies despite the increasing trends in using take-home anti-cancer therapies [30]. The present research aids in this underestimated problem where the studies of AD indoor contamination outside of hospitals or pharmacies are very rare. To our knowledge, there are only 3 reports. Two papers documented a study from Japan that considered 3 homes of patients treated with AD chemotherapy and reported CP residua on toilet or bathroom surfaces ranging 30–7340 pg/cm2 [39, 40]. The second study from Germany investigated homes of 13 patients and reported contamination by Pt ranging 0.02–42.5 pg/cm2 and CP up to 283.3 pg/cm2 [5]. This latter study showed CP residues mostly on toilet surfaces and also in the urine of family members [5].
In the present paper, we focused on both the traditionally studied floors that are a major issue in healthcare facilities [24], but also on other surfaces in patient households that might be contaminated, e.g., by the patient sweat such as the tables, chairs or other desktops. Our samples were collected during the summertime (May–September period in Europe) when the contact with sweaty skin is the most intensive providing thus the indication of the highest possible exposure situations.
In agreement with previous studies, CP and Pt were the most important exposures markers [1] and were detected in high frequencies during the chemotherapy of patients as capture in the first sampling (66.6% positive for CP and 63% positive for Pt). Besides, PX was also rarely detected with 8% of samples positive. Correspondingly to studies of Yuki et al. [39], and Böhlandt et al. [5], floors in toilets and bathrooms were often contaminated due to possible spills of patient excretion (maxima CP 235.7 pg/cm2, Pt 2.7 pg/cm2 and PX 3.8 pg/cm2). However, we further observed high frequency (67.1% positive) of CP contamination also on desktops in kitchens and living rooms with actually the highest detected CP concentration in the present study 511.7 pg/cm2.
The floor contamination by ADs observed in the households has been much lower in comparison with available pharmacy and hospital studies where accidental values higher than 100 ng/cm2 (for CP) or higher than 10 ng/cm2 (Pt) were reported [20, 33, 37]. Our recent study concerned 26 hospitals in the Czech Republic and showed median contamination of hospital toilet floors being 30, 200, 10 pg/cm2 for CP (N = 25), Pt (N = 18) and PX (N = 25), respectively [4]. Interestingly, the median values observed in the present study for CP (16.6 pg/cm2 for floors) were closely comparable, and the immediate exposures thus are similar in both occupational and household settings. Indeed, the safe long-term occupational limit of 100 pg/cm2 derived for CP in hospitals [10, 18, 35]. was exceeded in two households with the highest CP contamination, i.e., at participant No. 12 (511.7 pg/cm2 on the surface of a chair in the living room) and participant No. 3 living together with a child (235.7 pg/cm2 on the bathroom floor). It should, however, be noted that the occupational exposures last much longer compared to rather episodical situations when family members are potentially exposed to ADs during chemotherapy of the patients. This was also confirmed during the second control sampling in the present study (6 or more months post-treatment) when CP was below LOQ in 6 out of 11 households that were found CP-positive during the first sampling.
Our study further showed significantly elevated contaminations of homes by CP especially during the first six days after the chemotherapy. This is in agreement with the previous study that showed the release of unmetabolized AD during five days post-treatment [40]. Also, [16] highlights that precautions should be taken for manipulation with body fluids of patients during 7 days post-treatment.
Further, frequent and long-residing contaminations by CP were detected on the desktop surfaces during both the first and the second control samplings. Indeed, 3 out of the 4 CP-positive samples collected in the 2nd control sampling were from wooden surfaces of dining tables treated with a surface protecting wax or varnish layers (Additional file 1: Figure S1). This highlights that the patient sweat is an important source of secondary contamination and that the wax/varnish-treated surfaces that are often in direct contact with the patient may serve as long-term deposits of AD contamination. This observation is supported by our recent observations of CP mobilization from the wax-treated Marmoleum floors [4] as well as by other studies [16]. Possible accumulation of ADs on surfaces may also be explained by the recently reported negative correlation between the contamination and historical use of ADs, i.e., the age of pharmacies [21]. On the contrary, inert materials such as tiles used in bathrooms or toilets can easily be washed out keeping thus contamination under the control. It should also be mentioned that the patient questionnaire survey did not indicate any correlations between the levels of contamination and cleaning practices in individual households (see also Additional file 1: Table S2).
