‘The brighter the worse’: Lead content of commercially available solvent-based paints intended for residential use in Pakistan

Introduction

Exposure to lead (Pb) among children through Pb-based house paints has been a global concern over the last 50 years. Despite regulatory and safety measures for paint manufacturers and bans on the use of Pb in house paints, Pb-based house paints are still produced and used globally, largely in low- and middle-income countries (LMICs) (Clark et al., 2006; Ewers et al., 2011; Kumar & Gottesfeld, 2008; Lin et al., 2009; Megertu & Bayissa, 2020; Montgomery & Mathee, 2005; Njati & Maguta, 2019; O'Connor et al., 2018). Paints constitute a significant source of environmental Pb pollution, particularly of the home environment (Adebamowo et al., 2007; Clark et al., 2006; Ewers et al., 2011; Kumar & Gottesfeld, 2008; Lin et al., 2009; Njati & Maguta, 2019; O'Connor et al., 2018).

Pb exposure can cause various health problems, ranging from anemia and hypertension to impaired function of the immune, reproductive, and nervous systems. Children who are exposed to Pb exhibit a dose-dependent reduction in brain volume, as well as deficits in school performance and measures of intelligence (Cecil et al., 2008; Chandramouli et al., 2009; Evens et al., 2015; Lanphear et al., 2005). These deficits persist into adulthood (Mazumdar et al., 2011; Shih et al., 2006). Globally, 800 million children are estimated to have elevated blood lead levels (BLLs >5 μg/dL) (UNICEF & Pure Earth, 2020). 5 μg/dL is a commonly used reference level, although lower BLLs are still considered dangerous (CDC, 2022).

A recent systematic review found that Pakistan had the second-highest mean childhood BLLs among LMICs (9.27 μg/dL) and estimated that 46.7 million children in Pakistan have BLLs >5 μg/dL (Ericson et al., 2021). Economic losses due to Pb exposure in Pakistan alone are estimated to be $38 billion, equivalent to 7.8% of GDP (Attina & Trasande, 2013). In Pakistan, multiple sources of Pb exposure have been recognized, including food, house dust, respirable dust, and to a lesser extent surma and petrol (Fatmi et al., 2017). Although paint is an important contributor to Pb in house dust, and associations have been found between raised childhood BLLs and Pb paint in homes, very little research relating to paint Pb levels in Pakistan has been published (Khan et al., 2001).

This study therefore investigated the Pb content of solvent-based residential use paints commercially available in Pakistan. A previous study identified that the majority of solvent-based paints in Pakistan had high Pb levels (Khalid et al., 2017). Since then, the Pakistan Standards and Quality Control Authority introduced a mandatory standard limiting the Pb content of paint to 100 ppm (WHO, 2022). The opportunity to assess the effectiveness of the new standard further motivated this review of Pb levels in paints available on the market. The study findings may help policymakers and regulators enforce Pakistan’s Pb paint standards.

Methods

Results

Table 1 summarizes the Pb concentrations of all paint sampled in the current study and groups them by color. For the 60 samples collected, the mean Pb concentration was 8,158 ppm. We found a maximum Pb concentration of 97,000 ppm, which is almost 1,000 times the standard limit.

Yellow paints had the highest Pb content among all the brands sampled for the study. Approximately 76.2% (n=21) of the yellow paints had Pb concentrations of >100 ppm. The mean concentration of yellow color paints was 23,021 ppm and the maximum value was 97,000 ppm. Approximately 36.8% of the samples of red paints (n=19) had Pb levels of >100 ppm. The color with the lowest Pb content was white, with only one sample containing Pb levels of >100 ppm.

Only one of the paint samples from multinational brands had Pb levels of >100 ppm. Multinational brands had lower mean (1,228 ppm) Pb levels than both national and local brands. National brands had mean and median Pb levels of 5,354 ppm and <60 ppm respectively, with 34.8% (n=8) of paints containing Pb. The highest concentration of lead was found in brands local to Karachi, with more than 68% (n=15) containing levels exceeding 100 ppm and a mean Pb level of 15,807 ppm (Table 2).

Table 3 pertains to labeling on paint cans and whether adequate safety information was displayed. Of the 60 paint samples, 42 had no labeling mentioning Pb and of those almost half (46.2%) had Pb levels of >100 ppm. By contrast, of the 18 samples labeled Pb-free, four had Pb levels of >100 ppm, with a mean of 2,407 ppm and a maximum value of 18,000 ppm.

Table 3 further classifies paints based on product standards manufacturers claimed to have followed, per can labeling. Relevant product standards included Pakistan standards and international standards. Twenty-three samples were labeled with international standards, including ISO, IAS, OHSAS, and Malaysian standards. Of these more than one-third (n=8) had Pb levels of >100 ppm, with a mean of 4,444 ppm and a maximum of 48,000 ppm. Nine samples were labeled Pb-free and with either international or Pakistan standards; of these, two had Pb levels of >100 ppm, with a mean Pb level of 2,112 ppm and a maximum of 17,000 ppm.

