Recent research has found that consumers in Delhi are purchasing vegetables with high levels of heavy metals (HMs). The vegetables were studied for their presence of lead, zinc and cadmium include palak (spinach), gobhi (cauliflower) and bhindi (okra). The findings are the outcome of a research project funded by the United Kingdom Department for International Development (DFID). Heavy metals are one of a range of important types of contaminants that can be found on the surface and in the tissue of fresh vegetables. Legally permissible limits as defined by the Indian Prevention of Food Adulteration Act (PFA), 1954 are regularly crossed, whilst these norms are less strict than international food safety norms like Codex Alimentarius or European Union standards. There is no regular testing of heavy metals in vegetables by the designated authorities in India.
The main cause for concern in terms of contamination of vegetables in Delhi by heavy metals relates to Lead (Pb). 72 % of 222 (quality controlled) samples of palak contained Lead concentrations that exceeded the PFA's permissible limit of 2.5 mg/kg. If the more stringent CODEX limit of 0.3 mg/kg is used, then 100% of the palak samples exceeded safe limits. Another cause of concern is Zinc levels. 21 % of 609 palak samples analysed showed Zinc concentrations that exceeded Indian PFA limits (50 mg/kg). 3% had concentrations at twice the PFA limit. In this case there are no International standards that are more stringent than the Indian standards.
Chemical contamination from sources such as industries, vehicles and pesticides can affect the safety of food. Prolonged human consumption of unsafe concentrations of heavy metals in food stuffs may lead to the disruption of numerous biological and biochemical processes in the human body. Heavy metal accumulation gives rise to toxic concentrations in the body, while some elements (e.g. arsenic, cadmium, chromium) act as carcinogens and others (e.g. mercury and lead) are associated with developmental abnormalities in children.
Heavy metals may be present as a deposit of the surface of the vegetable, or may be taken up by the crop roots and incorporated into theplant tissue. In either case the original source of the pollution may be from water borne sources (such as industrial effluent) or from industrial or vehicular air pollution. This distinction is very important, because metal deposited on the surface of the crop can often be washed off by consumers prior to consumption.Vegetable crops are often grown in polluted and degraded environmental conditions in the peri-urban (or urban fringe) zone and are subject to further pollution from vehicles and industries during marketing. There is therefore significant cause for concern regarding contamination.
The research has also provided clear evidence of the fact that vegetable production also has a major role to play in supporting the livelihoods of the poor. Vegetable farming in Delhi is mainly conducted by farmers with low socio-economic status cultivating small or marginal landholdings. These people often have little choice but to farm in polluted areas, and have limited access to advice and support. Small holder farmers have a preference for growing palak and all family members, that is women, children and men contribute. In addition, the poorest groups of agricultural wage labourers work on vegetable farms.
Urban food security in India is a matter of growing concern. It is estimated that by 2025, 60% of Indias population will be living in urban areas, and an increasing proportion of city dwellers are poor. Urban poverty is reflected in the nutritional status of the urban poor, whose intake of important nutrients frequently lies below the minimum recommended daily allowance. In this context it is particularly important to encourage the consumption of highly nutritious fruit and vegetable (F&V) crops. However, since the income elasticity of demand for these products tends to be high, there is a clear need to increase supply and maximise the nutritional quality of these products to benefit the poor.
This is also acknowledged by the Government of Indias policy, which recognizes the long term preventative need for sustained increased consumption of fresh vegetables and fruits, rather than distribution of iron and vitamin supplements. Research from the study has also shown that awareness is slowly increasing about the nutritional benefits of consuming vegetables, and of Palak in particular.
Everyone affected, poor more than rich
Poor urban consumers (defined as those households with monthly incomes of less than 3000 rupees) could be affected more by the heavy metals present in vegetables purchased. Several reasons may be attributed to this including: Poor consumers wash their vegetables less thoroughly than better off consumers; the poor may purchase vegetables that have been in the market for a longer time at a lower price, therewith increasing the risk of longer exposure times of the vegetable to aerial deposition of heavy metals; the poor have less access to higher priced food that is perceived to be of higher quality and the poor may be more susceptible to the adverse effects of HMs due to an already unfavourable relative health and nutritional situation, with particular reference to women and children. Also, the research teams consumer studies indicate that awareness of food safety issues is lower amongst lower income groups.
On the other hand, wealthy consumers may be more exposed to HMs through greater overall consumption of vegetables. The wealthy are able to purchase costly off season vegetables when high doses of agro-chemicals (some containing heavy metals) are applied by farmers to stave off insect pests.
Reducing crop contamination, safer vegetables
Several interventions have potential to improve food safety. These interventions can be made with the producers, at the linkages between market infrastructure and market coordination and also on public awareness of food safety hazards.
Awareness of safety hazards through information targeted at consumers as well as market intermediaries is needed. Experimental programmes by the research team have highlighted that a simple, low cost opportunity for people to reduce HM contamination is by thorough washing of vegetables in clean water. The study found that at least 50% of the Lead contamination on palak is found on the surface of the vegetables and by twice washing in clean water the Pb contamination can be reduced to within PFA safe limits. But, clearly the potential to reduce HM contamination by thorough washing depends on the access that people have to clean water sources, and competing needs for this scarce commodity. Ironically, this may be a barrier for some of the poorest communities who also face the greatest risks. Improved water supply and sanitation, which is already recognised as an important poverty alleviation tool, can contribute to reducing food contamination.
Ensuring safe food needs the highest priority and an integrated policy. Current policy relates to food standards, environmental standards, industrial siting, peri-urban agriculture and consumer rights separately and is inadequate to tackle the issue comprehensively. Clearly food contamination can take place at various stages of the food chain, and food safety needs to be ensured throughout for it to be safe for consumption. Starting from the cleaner production sites, to transport and marketing practices (both wholesale as well retail) and consumer practices, various interventions need to be made. Policy approaches to food safety need to based on prevention rather than command and control of food quality at the retail end of the food chain. Such an approach will also reduce the need and the cost for expensive inspection regimes, which are particularly difficult to implement with regard to fragmented small-scale food economies, like vegetable retailing.
An integrated approach can be incorporated through an empowered multi-stakeholder agency such as a food safety board, for example which has powers to examine the issue in all its aspects. Such approaches have also worked in other countries and have previously been proposed in India by Indian advisory committees. For instance, the 1998 Task Force to the Prime Ministers Office under Nusli Wadia recommended setting up an integrated Food Regulatory Authority to deal with all food safety issues, but currently no such body exists.