Besides CP, Pt-contamination was observed in patient households (63% samples positive during the first sampling), but with a low median of 0.2 pg/cm2 comparable to the available German household study [5]. The observed concentrations are two orders of magnitude lower than Pt-contamination in hospitals including the Czech Republic, where long-term monitoring data indicate a median of 200 pg/cm2 [4]. Here it should be critically noted that the analyses of total Pt, which is a common approach in the ADs monitoring studies [5, 19, 33, 38] do not allow to discriminate other different sources of Pt such as occupation (e.g., metallurgy), dental materials or breast implants [34]. Surface Pt concentrations below 0.1 pg/cm2 are considered as environmental background while higher levels indicate contamination [5]. Although our study does not allow us to draw strong conclusions on potential risks associated with Pt in households, low concentrations—namely in the second control sampling when Pt was below LOQ in almost all samples—suggest that possible risks of Pt (and also PX) are much lower compared to CP.
To our knowledge, this one of the first studies that investigated eventual AD contamination in hospices and retirement homes. During our pilot monitoring of hospices, no patients actively receiving chemotherapy were hosted in the studied facilities. Nevertheless, screening for 12 ADs in hospices showed elevated concentrations of Pt reaching up to 15.9 pg/cm2, which is considerable value even in comparison to the situation in some hospitals [20]. In one of the hospices, this contamination was traced back to a former oncology patient with diagnosed colorectal cancer that was previously treated with oxali-Pt containing chemotherapy. In this context, studies showed that Pt might accumulate in a body during the lifetime through, for example, covalent binding to sulfhydryl protein groups [41]. Correspondingly, levels of Pt up to 1000-times higher compared to the control population were observed in patients 20 years post-Pt-chemotherapy [8]. However, there is still a lack of detailed information on the pharmacokinetics of Pt-based drugs as recently highlighted by a large difference in the accumulation of cis-Pt and oxali-Pt in the patients [41].
In the monitored retirement homes, low contamination was expected as the available information about eventual AD-treated patients was poor. The management of the retirement homes estimated that they usually host a maximum up to 3 oncology patients per year, more information about clients eventually treated with chemotherapy was not available. Nevertheless, IF was detected in two of the floor samples (low level with max 3.3 pg/cm2) from the apartment that was formerly used by a resident with myeloma that passed away in 2018, i.e., 2 years before actual monitoring in 2020. Also, MET (3.3 pg/cm2) was detected in the apartment (floor sample) of the resident undergoing active oncology treatment with orally administered methotrexate. To our knowledge, the information on ADs in retirement or nursing homes is extremely rare. Only one study of nursing homes in the Netherlands reported that their clients received chemotherapy, mostly in outpatient clinics [24]. This study assessed dermal exposures of the staff to ADs (through resident washing or the in-house cleaning processes) and concluded on the low frequency of exposure and consequently lower risks for nursing home staff compared to, e.g., personnel in hospitals [24].
Although we are aware of the limitations of our pilot study, there are several lines of evidence indicating that Pt may reside in the body of patients for a long time, and it may be released during later life stages, thus posing hazards to family members or staff in retirement houses or hospices. Also, detection of IF on the floor of the retirement house 2 years after the latest potentially confirmed source might raise a concern of long-term accumulation (and release) of ADs from indoor materials [4]. Further research studies in these directions as well as research of newly introduced per orally administrated ADs might clarify the hypotheses.
Our findings indicate that the households of oncology patients may be contaminated by ADs. However, the information about potential AD hazards provided by the clinicians to patients was not sufficient, and the availability of preventive measures in the studied households was limited (see the questionnaire survey in Additional file 1: Table S2). For example, only 4 out of 17 participants had more than one toilet in the house, and a separate usage of a dedicated toilet by an oncology patient was thus generally limited. On the other hand, 10 participants lived together with susceptible individuals like small children. Consequently, we prepared written safety guidelines that specifically target patients and their family members that include practical and understandable recommendations on prevention, cleaning, handling of potentially contaminated materials such as laundry, etc. This flyer was inspired by other materials from Australia and Canada (e.g., https://www.health.qld.gov.au; http://www.bccancer.bc.ca), and it is systematically distributed to patients of the participating hospital, Masaryk Memorial Cancer Institute in Brno, as well as to other hospitals in the Czech Republic (the flyer in Czech is available at https://www.cytostatika.cz/index.php?pg=pro-pacienty). Briefly, the leaflet contains basic information about the ADs properties, proper handling and disposal (including handling and disposal of potentially contaminated body fluids or materials), as well as specific information for patients and family members about sexual life, pregnancy, and breastfeeding. The content and format of the flyer were also commented on by the patients enrolled in the present study, and the perception of the flyer was largely positive.