Fifteen paints sampled appeared with the same brand and color combination in Khalid et al.’s (2017) study. Three brands had two colors appear in both studies, and another three brands had three colors appear in each study. All of the six brands that appeared in both studies were multinational or national brands. Of the fifteen paints that appeared in both studies, nine had a lower Pb content than in 2017, one had a higher Pb content, and five remained the same. All of the brands present in both studies had reduced their maximum Pb content since 2017. The greatest decrease was from 110,000 ppm in 2017 to 18,000 ppm in 2021. Of the six brands present in both studies, four still had Pb content in 2021 that was above the national standard. Only two brands had brought their Pb levels into line with standards.

Discussion

Pakistan has lagged behind in implementing its Pb paint regulations. Its first paint regulations were issued in 2017, allowing only paints with Pb levels of <100 ppm (WHO, 2022). Further effort is required to fully implement those regulations. 40% of the paints sampled in this study had Pb levels higher than the legal limit. Almost one-fifth (18.3%) of the paints had Pb levels of >10,000 ppm, and the highest Pb concentration detected was 97,000, almost 1,000 times the legal limit. Pakistan’s mean paint Pb concentration of approximately 8,000 ppm is within the range observed in other Asian countries (O'Connor et al., 2018).

Comparing our results to those published in 2017, we note a decrease in paint Pb content. While 40% of the paint samples collected in our study were above the allowable limits, in the previous study 60% failed to comply with the standards (Khalid et al., 2017). There is, however, some uncertainty in interpreting comparisons between the two studies, as the sampling took place in different cities and the range of paints sampled was not identical.

The current study finds that yellow paints contain the highest Pb levels. More than three-quarters (76.2%) of the yellow paints sampled had Pb levels of >100 ppm. By contrast, only 36.8% of red paints and 5% of white paints exhibited high Pb levels. These findings are consistent with previous studies (Clark et al., 2009, 2015). The most common Pb additives in paints are yellow and red pigments (lead chromates), driers (lead octoate and lead naphthenate), and anticorrosives (lead tetroxide) (UNEP, 2022). Lead carbonate is used in white paints, but has now been largely replaced by titanium dioxide. Given that the average Pb content of colored paints is higher, paint manufacturers likely intentionally add Pb to augment color (O'Connor et al., 2018). Notably, even the yellow paint produced by a multinational brand with a high market share had 18,000 ppm, exceeding national limits.

The current study finds that labeling of cans is not accurate or universally practiced. 22% of paints labeled Pb-free contained Pb levels above 100 ppm, up to a maximum of 18,000 ppm. Such false labeling has been identified elsewhere, especially in countries where there is no regulatory control. A study of paints in South and Southeast Asia revealed that almost 18% of paints labeled Pb-free contained high Pb levels of up to almost 56,000 ppm, undermining the reliability of such labeling (Weinberg & Clark, 2012). Within Pakistan, the 2017 study showed a similar result, where 43% of paints labeled Pb-free contained high Pb levels (Khalid et al., 2017).

Pakistan currently has a vast, largely unregulated paint market, wherein, according to industry reports, the unorganized sector accounts for an estimated 34% of production and numerous cheaper brands come under its umbrella (Khalid et al., 2017). In a study conducted in India, the unorganized sector comprised small businesses, while all large firms and multinationals fell under the category of organized (Mohanty et al., 2013). Applying a similar lens to the current study, and considering all local Karachi brands to fall under the category of unorganized, we find that not a single brand from this sector follows the standards. The two highest Pb levels detected, 97,000 ppm and 70,000 ppm, were found in these brands. This is reflected in the India study as well, where 93% of paints sampled within the unorganized sector had Pb of >300 ppm. It is likely that cost-cutting practices and a lack of regulatory adherence by the unorganized sector poses a major barrier to the curbing of Pb in paint.

Limitations of the current study include that it was conducted solely in Karachi, and only investigated residential-use solvent-based paint, so it may not provide a representative picture of paints in Pakistan. Further research into the impact of current paint lead levels on national health, through blood lead level testing, would also be of benefit.

The technology to produce Pb-free paint is being put to use in Pakistan, but there remains ample room for improvement. A substantial proportion of paint being sold continues to put lives and health at risk.

Author contributions

Conceptualization, Z.F. and L.C.; methodology, D.S., Z.F., and L.C.; software, D.S.; validation, D.S., Z.F. and L.C.; formal analysis, D.S.; investigation, L.C., and D.S.; resources, L.C., and Z.F.; data curation, D.S.; writing – original draft preparation, D.S.; writing – review and editing, Z.F., L.C. and C.L.; visualization, D.S.; supervision, Z.F.; project administration, D.S. All authors have read and agreed to the published version of the manuscript.

Ethical considerations

Institutional Review Board Statement: The Aga Khan University Ethics Review Committee (Karachi, Pakistan) approved this study under its ‘Exemption’ category (#2022-7187-20616).